Changes

Working version
--------------

(Changes that can break existing programs are marked with a "*")

### Language features:

### Runtime system:

- #14486, #14530: Add FreeBSD frame pointers support for AMD64 and ARM64.
  Document the usage of pmcstat and dtrace for generating profiling
  information.
  (Tim McGilchrist, review by Gabriel Scherer)

- #14494: Consistently use macro to test header promotion.
  (Nick Barnes, review by Gabriel Scherer)

- #14493: Use Scannable_* macros instead of comparisons to No_scan_tag, for
  legibility and correctness (fixes one bug, in weak.c).
  (Nick Barnes, review by Gabriel Scherer)

* #14559: Remove `caml_fatal_error_arg` and `caml_fatal_error_arg2`
  symbols from the runtime. The declarations were removed in 5.0.
  (Antonin Décimo, review by Nicolás Ojeda Bär)

- #14570: Distinguish between prefetching for read and write access in the
  runtime. Significant performance benefit for some multi-domain programs. For
  maximum benefit on AMD64, pass -mprfchw to the C compiler.
  (Nick Barnes, review by Gabriel Scherer, Damien Doligez, and Antonin Décimo)

### Type system:

- #14512: Improve check for warning 16 (unerasable-optional-argument)
  (Alistair O'Brien, review by Florian Angeletti, Gabriel Scherer)

### Code generation and optimizations:

* #13919: optimize `lazy v` when `v` is a structured constant
  (below a size threshold), so that `Lazy.from_val v` should not be
  necessary anymore in most cases.
  This may in theory break certain recursive value declarations,
  in that case switching to `lazy ((); v)` should be enough to
  disable the change in a backward-compatible way.
  (Gabriel Scherer, review by Vincent Laviron)

- #13438: keep some optimization hints from lambda in bytecode modules
  and executables (to be used by Js_of_ocaml / Wasm_of_ocaml)
  (Jérôme Vouillon)

### Standard library:

- #14487: Add String.drop_{prefix,suffix}
  (Michael Neumann, review by Léo Andrès, Nicolás Ojeda Bär and Gabriel Scherer)

- #14553: Add Array.fold_{left,right}2
  (Clément Pottier, review by Nicolás Ojeda Bär and Vincent Laviron)

### Other libraries:

### Tools:

- #14499: in ocamltest, remove support for the legacy
  test syntax (with '***') and the '-translate' option
  to convert from this syntax.
  (Gabriel Scherer, review by Nicolás Ojeda Bär)

- #14502: in ocamltest, `not <action>` negates a
  predicate-like action.
  (Gabriel Scherer, review by Olivier Nicole)

- #14532: in ocamltest, support `<action> && <action>`,
  `<action> || <action>`
  and `if <action> then <action> [else <action>]`.
  (Gabriel Scherer, review by Olivier Nicole)

- #14545: in ocamltest, support `system` variable that uses
  the configure-time @System@ value. Rename the `macos` variable to
  `macosx` to match the configure-time choice.
  (Tim McGilchrist, review by Gabriel Scherer and Antonin Décimo)

### Manual and documentation:

- #14598: Add `@since` annotations to `Runtime_events`. (Raphaël Proust)

### Compiler user-interface and warnings:

- #14205: Make inclusion check error message reference the user-written file
  when operating on a ppx-generated file.
  (Liam Stevenson, review by Florian Angeletti)

- #14142: print GADT equations in error messages when they introduce a type
  (Stefan Muenzel, review by Florian Angeletti)

- #14359, #14600: when reporting unbound type variables in a type declaration,
  avoid a possible confusion between type parameters and unbound variables.
  (Florian Angeletti, report by Florian Weimer, review by Gabriel Scherer)

### Internal/compiler-libs changes:

- #14620: optimize utf8 normalization and (un)capitalization functions
  (Gabriel Scherer, review by Stefan Muenzel and Florian Angeletti,
   report by Stefan Muenzel)

- #14618: optimize utf8 normalization outside of the ASCII range
  (Stefan Muenzel, review by Gabriel Scherer, Daniel Bünzli, and
   Florian Angeletti)

- #14601, remove an unreachable path for unbound type variables in extension
  constructor declarations.
  (Florian Angeletti, review by Gabriel Scherer)

### Build system:

### Bug fixes:

- #14492: Fix Obj.dup on closures.
  (Mark Shinwell and Nick Barnes, review by Gabriel Scherer and Damien Doligez)

OCaml 5.5.0
-----------

(Changes that can break existing programs are marked with a "*")

### Language features:

* #14009: infix extension points/attributes appearing in local structure items,
  eg `let module%foo[@bar] ... in ...` are attached to the AST node of the
  corresponding structure item (similar to their global counterparts) and no
  longer to the enclosing `let` expression.  Extension points/attributes that
  are to be attached to the enclosing `let` expression are to be written next to
  the `let` keyword, eg `let%foo[@bar] module ... in ...`. The same holds for
  `let exception` and `let open`.
  (Nicolás Ojeda Bär, review by Gabriel Scherer)

- #14029: Recognize `%identity` as nonexpansive
  (Stephen Dolan and Olivier Nicole, review by Hugo Heuzard, Jacques Garrigue,
  Jeremy Yallop,  and Gabriel Scherer)

* #13712: Introduce a new kind `Type_external` and syntax
  `type t = external "name"` to discriminate external types from other types
  and each other.  This PR turns primitive types into external and removes the
  past behavior of discriminating abstract types defined in the current module.
  (Takafumi Saikawa, Jacques Garrigue, review by Richard Eisenberg)

- #13806: Enable the use of function parameters with polymorphic types.
  (Ulysse Gérard, Leo White, review by Florian Angeletti, Samuel Vivien, Gabriel
  Scherer and Jacques Garrigue)

- #14040: generalize the constructs `let module`, `let exception` and `let open`
  to most other structure items, eg `let type t = ... in ...`, `let type t +=
  ... in ...`, etc.
  (Nicolás Ojeda Bär, review by Valentin Gatien-Baron)

### Runtime system:

- #14469: Make continuation objects have one field instead of two.
  (KC Sivaramakrishnan, review by Olivier Nicole, Tim McGilchrist, Zane Hambly
  and Ali Caglayan)

- #14416: Spawned domains will record backtraces if the parent domain has
  enabled it.
  (Nathan Taylor, review by Gabriel Scherer)

- #13616: Change free list representation in shared heap
  (Sadiq Jaffer, review by Damien Doligez)

- #13580: Introduce sweep-only phase at start of major GC cycle,
  to reduce latent-garbage delay and therefore improve GC performance.
  (Stephen Dolan and Nick Barnes, review by KC Sivaramakrishnan)

- #14123: Fix integer-overflow problems in heap compaction.
  (Nick Barnes, review by Antonin Décimo).

- #14035: Fix the alignment of _Atomic long long unsigned int fields
  before GCC 11.1 on i686. Silence GCC note on newer versions.
  (Antonin Décimo, review by Sadiq Jaffer)

- #13574, #13594: Generational scanning of stack frames for ARM 64 bits, POWER,
  and RISC-V.  This reduces minor GC work in the presence of deep call stacks.
  (Xavier Leroy, review by Miod Vallat, Gabriel Scherer and Olivier Nicole)

- #14053: Statmemprof: it is now possible to replace a profile in the
  current domain without stopping it in all domains.
  Added the function [Gc.Memprof.is_sampling].
  (Guillaume Munch-Maccagnoni, review by Gabriel Scherer)

- #14168: restore the stack size statistic in `Gc.stat` and adds a new
  `live_stacks_words` field tracking the total size in words of live stacks.
  (Florian Angeletti, review by Gabriel Scherer)

- #14189: Add runtime counters EV_C_MINOR_PROMOTED_WORDS and
  EV_C_MINOR_ALLOCATED_WORDS. EV_C_MINOR_PROMOTED_WORDS reports words promoted
  by minor GC and EV_C_MINOR_ALLOCATED_WORDS reports words allocated by minor
  GC. Both have equivalent bytes counters. Also updated the documentation for
  EV_C_MINOR_PROMOTED and EV_C_MINOR_ALLOCATED to qualify scope of the values
  reported as being per-domain.
  (Tim McGilchrist, review by Nick Barnes, Sadiq Jaffer and
  Gabriel Scherer)

* #14243: Explicit relative paths in ld.conf (".", "..", "./<path...>",
  "../<path...>") are interpreted as being relative to the directory ld.conf
  was loaded from, and the default ld.conf now uses relative paths, rather than
  embedding the absolute path to the Standard Library. The brave may continue to
  put implicit paths in ld.conf. The interpretation of CAML_LD_LIBRARY_PATH is
  unaltered. Additionally, ld.conf is loaded from all of $OCAMLLIB/ld.conf,
  $CAMLLIB/ld.conf and standard_library_default/ld.conf rather than just the
  first one found. ld.conf files with CRLF line endings are now consistently
  normalised on both Windows and Unix.
  (David Allsopp, review by Jonah Beckford, Damien Doligez and Hugo Heuzard)

- #14244: Added --with-relative-libdir which allows the runtime and the
  compilers to locate the Standard Library relative to where the binaries
  themselves are installed, removing the absolute path previously embedded in
  caml_standard_library_default. Executables linked with `ocamlc -custom` now
  always attempt to load bytecode from the executable itself, rather than first
  trying `argv[0]`.
  (David Allsopp, review by Jonah Beckford, Antonin Décimo, Damien Doligez,
   Samuel Hym and Vincent Laviron)

- #14245: Introduce Runtime IDs for use in filename mangling to allow different
  configurations and different versions of the runtime system to coexist
  harmoniously on a single system. The IDs are used, along with the host
  triplet, to provide mangled names for the ocamlrun executable and its variants
  and the DLL versions of both the bytecode and native runtimes, with symlinks
  created for the original names. They are also used to mangle the names of stub
  libraries so that stub libraries compiled for a given configuration of the
  runtime will only be sought by that runtime. The behaviour is disabled by
  configuring with --disable-suffixing.
  (David Allsopp, review by Damien Doligez and Samuel Hym)

- #12269, #12410, #13063: Fix unsafety, deadlocks, and/or leaks should
  rare errors happen during domain creation and thread
  creation/registration.
  (Guillaume Munch-Maccagnoni, review by Gabriel Scherer, B. Szilvasy,
   Miod Vallat)

- #14275: Add function caml_c_thread_register_in_domain, which makes it
  possible to register "C threads" in another domain than 0 (which is
  what caml_c_thread_register does). The function takes a domain unique
  ID in which to register the thread. The domain must be running
  when the function is called.
  (Jack Nørskov Jørgensen, review by Gabriel Scherer,
   Guillaume Munch-Maccagnoni)

- #14337: Fix potential segfault due to the C callback mechanism dropping
  continuations without calling `caml_continuation_use`.
  (Max Slater, review by Nick Barnes and Stephen Dolan)

- #13416: Implement concurrency primitives using WinAPI instead of
  winpthreads on Windows.
  (Antonin Décimo, review by Samuel Hym, Gabriel Scherer, Miod Vallat,
  B. Szilvasy, and Nicolás Ojeda Bär)

- #14367: Gc.Tweak mechanism to allow named GC parameters
  (Stephen Dolan and Nick Barnes, review by Gabriel Scherer, David Allsopp and
  Antonin Décimo)

- #14461: Fix racy socketpair on Windows. Address-in-use errors would sometimes
  occur when concurrent threads or processes were trying to create socketpairs.
  (Jessie Grosen, review by Antonin Décimo and Nicolás Ojeda Bär)

- #14365: Add an Idle phase to the GC for better performance on small
  heaps and for a smooth start at program launch and after a forced major GC.
  (Damien Doligez, review by Stephen Dolan and Nick Barnes)

### Code generation and optimizations:

- #14583: fix bug in linear scan spilling heuristic that in certain situations
  could lead to miscompilations.
  (Nicolás Ojeda Bär, review by Vincent Laviron)

### Standard library:

- #14437: Add String.split_{first,last,all} and String.rsplit_all
  (Daniel Bünzli, review by Nicolás Ojeda Bär and Florian Angeletti)

- #14436: Add String.replace_{first,last,all}
  (Daniel Bünzli, review by Nicolás Ojeda Bär, Ali Caglayan and
   Florian Angeletti)

- #13343: Add Array.stable_sort_sub
  (François Pottier, review by Gabriel Scherer, Corentin Leruth and Nicolás
   Ojeda Bär)

- #14439: Add String.includes
  (Daniel Bünzli, review by Nicolás Ojeda Bär and Olivier Nicole)

- #10177: Seq.(delay : (unit -> 'a t) -> 'a t)
  (Gabriel Scherer, review by Jeremy Yallop and François Pottier)

- #14381: Add String.find_{first,last}_index, String.find_{first,last},
  String.[r]find_all.
  (Daniel Bünzli, review by Nicolás Ojeda Bär, Ali Caglayan and
   Florian Angeletti)

- #14438: Add String.is_empty
  (Daniel Bünzli, review by Nicolás Ojeda Bär and Gabriel Scherer)

- #14440: Add String.of_char
  (Daniel Bünzli, review by Nicolás Ojeda Bär and Gabriel Scherer)

- #14362: Add String.{drop,take,cut}_{first,last}_while
  (Daniel Bünzli, review by Nicolás Ojeda Bär and David Allsopp)

- #14363: Preserve the backtrace at exceptional domain termination. Domain.join
  on an exceptionally terminated domain re-raises the exception with the
  backtrace.
  (KC Sivaramakrishnan, report by Nathan Taylor, review by Gabriel Scherer,
  David Allsopp)

- #13372: New Format and Printf printf-like functions that accept a
   heterogeneous list as arguments.
  (Leonardo Santos, review by Florian Angeletti and Gabriel Scherer)

- #14352: Add String.{drop,take,cut}_{first,last}.
  (Daniel Bünzli, review by David Allsopp, Nicolás Ojeda Bär and
  Vincent Laviron)

- #14185: List.split_map
  (Jeremy Yallop, review by Daniel Bünzli, Nicolás Ojeda Bär and Damien Doligez)

- #13728: Add Sys.runtime_executable containing the full path (if available) to
  the currently executing runtime.
  (David Allsopp, review by Nicolás Ojeda Bär and Daniel Bünzli)

- #13916: Add Option.product and Option.Syntax.
  (Nicolás Ojeda Bär, review by Daniel Bünzli, Gabriel Scherer and David
  Allsopp)

- #13995: Add Option.blend.
  (Kate Deplaix, review by Daniel Bünzli, Gabriel Scherer,
   Nicolás Ojeda Bär, Florian Angeletti and Josh Berdine)

- #14043, #14393: Lazy.Mutexed: simple mutex-protected lazy thunks,
  that may block the entire domain/thread on initialization races.
  (Gabriel Scherer, suggestion by Kate Deplaix and Pierre Chambart,
  review by KC Sivaramakrishnan, Florian Angeletti, Kate Deplaix
  and Daniel Bünzli)

- #14086: Add Domain.count.
  (Nicolás Ojeda Bär, review by David Allsopp, Gabriel Scherer, Daniel Bünzli
  and KC Sivaramakrishnan)

- #13920: add Option.{for_all, exists}
  (Gabriel Scherer, review by Kate Deplaix, Nicolás Ojeda Bär, Richard Eisenberg
  and Jeremy Yallop)

- #12877: Dynarray.rev_iter, Dynarray.rev_iteri
  (Gabriel Scherer, review by Léo Andrès, Jeremy Yallop and Nicolás Ojeda Bär)

- #14118: Add {Set,Map}.S.is_singleton
  (Kate Deplaix, review by Daniel Bünzli, Vincent Laviron, Nicolás Ojeda Bär
   and Stephen Dolan)

- #14060: Add Hashtbl.find_and_replace and Hashtbl.find_and_remove.
  (Sacha-Élie Ayoun, review by Nicolás Ojeda Bär and Gabriel Scherer)

- #14227: Add List.filter_mapi.
  (Émile Trotignon, review by Nicolás Ojeda Bär, Jan Midtgaard and
   Damien Doligez)

- #14084: Future-proof Dynarray implementation against a smarter compiler
  (Basile Clément, review by Gabriel Scherer)

- #14432: Add floor division, ceil division, Euclidean division and remainder
  to the Int, Int32, Int64 and Nativeint modules.
  (Xavier Leroy, review by Ali Caglayan, Nicolás Ojeda Bär, Gabriel Scherer)

- #13101: Add `Fun.todo ()` to signal that a piece of code is not yet
  implemented.
  (Pavlo Khrystenko and Olivier Nicole, review by Daniel Bünzli, Yawar Amin,
   Gabriel Scherer)

- #14433: Add bit-counting functions `leading_zeros`, `leading_sign_bits`,
  `trailing_zeros`, `bit_count`, `unsigned_bitsize`, `signed_bitsize`
  to Int, Int32, Int64, and Nativeint
  (Xavier Leroy, review by Ali Caglayan and David Allsopp)

### Type system:

* #13681, #13682, #13683, #13684, #13275 :
  Introduce a new type `(module M : S) -> t[M]` that corresponds to
  module-dependent functions (aka modular explicits).
  (Samuel Vivien review by Leo White, Gabriel Scherer, Florian Angeletti,
    Jacques Garrigue and Stephen Dolan)

- #13781: Set scope of internal type nodes during abbreviation expansion
  rather than recursing during unification.
  (Jacques Garrigue, review by Gabriel Scherer)

* #14066: catch invalid aliases introduced by signature constraints during
  merging rather than in subtyping:
  ```ocaml
    module X = struct end module F (_:sig end) = struct end
    module type T = (sig module X0 : sig end module X1 = X0 end)
      with module X0 := F(X)
  ```
  Before, it failed with a subtyping error. Now, it fails with a proper error,
  explaining that `X1` would keep an invalid alias to `F(X)`
  (Clement Blaudeau, review by Florian Angeletti)

* #14100: Do not ignore type-constraints and module-constraints when building
  the approximated signature of recursive modules. Ignoring those constraints
  resulted in incorrect (wrong set of fields, wrong shadowing between fields)
  approximated signatures, failing to typecheck, as in:
  ```ocaml
  module X0 : sig type t end
  module rec X : ((sig module A : sig end end) with module A := X0)
  and Y : sig type t = X.A.t end (* Unbound type constructor X.A.t *)
  ```
  Now, type and module constraints are properly merged during approximation ,
  reusing the infrastructure for normal merging of constraints, but disabling
  any wellformedness check.
  (Clement Blaudeau and Ryan Tjoa, review by Florian Angeletti)

- #14327: Allow retyping as-patterns that contain existentials
  (completing #14229)
  (Jacques Garrigue and Takafumi Saikawa, reported by Olivier Nicole,
   review by Gabriel Scherer)

- #14483: Reset type ID and level counters between compilations to restore
  reproducibility of debug information between `ocamlc -c foo.mli foo.ml` versus
  `ocamlc -c foo.mli; ocamlc -c foo.ml`. Also hashcons the identifiers used for
  persistent structures across resets of the type checker. In particular, that
  means the initialisation of globals in Matching do not become observable in
  the marshalled output.
  (David Allsopp, review by Gabriel Scherer)

### Other libraries:

- #13700, #14454: Use POSIX thread-safe getgrnam_r, getgrgid_r, getpwnam_r,
  getpwuid_r, gmtime_r, localtime_r, getlogin_r, and fix mktime error checking.
  (Antonin Décimo, review by David Allsopp, Stefan Muenzel, and Miod Vallat)

- #14406: Better handling of address length for unix sockets, improving Haiku
  compatibility.
  (Sylvain Kerjean, review by Antonin Décimo and Nicolás Ojeda Bär)

* #14046: On Windows, `Unix.kill pid Sys.sigkill` causes the receiving process
  to exit with code ERROR_PROCESS_ABORTED (1067) instead of 0.
  (Nicolás Ojeda Bär, review by Miod Vallat, Antonin Décimo and David Allsopp)

- #14020: Add Unix.unsetenv.
  (Nicolás Ojeda Bär, review by Antonin Décimo and David Allsopp)

- #13447: Symmetrize shared `Sys` and `Unix` functions. Apply fixes
  of #12072, #12184, #12320, and #13166, from `Sys.rename` to
  `Unix.rename`.  Make `caml_sys_close` raise on error, allowing
  `Filename.temp_file` retries if close fails. Flush buffers when
  calling `caml_sys_system_command` on Windows. Error with EINVAL
  instead of ENOENT if the command string is not a valid C string.
  (Antonin Décimo, review by Gabriel Scherer and Nicolás Ojeda Bär)

- #14310: Deprecate union sock_addr_union for struct sockaddr_storage
  and socklen_param_type for socklen_t.
  (Antonin Décimo, review by Nicolás Ojeda Bär, David Allsopp and Samuel Hym)

- #14391: unload native dynlinked objects when an error occurs and it is safe to
  do so. (Fixes #14323)
  (Nicolás Ojeda Bär, review by Vincent Laviron)

### Tools:

- #14055: Invert BUILD_PATH_PREFIX_MAP in directories loaded at startup
  by the debugger.
  (Pierre Boutillier, review by Gabriel Scherer and Daniel Bünzli)

* #13638: ocamlmklib exits with code 4 if passed an unrecognised option, as it
  does with an unrecognised file.
  (David Allsopp, review by Antonin Décimo and Sébastien Hinderer)

- #13941, #13961: Fix `ocamltest` variable handing.
  (Damien Doligez, report by Olivier Nicole, review by Gabriel Scherer)

- #13962: Little ocamltest refactors. Fix error handling in C code,
  leaking file descriptors, code style.
  (Antonin Décimo, review by Gabriel Scherer)

- #14059: Fix flaky TSan tests
  (Fabrice Buoro and Olivier Nicole, review by Gabriel Scherer)

- #13966, #13969: Enable "generalized polymorphic #install_printer"
  in the debugger
  (Pierre Boutillier and Gabriel Scherer, review by Florian Angeletti)

- #14063 : Debugger fallbacks to "looking for 'module_name'.ml in the
  loadpath" when seeking source files. It improves hit rate for
  sources of installed packages.
  (Pierre Boutillier, review by Gabriel Scherer)

- #14032, #14034: Update to and require FlexDLL 0.44.
  (Jan Midtgaard, Antonin Décimo, review by David Allsopp)

- #14239: Fix `#show_constructor` when printing non-GADT type parameters
  (Takafumi Saikawa, Jacques Garrigue, review by Gabriel Scherer)

- #14245: ocamlobjinfo now displays the runtime invoked by a bytecode
  executable (either from the RNTM section or by analysing the shebang lines)
  (David Allsopp, review by Damien Doligez and Samuel Hym)

- #14448: ocamllex now prints a `missing-case` warning and shows an example
  of nonmatching input if a rule is not exhaustive (Martin Jambon,
  review by David Allsopp and Gabriel Scherer)

### Manual and documentation:

- #14397: Improve documentation of type-directed disambiguation of array
  literals (Alicia Michael, review by Olivier Nicole and Florian Angeletti)

- #14293: Improve documentation of Runtime_events.Timestamp (Raphaël Proust,
  review by Gabriel Scherer)

- #13747: Document support for native debugging with GDB and LLDB.
   (Tim McGilchrist, review by Daniel Bünzli, Samuel Hym, Olivier Nicole
   and Antonin Décimo)

* #13975: documented the `[@remove_aliases]` built-in attribute for signatures
  (introduced by #1652 in 2018). Small refactor of the code that fetches the
  attribute.
  (Clement Blaudeau, review by Gabriel Scherer)

- #14002: Add anchors to items and headings of the web version of the API
  documentation for easier linking.
  (Nicolás Ojeda Bär, report by Louis Roché, review by Gabriel Scherer and
  Florian Angeletti)

- #14023: Add documentation for the [row_more] function.
  (Richard Eisenberg, review by Jacques Garrigue)

- #14038: Fall back immediately to user-agent-defined fonts when web fonts
  fail to load.
  (toastal)

- #14048: document modular explicits
  (Gabriel Scherer, review by Samuel Vivien, Ali Caglayan,
   Didier Remy and François Pottier)

- #14077: Add missing `item-attribute` rule for `let-binding`s in documentation
  for attributes.
  (Shon Feder)

- #14228: Trim leading spaces from first lines of LaTeX `ocamldoccode`
  environments.
  (Yukai Chou, review by Nicolás Ojeda Bär)

- #14248: Added documentation about the way `Domain.join` triggers a
  `Thread.join` on the domain's systhreads.
  (Raphaël Proust, review by Gabriel Scherer)

- #14392: Fix AsciiDoc files, add more markup, xrefs, documentation.
  (Antonin Décimo, review by Gabriel Scherer and David Allsopp)

### Compiler user-interface and warnings:

- #12628: Improved error message for unsafe values: print out the full path for
  the value that is unsafe when they are detected during the compilation of
  recursive modules.
  (Shivam Acharya, review by Gabriel Scherer and Florian Angeletti)

- #13994: documentation for external types
  (Gabriel Scherer, review by Jan Midtgaard, Jacques Garrigue
   and Florian Angeletti)

- #14076, 14111: error messages, add a short explanation for mismatched
  universal variables and universal quantifications.
  (Florian Angeletti, review by Gabriel Scherer)

- #14126: Document the `-i-variance` option and `+-`, `-+` variance indicators
  in the reference manual.
  (Takafumi Saikawa, review by Florian Angeletti)

- #14146: add an error message for external declaration with
  a non-syntactic arity
  ```
   external fail: (int -> int as 'a) -> 'a = "%identity"
  ```
  rather than failing with an internal error.
  (Florian Angeletti, review by Gabriel Scherer)

- #14147: print row types in error messages when they are a type constructor,
  e.g. `< foo : int; .. as $0>` when $0 is introduced by a GADT constructor
  (Stefan Muenzel, review by Jacques Garrigue and Florian Angeletti)

- #14190: `ocaml -e` now also processes `-init` (previously it was ignored).
  (Emile Trotignon, review by David Allsopp and @ygrek)

- #14225: do not raise unused-constructor warning on private
  constructor in type implementations, for example
  `type safe = private Safe`, which are typically used to
  create new fresh/generative types (here `safe`) to be used
  as GADT indices.
  (Gabriel Scherer, review by Nicolás Ojeda Bär and Florian Angeletti,
   report by Kate Deplaix)

- #14244: Add -set-runtime-default option to the compiler, allowing the default
  value of the Standard Library location used by the runtime to be overridden.
  (Antonin Décimo, review by David Allsopp, Jonah Beckford, Damien Doligez and
   Samuel Hym)

- #14245: New option -launch-method for ocamlc allows the method used by a
  tendered bytecode executable to locate the interpreter to be given explicitly.
  In particular, it makes it easier to specify the use of the executable
  launcher on Unix. New option -runtime-search extends the bytecode executable
  header to be able to search for the runtime interpreter in the directory
  containing the executable and in PATH rather than relying on a single
  hard-coded path.
  (David Allsopp, review by Damien Doligez and Samuel Hym)

- #14315: enable -i-variance also for classes and extension constructors,
  and add description of -i-variance in manpages
  (Takafumi Saikawa, review by Florian Angeletti and Jacques Garrigue)

- #14373: remove the OCAML_BINANNOT_WITHENV environment variable, and
   always strip typing environment in cmt files
   (Florian Angeletti, review by David Allsopp)

- #14330: add suggestions when a signature mismatch is likely to be be caused by
  spellchecking mistakes, for instance
  ```
      module M: sig type albatross end = struct type albatros end
  ```
  (Malo Monin, Florian Angeletti, review by Gabriel Scherer)

### Internal/compiler-libs changes:

- #13839, #14008: Reimplement `let open`, `let module` and `let exception` in
  terms of a single construct.
  (Nicolás Ojeda Bär, review by Gabriel Scherer, Samuel Vivien, Ulysse Gérard
  and Vincent Laviron, temporary regression reported by Antonio Monteiro)

- #13911, #14117, #14127: Refactor the merging of signature constraints, by
  splitting the monolithic merge function into separate, specialized functions
  (for merging types, modules and module types) - sharing only the recursive
  part for handling deep constraints.
  (Clement Blaudeau, review by Florian Angeletti and Samuel Vivien, fix by Ryan
  Tjoa)

- #13980 Refactor `type-approx` and improve some errors' locations.
  (Leo White, Ulysse Gérard, review by Samuel Vivien and Florian Angeletti)

- #14024: Fix unterminated-string-initialization warnings from the C compiler.
  (Antonin Décimo, review by David Allsopp and Miod Vallat)

- #14094: toplevel, simplify check on installed printer types
  (Florian Angeletti, review by Gabriel Scherer)

- #13656, #14114, #14308: Use C99 stdint.h/inttypes.h fixed-width
  integer types and macros to define OCaml integers.
  (Antonin Décimo, review by Nick Barnes and David Allsopp)

- #14148: Remove an unused field from package_type in typedtree
  (Samuel Vivien, review by Gabriel Scherer)

- #14141: Rename cstrs to constraints when it refers to constraints to avoid
  confusing it with constructors.
  (Stefan Muenzel, review by Nicolás Ojeda Bär)

- #14149: Distinguish `(module M : S)` from `(module M) : (module S)` in
  patterns.
  (Samuel Vivien, review by Gabriel Scherer)

- #14161: refactor the STW-participants machinery to add an intermediate
  category of 'parked' domain structures.
  (Gabriel Scherer, review by Sivaramakrishnan)

- #14198 Constraints on module unpacking are not ghost
  (Thomas Refis, review by Nicolás Ojeda Bär)

- #14243: ocamlc now uses the same code as the runtime to parse ld.conf (via a
  C primitive), eliminating some highly obscure corner cases.
  (David Allsopp, review by Jonah Beckford, Damien Doligez and Hugo Heuzard)

- #14260: Refactor Lambda.structured_constant to avoid duplicate
  representations for string constants
  (Vincent Laviron, review by Nicolás Ojeda Bär and Gabriel Scherer)

- #13913: Use Blake128 as the hash function for the compiler's CRCs
  (Vincent Laviron, review by Xavier Leroy and Gabriel Scherer)

- #14297, #14299: Avoid iterating on hash tables to produce types or terms
  (Vincent Laviron, review by Nicolás Ojeda Bär and Gabriel Scherer)

* #14322: Remove leftover hacks for handling pattern constraints
  As a side effect, `let rec (_ as x) = ...` is now always rejected instead of
  being treated as equivalent to `let rec x = ...`
  (Vincent Laviron, review by Alistair O'Brien and Florian Angeletti)

- #14331: Enforce current_level <= generic_level, and explain create_scope
  (Jacques Garrigue and Takafumi Saikawa, review by Gabriel Scherer)

* #14388: Remove support for `let rec (module M : S) = e1 in e2`.
  (Alistair O'Brien, review by Vincent Laviron and Gabriel Scherer)

- #14413: Introduce and use the C2y countof operator.
  (Antonin Décimo, review by David Allsopp)

- #14422: Refactoring an `if match e with p1 -> true | p2 -> false then ...`
  into a match in typetexp.
  (Samuel Vivien, review by Gabriel Scherer)

- #13224: Clarify barriers and spin macros with delayed expansion.
  (Antonin Décimo, review by David Allsopp and Gabriel Scherer)

- #14435, #14455, #14550: Add the not-root builtin ocamltest action. This
  allows to skip tests that fail if the current user is root (superuser).
  (Kate Deplaix, review by Gabriel Scherer, Nicolás Ojeda Bär, and
   Antonin Décimo)

- #14457: Handle qualified `M.{ x }` patterns in untypeast
  (Basile Clément, review by Florian Angeletti)

- #14120, #14474, #14476: Associate Uids to items that don't have a concrete
  definition
  (Ulysse Gérard, review by Florian Angeletti and Gabriel Scherer)

### Build system:

- #13705, #14444: Cache test results of custom Autoconf tests from aclocal.m4.
  (Antonin Décimo, review by David Allsopp and Miod Vallat)

- #13810: Support build of cross compilers to native freestanding targets
  (Samuel Hym, review by Antonin Décimo and Romain Calascibetta)

- #14243: New configure option --with-additional-stublibsdir allows an
  additional directory to be added to the start of ld.conf. Additionally, the
  stublibs subdirectory is no longer created, nor added to ld.conf, when
  building OCaml with --disable-shared.
  (David Allsopp, review by Jonah Beckford, Damien Doligez and Hugo Heuzard)

- #14244: When targeting native Windows on Cygwin or MSYS2, preserve
  backslashes in the supplied `--prefix` (in particular, backslashes instead of
  slashes will then be displayed by `ocamlopt -config-var standard_library`).
  If the supplied prefix contains a slash, then it is normalised, as
  previously.
  (David Allsopp, review by Jonah Beckford, Antonin Décimo, Damien Doligez and
   Samuel Hym)

- #14245: New --enable-runtime-search configure option controls the
  -runtime-search option used to build the bytecode binaries in the compiler
  distribution. --enable-runtime-search-target controls the default value of
  -runtime-search used for bytecode executables produced by the compiler.
  (David Allsopp, review by Damien Doligez and Samuel Hym)

- #14484: Set `_WIN32_WINNT` to require Windows 8/Server 2012 Windows header SDK
  support.
  (Antonin Décimo, review by David Allsopp)

### Bug fixes:

- #14010: Fix miscompilation / liveness errors for string operations
  (Mark Shinwell, Xavier Clerc, review by Xavier Leroy and Gabriel Scherer)

- #14036: Fix nontermination of cycle printing in recursive modules with
  `-short-paths`. Add error message for types considered abstract while
  checking recursive modules.
  (Brandon Stride, review by Florian Angeletti)

- #14065: Fix function signature mismatch of `__tsan_func_exit` with GCC 15.
  Check in the configure step if the TSan provided internal builtins are the
  same as what we expect, introduce `caml_tsan_*` wrappers for the `__tsan_*`
  functions we use.
  (Hari Hara Naveen S, report by Hari Hara Naveen S,
  review by Gabriel Scherer, Antonin Décimo, Olivier Nicole)

- #14071: Fix exception name in Dynlink.Error printer.
  (Etienne Millon, review by Nicolás Ojeda Bär)

- #13853: Format breaks some line too early when there
  is a break hint at the end.
  (Florian Angeletti, review by Gabriel Scherer)

- #10570: Fix handling of caml_sys_argv when exposed directly as an
  external
  (Keryan Didier, review by Vincent Laviron and Gabriel Scherer)

- #14155: Audit unexecuted phrases in compiler expect tests and
  fix all occurrences
  (Stefan Muenzel, review by Gabriel Scherer)

- #14163, #14176: add a filename location to the deprecation alert for implicit
  uses of libraries bundled with the compiler (unix,re,threads,dynlink)
  (Florian Angeletti, report by Ali Caglayan, review by Gabriel Scherer)

- #14210: fix TSan-reported data race in weak pointers runtime
  (Gabriel Scherer and Damien Doligez, report by Olivier Nicole,
   review by KC Sivaramakrishnan)

- #14213: Fix shadow-stack-related crashes with TSan
  (Olivier Nicole, report by Nathan Taylor, review by Gabriel Scherer and
   Stefan Muenzel)

- #13658, #14181: Fix handling of recursive function types that can result
  in an unbounded number of labeled or optional arguments.
  (Stefan Muenzel, report by Samuel Vivien, review by Florian Angeletti)

- #13777, #14347, #14348, #14421, #14498, #14526: Test that C++
  compilers can link with the OCaml runtime and include its headers.
  (Antonin Décimo, review by David Allsopp and Gabriel Scherer)

- #14255: Fix TSan bug with C calls that take many arguments
  (Olivier Nicole and Miod Vallat, report by Nathan Taylor, review by Gabriel
   Scherer)

- #14230 : ocamltest fails to link test program with -custom in some cases
  (Damien Doligez, review by David Allsopp)

- #14279: -dsource, preserve (mod) and other escaped infix keyword operators in
  the printed source wherever possible.
  (Florian Angeletti, review by Gabriel Scherer)

- #14300, #14304: fix a race between memprof and the minor GC, detected by TSan
  (Gabriel Scherer, review by Stephen Dolan and Nick Barnes,
   report by Olivier Nicole)

- #14384: use the statmemprof status word, rather than a distinguished
   value of a boxed float, to identify a "not really sampling"
   profile.
  (Nick Barnes, review by Gabriel Scherer)

- #14332: Fix missing TSan instrumentation in subexpressions
  (Vincent Laviron, review by Gabriel Scherer and Olivier Nicole)

- #14370, #14429: Fix headers for C++ inclusion.
  (Antonin Décimo, review by Gabriel Scherer)

- #14417: Fix issue with nested packs on macOS.
  (Vincent Laviron, report by Kate Deplaix, review by Gabriel Scherer)

- #14423: Fix detection of SetThreadDescription on 32-bit builds, meaning that
  Thread.set_current_thread_name now works on 32-bit MSVC and uses the correct
  mechanism on 32-bit mingw-w64.
  (David Allsopp, review by Antonin Décimo)

- #14431: Enable native backend for DragonFly BSD. This builds ocamlopt on
  DragonFly.
  (Michael Neumann, review by Gabriel Scherer and Kate Deplaix)

- #14495: Fix infix-tag bug in the minor collector which could cause SEGVs
  in multi-domain programs.
  (Nick Barnes, review by Gabriel Scherer)

- #14519: Fix segfault when using `Runtime_events` under certain
  circumstances due to bad error checking when calling `mmap()`.
  (Mark Elvers, review by Nicolás Ojeda Bär)

- private: robustify intern.c
  (Xavier Leroy and Nicolás Ojeda Bär, review by Olivier Nicole, Mindy Preston,
  Edwin Török, and Gabriel Scherer)

- #13693, #14514: s390x: fix heap corruption with libasmrun_shared.so caused
  by PLT lazy binding trampoline saving FPRs into OCaml's fiber stack.
  Replace @PLT calls with GOT-indirect calls in the s390x code emitter.
  (Zane Hambly, review by David Allsopp and Xavier Leroy)

- #14603, #14604: avoid Ctype.apply failures when mixing
  polymorphic types and unboxed constructors.
  (Gabriel Scherer and Stefan Muenzel, report by Brandon Stride,
   review by Florian Angeletti)

- #14626: Handle module-dependent functions in warning 16 (Reported in #14622).
  (Alistair O'Brien, review by Gabriel Scherer, report by Kate Deplaix)

- #14635: Fix a bug in `caml_floatarray_gather` that would cause
  the result of `Float.Array.sub`, `Float.Array.append`, `Float.Array.concat`
  (when empty) not to be equal to `[||]`.
  (Marc Lasson, review by Gabriel Scherer)

OCaml 5.4.0 (9 October 2025)
----------------------------

(Changes that can break existing programs are marked with a "*")

### Language features:

- #13097: added immutable arrays (`'a iarray` type, Iarray stdlib module)
  (Antal Spector-Zabusky and Olivier Nicole, review by Gabriel Scherer,
  Jeremy Yallop and Vincent Laviron)

- #13340: Array literal syntax [| e1; ...; en |] can now be used to
  denote values of type `'a array` and `'a iarray` and `floatarray`,
  both in expressions and patterns. The compiler disambiguates each
  case by using contextual type information (assuming `'a array`
  by default).
  (Nicolás Ojeda Bär, review by Richard Eisenberg, Jeremy Yallop, Jacques
  Garrigue, and Gabriel Scherer)

- #13498: Tuple fields are now optionally labeled:
  `(x:42, y:0)` and `let (~x, ~y) = ... in ...`.
  (Ryan Tjoa and Chris Casinghino, review by Gabriel Scherer, Chris Casinghino,
  and Leo White)

- RFCs#39, #13404: atomic record fields
    `{ ...; mutable readers : int [@atomic]; ... }`
    `Atomic.Loc.fetch_and_add [%atomic.loc data.readers] 1`
  (Clément Allain and Gabriel Scherer, review by KC Sivaramakrishnan,
   Basile Clément and Olivier Nicole)

### Standard library:

* #14124: Do not raise Invalid_argument on negative List.{drop,take}.
  (Daniel Bünzli, review by Gabriel Scherer, Nicolás Ojeda Bär)

- #13696: Add Result.product and Result.Syntax:
  `let open Result.Syntax in let* x = ... in ...`
  (Daniel Bünzli, review by Gabriel Scherer, Nicolás Ojeda Bär)

- #12871: Add the Pqueue module to the stdlib. It implements priority queues.
  (Jean-Christophe Filliâtre, review by Daniel Bünzli, Léo Andrès and
  Gabriel Scherer)

- #13760: Add String.{edit_distance,spellcheck}
  (Daniel Bünzli, review by wikku, Nicolás Ojeda Bär, Gabriel Scherer and
   Florian Angeletti)

- #13753, #13755: Add Stdlib.Repr:
  Repr.phys_equal and Repr.compare are more explicit than (==) and `compare`.
  (Kate Deplaix, Thomas Blanc and Léo Andrès, review by Gabriel Scherer,
   Florian Angeletti, Nicolás Ojeda Bär, Daniel Bünzli and Jeremy Yallop)

- #13695: Add Stdlib.Char.Ascii
  (Daniel Bünzli, review by Nicolás Ojeda Bär and Jeremy Yallop)


- #13720: Add Result.{get_ok',error_to_failure}
 (Daniel Bünzli, review by wikku, Gabriel Scherer, Nicolás Ojeda Bär,
  Vincent Laviron and hirrolot)

- #13885: Add Dynarray.{exists2, for_all2}.
  (T. Kinsart, review by Daniel Bünzli, Gabriel Scherer, and Nicolás Ojeda Bär)

* #13862: Make List.sort_uniq keep the first occurrences of duplicates.
  (Benoît Jubin, review by Nicolás Ojeda Bär, Gabriel Scherer)

- #13836: Add [Float.]Array.{equal,compare}.
  (Daniel Bünzli, review by Nicolás Ojeda Bär and Gabriel Scherer)

- #13796: Add Uchar.utf_8_decode_length_of_byte and
  Uchar.max_utf_8_decode_length.
  (Daniel Bünzli, review by Nicolás Ojeda Bär and Florian Angeletti)

- #13768: Add Either.get_left and Either.get_right
  (T. Kinsart, review by Nicolás Ojeda Bär and Florian Angeletti)

* #13570, #13794: Format, add an out_width function to Format device for
   approximating unicode width.
  (Florian Angeletti, review by Nicolás Ojeda Bär, Daniel Bünzli,
   and Gabriel Scherer)

- #13731: Add Either.retract
  (Daniel Bünzli, review by Nicolás Ojeda Bär and David Allsopp)

- #13729: Add Seq.filteri
  (T. Kinsart, review by Nicolás Ojeda Bär and Daniel Bünzli)

- #13721: Add Result.retract
  (Daniel Bünzli, review by Gabriel Scherer, Nicolás Ojeda Bär and
   David Allsopp)

- #13310: Add Stdlib.Pair
  (Victoire Noizet, review by Nicolás Ojeda Bär, Daniel Bünzli, Xavier Van de
   Woestyne, Jeremy Yallop and Florian Angeletti)

- #13662: Add eager boolean operations Bool.logand, Bool.logor, Bool.logxor
  (Jeremy Yallop, review by Nicolás Ojeda Bär)

- #13463, #13572: Avoid raising Queue.empty in Format when it is used
  concurrently, raise a specific exception instead.
  (Chritophe Raffalli, review by Gabriel Scherer and Daniel Bünzli)

- #13620: Avoid copying the string in String.concat, String.sub and
  String.split_on_char when the full string is returned.
  (Christophe Raffalli, review by Nicolás Ojeda Bär and Gabriel Scherer and
   Hugo Heuzard)

- #13727: Reimplement Sys.getenv_opt not to use exceptions internally, meaning
  that the current backtrace is preserved when Sys.getenv_opt returns None.
  (David Allsopp, review by Nicolás Ojeda Bär, Josh Berdine and Gabriel Scherer)

- #13737: Avoid closure allocations in Weak.Make.add when resizing the
  table
  (Vincent Laviron, review by Gabriel Scherer and Daniel Bünzli)

- #13740: Improve performance of Weak.find_aux
  (Josh Berdine, review by Gabriel Scherer)

- #13782: Improve performance and type safety of Type.Id by using
  [%extension_constructor] instead of Obj.Extension_constructor.of_val.
  (Basile Clément, review by Vincent Laviron and Nicolás Ojeda Bär)

- #13589: Expose Sys.io_buffer_size, the size of internal buffers used by the
  runtime system and the `unix` library.
  (Yves Ndiaye and Nicolás Ojeda Bär, review by Daniel Bünzli and Nicolás Ojeda
  Bär)

- #13569: add a `Format.format_text` which adds break hints to format literals.
  (Florian Angeletti, review by Nicolás Ojeda Bär, Daniel Bünzli,
   and Gabriel Scherer)

- #13578: On Windows, use the OS CSPRNG to seed the Stdlib.Random generator.
  (Antonin Décimo, review by Miod Vallat, Nicolás Ojeda Bär, and Xavier Leroy)

- #13859: Fix Weak.get_copy not darkening custom blocks
  (Josh Berdine, review by Stephen Dolan)

- #13909: Add `Dynarray.unsafe_to_iarray`
  (Olivier Nicole, review by Daniel Bünzli, Stefan Muenzel and Gabriel Scherer,
  request by Daniel Bünzli)

- #13932: Add List.singleton and Seq.singleton
  (David Allsopp, tariffs applied by Nicolás Ojeda Bär and Gabriel Scherer)

* #13843: Add signal definitions for SIGIO and SIGWINCH. Introduces a
  type alias for signal int, signal_to_string to convert OCaml signal numbers
  to their POSIX equivalent names, and signal_of_int/signal_to_int for
  converting between OCaml and platform signal numbers. (Reported in #13825)
  (Tim McGilchrist, review by David Allsopp, Nicolás Ojeda Bär, Daniel Bünzli,
   Jan Midtgaard and Miod Vallat)

### Runtime system:

- #13500: Add frame pointers support for ARM64 on Linux and macOS.
  (Tim McGilchrist, review by KC Sivaramakrishnan, Fabrice Buoro
   and Miod Vallat)

- #12964: Reintroduce "memory cleanup upon exit" mode. The cleanup will
  however be incomplete if not all domains have been joined when the main
  domain terminates.
  (Miod Vallat, review by KC Sivaramakrishnan, feedback from Nick Barnes
   and Gabriel Scherer)

- #13582: Enable software prefetching support for ARM64, s390x, PPC64 and RiscV.
  Used during GC marking and sweeping to speed up both operations by
  prefetching data.
  (Tim McGilchrist, review by Nick Barnes, Antonin Décimo,
   Stephen Dolan and Miod Vallat)


- #13675: Make Unix.map_file memory show up in Gc.Memprof.
  (Stephen Dolan, review by Guillaume Munch-Maccagnoni and Gabriel Scherer)

- #13785: Add `Runtime_events.Timestamp.get_current`.
  (Simon Cruanes, review by Gabriel Scherer, David Allsopp, Antonin Décimo, Tim
  McGilchrist, Sadiq Jaffer, Vincent Laviron)

- #13774: Fix for inaccurate live blocks/words stats in compaction.
  (Sadiq Jaffer, report by KC Sivaramakrishnan and Jan Midtgaard, review by
  Gabriel Scherer)

- #13773: Ensure that shared pool owners are correctly set on pool adoption.
  (Stephen Dolan, review by Sadiq Jaffer and Gabriel Scherer)

* #11449, #13497: Add caml_stat_char_array_{to,of}_os functions allowing
  conversion of string data which may contain NUL characters. Correct
  implementation of caml_stat_strdup_to_utf16 to raise Out_of_memory instead of
  returning of NULL (the behaviour of caml_stat_strdup_to_os was inconsistent
  between Unix/Windows).
  (David Allsopp, review by Nick Barnes, Antonin Décimo and Miod Vallat)

- #13352: Concurrency refactors and cleanups.
  (Antonin Décimo, review by Gabriel Scherer, David Allsopp, and Miod Vallat)

- #13437: Stop using GetProcAddress to load functions that were not
  available in older, now unsupported Windows versions.
  (Antonin Décimo, review by Nicolás Ojeda Bär and David Allsopp)

- #13470: Constify some function parameters, flags tables, and some
  pointers in C code (take 3).
  (Antonin Décimo, review by Stephen Dolan and Miod Vallat)

- #13492: Parse the CAML_LD_LIBRARY_PATH environment variable for the
  shared_libs_path item in `ocamlrun -config` in addition to displaying the
  entries found in ld.conf.
  (David Allsopp, review by Stephen Dolan)

- #13496: Add missing .type and .size directives to main frametable to silence
  warnings from the linker when using libasmrun_shared on amd64 and power. The
  other backends already carried these directives.
  (David Allsopp, review by Tim McGilchrist and Miod Vallat)

- #13354: Use C99 flexible array member syntax everywhere.
  (Antonin Décimo, review by Miod Vallat, Gabriel Scherer, and Xavier Leroy)

- #11865, #13584: Fix a deadlock triggered by deleting C roots from C finalisers
  (Stephen Dolan, report by Timothy Bourke, review by Mark Shinwell and Damien
  Doligez)

- #13613: Functions from caml/skiplist.h and caml/lf_skiplist.h no longer raise
  Out_of_memory exceptions that the runtime could not handle.
  (Guillaume Munch-Maccagnoni, review by Stephen Dolan)

- #13575, #13635: Maintain OCaml frame pointers correctly even when using
   C libraries that do not support them.
  (Stephen Dolan and David Allsopp, report by Thomas Leonard, review by Tim
   McGilchrist and Fabrice Buoro)

- #13643: Allow values reachable from ephemeron keys to be collected by minor GC
  (Stephen Dolan, review by François Bobot)

- #13701: optimize `caml_continuation_use` based on #12735
  (Hugo Heuzard, review by KC Sivaramakrishnan)

- #13227, #13714: Review of locking in the multicore runtime. Fix
  deadlocks in runtime events and potential deadlocks with named
  values.
  (Guillaume Munch-Maccagnoni, review by Gabriel Scherer, tests by
  Jan Midtgaard)

- #13736: Fix major GC pacing bug triggered by synchronous collections.
  (Nick Barnes, review by Damien Doligez and Tim McGilchrist)

- #13827: Avoid re-marking ephemerons with trivial data.
  (Stephen Dolan, review by Nick Barnes and Josh Berdine, benchmarking by
   Nicolás Ojeda Bär)

- #13300, #13861: introduce `Gc.ramp_up` to explicitly mark ramp-up
  phases of memory consumption and avoid GC overwork. Ramp-up behaviors
  are worse with OCaml 5 than with OCaml 4 due to higher sensitivity
  to excessive pacing computations. Indicating ramp-up explicitly eliminates
  the main known slowdown of OCaml 5 (relative to OCaml 4) for Coq/Rocq.
  (Gabriel Scherer, review by Damien Doligez and Guillaume Munch-Maccagnoni,
   report by Emilio Jesús Gallego Arias and Olivier Nicole)

- #14057: Don't update memprof too early at the end of a minor GC.
  (Nick Barnes, review by Damien Doligez).

- #13629: Major GC ephemeron cleanup.
  (Nick Barnes, review by Stephen Dolan and Tim McGilchrist).

### Code generation and optimizations:

- #13262, #14074: fix performance issue on Apple Silicon macOS by emitting
  `stlr` instead of `dmb ishld; str`.
  (KC Sivaramakrishnan, report by François Pottier, analysis by Frédéric Bour,
  Xavier Leroy, Miod Vallat, Gabriel Scherer and Stephen Dolan, review by Miod
  Vallat, Vincent Laviron and Xavier Leroy)

* #13050, #14104, #14143: Use '$' instead of '.' to separate module names
  in symbol names on macOS and Windows (including the Cygwin backend).
  This changes mangling of OCaml identifiers on those operating systems from
  `camlModule.name_NNN` to `camlModule$name_NNN`. Additionally it
  changes the encoding of special characters from $xx (two hex digits)
  to $$xx (two dollar signs followed by two hex digits).
  (Tim McGilchrist, with contributions from Xavier Leroy,
   reviewed by Xavier Leroy, Miod Vallat, Gabriel Scherer,
   Nick Barnes and Hugo Heuzard)

- #13807: Allow unaligned memory accesses on ARM64.
  (Matthew Else, review by Xavier Leroy)


- #13565: less tagging in switches compiled to affine transformations
  by ocamlopt.
  (Gabriel Scherer and Clément Allain, review by Vincent Laviron,
   report by Vesa Karvonen)

- #13672 Avoid register stall on conversion instructions on amd64.
  (Pierre Chambart, review by Gabriel Scherer and Xavier Leroy,
   report by Patrick Nicodemus)

- #13667: (originally #11162) Fix instr_size computation on arm64.
  (Stephen Dolan and Tim McGilchrist, review by Xavier Leroy
  and David Allsopp)

- #13758: Propagate more value kinds in Flambda to allow more unboxing
  (Vincent Laviron, review by Pierre Chambart)

- #13759: Propagate more type information from clambda to cmm.
  (Pierre Chambart, review by Gabriel Scherer)

- #13735: Follow the behaviour of the C compiler to decide whether to emit the
  `.size` and `.type` directives and the `.note.GNU-stack` section
  (Samuel Hym, review by Miod Vallat, Antonin Décimo and Gabriel Scherer)

### Other libraries:

* #13435: On Windows, use system calls for `Filename.get_temp_dir_name` instead
  of directly reading the environment, which in particular improves the security
  of OCaml processes running in the SYSTEM security context by mitigating
  privileged file operation attacks. For all other processes running with the
  default environment (where `TEMP` is set), there is no discernible change.
  (Antonin Décimo, review by Nicolás Ojeda Bär and David Allsopp)

- #13504, #13625, #14223: Add `Thread.set_current_thread_name`.
  (Romain Beauxis, review by Gabriel Scherer and Antonin Décimo)

* #13376: Allow Dynlink.loadfile_private to load bytecode libraries with
  internal dependencies
  (Vincent Laviron, report by Stéphane Glondu, review by Nicolás Ojeda Bär
   and Xavier Leroy)

- #13429: add `Unix.sigwait`, a binding to the `sigwait` system call;
  implement `Thread.wait_signal` using `Unix.sigwait`, and
  `Thread.sigmask` using `Unix.sigprocmask`.
  (Xavier Leroy, review by Antonin Décimo, Gabriel Scherer, Miod Vallat)

- #13442, #13452: Fix Unix.getgroups for users belonging to more than 32 groups
  when using musl
  (Kate Deplaix, review by Gabriel Scherer, Antonin Décimo, Anil Madhavapeddy)

- #13576: Introduce internal helpers to convert between time representations.
  On Windows, prevent erroneously waiting for an unbounded time in Unix.select
  if more than 64 file descriptors per lists are watched, or if watching
  non-socket file descriptors, and a timeout longer than $2^{32}$ milliseconds
  is used. Cap the timeout to $2^{32}$ milliseconds.
  (Antonin Décimo, review by Gabriel Scherer and Miod Vallat)

- #13921: Set cloexec correctly on CRT file descriptors created by the Unix
  library on Windows. The inheritance on the underlying Win32 handles was
  correctly set, but the book-keeping for the CRT was leaking the value of
  non-inherited handles which combined with reuse of HANDLE values within
  processes could appear to make a CRT file descriptor "re-open".
  (David Allsopp, review by Nicolás Ojeda Bär)

### Tools:

- #13686: Fix Python debugger extensions (for LLDB and GDB) to restore
  functionality broken by #13272 in 5.3.
  (Nick Barnes, review by Tim McGilchrist and Gabriel Scherer)

- #12019: ocamlc: add `align_double` and `align_int64` to `ocamlc -config`
  output.
  (Romain Beauxis, review by David Allsopp)

- #12642, #13536, #14184, #14192: in the toplevel, print shorter paths for
  constructors and labels when only some modules along their path are open.
  (Gabriel Scherer, review by Florian Angeletti)

- #13199, #13485, #13665, #13762, #13965: Support running native debuggers in
  ocamltest.
  (Tim McGilchrist, Sebastien Hinderer, David Allsopp, Antonin Décimo, review by
  Sebastien Hinderer, Gabriel Scherer, Antonin Décimo, and Tim McGilchrist)

- #13764, #13779: add missing "-keywords" flag to ocamldep and ocamlprof
  (Florian Angeletti, report by Prashanth Mundkur, review by Gabriel Scherer)

- #13877: ocamldoc, add a `-latex-escape-underscore` flag to control the
  escaping of `_` underscore in latex references (in order to be able to match
  odoc behaviour).
  (Florian Angeletti, review by Gabriel Scherer)

- #13906: Add support for a `multicore` tag in ocamltest and use it for
  tests that fail on mono-core systems.
  (Stéphane Glondu, review by Nicolás Ojeda Bär)

### Manual and documentation:

- #13751: Document support for profiling with Linux perf and frame pointers.
  (Tim McGilchrist, review by Gabriel Scherer and Miod Vallat)

- #12452: Add examples to Stdlib.Fun documentation.
  (Hazem ElMasry, review by Florian Angeletti and Gabriel Scherer)

- #13924: Document how to put [@deprecated] on let bindings, constructors, etc
  in the manual
  (Valentin Gatien-Baron, review by Florian Angeletti)


- #13694: Fix name for caml_hash_variant in the C interface.
  (Michael Hendricks)

- #13732: Document that custom finalizers must not access the OCaml heap, etc.
  (Josh Berdine, review by Stephen Dolan and Guillaume Munch-Maccagnoni)

### Type system

* #13830: fail rather than silently create abstract module types when avoiding
  (i.e. hiding) signature items, as in:
  ```ocaml
    module N = struct
      open (struct type t = A | B end)
      module type T = sig type u = t * int end
    end
  ```
  Before, it was succeeding with `module N : sig module type T end`, now it
  fails. Similarly for anonymous functor calls (of the form `F(struct ... end))
  (Clement Blaudeau, review by Gabriel Scherer)

### Compiler user-interface and warnings:

- #13817: align spellchecking hints with the possibly misspelled identifier/
              Error: Unbound type constructor "aray"
              Hint:              Did you mean "array"?
  (Florian Angeletti, suggestion by Daniel Bünzli, review by Gabriel Scherer)

- #13587: Enable native backend on x86_64 GNU/Hurd.
  (Samuel Thibault, review by Antonin Décimo, Sébastien Hinderer and Miod
   Vallat)

- #13663: Improve the error message when GADT parameter variance cannot be
  checked.
  (Stefan Muenzel, review by Gabriel Scherer and Florian Angeletti)

- #13646: Improve the error messages when a recursive module type
  references another recursive module type.
  (Stefan Muenzel, review by Florian Angeletti and Gabriel Scherer)

- #13702, #13865: Specialized error messages for functors appearing in contexts
  where non-functors were expected `module A: sig ... end = Set.Make`
  (and the reverse)
  (Florian Angeletti, report by Jeremy Yallop, review by Gabriel Scherer)

- #13788, #13813: Keep the module context in spellchecking hints.
  `Fun.protact` now prompts `Did you mean "Fun.protect?"` rather than
  `Did you mean "protect?"`.
  (Florian Angeletti, suggestion by Daniel Bünzli, review by Gabriel Scherer)


- #13428: support dump=[source | parsetree | lambda | ... | cmm | ...]
  in OCAMLRUNPARAM
  (Gabriel Scherer, review by Vincent Laviron)

- #13493: Clearer error message in ocamlc for conflicting link options for
  C stubs when shared libraries are not available.
  (David Allsopp, review by Gabriel Scherer)

- #13563, lighter inline code styling for output without bold support: inline
  code is no longer printed as "..." to avoid confusion with OCaml strings.
  (Florian Angeletti, review by Richard Eisenberg)

- #13568, composable formatting for warning and alert messages
  (Florian Angeletti, review by Richard Eisenberg)

- #13601: Enable natdynlink on x86_64 GNU/Hurd
  (Samuel Thibault, review by Sébastien Hinderer)

- #13809: Distinguish `(module M : S)` and `(module M) : (module S)` and
  change locations of error messages when `S` is ill-typed in `(module S)`
  (Samuel Vivien, review by Florian Angeletti and Gabriel Scherer)

- #13814, 13898: Add an `unused-type-declaration` warning when using
  a `t as 'a` with no other occurrences of `'a`
  (Samuel Vivien, review by Florian Angeletti, Kate Deplaix)

- #13818: better delimited hints in error message
  (Florian Angeletti, review by Gabriel Scherer)

### Internal/compiler-libs changes:

- #13539, #13776: Use nanosleep instead of usleep or select, if available.
  (Antonin Décimo, review by Miod Vallat and Gabriel Scherer)

- #13748: Add a .editorconfig file for basic editor auto-configuration.
  (Antonin Décimo, review by Gabriel Scherer and David Allsopp)

- #13302, #14236: Store locations of longidents components
  (Ulysse Gérard and Jules Aguillon, review by Jules Aguillon
   and Florian Angeletti)


- #13314: Comment the code of Translclass
  (Vincent Laviron and Nathanaëlle Courant, review by Olivier Nicole)

- #13362: reimplement Floatarray.concat in C (`caml_floatarray_concat`),
  matching the implementation of Array.concat.
  (Gabriel Scherer, review by Nicolás Ojeda Bär)

- #13624: Added location to exception definitions and type extensions
  (Samuel Vivien, review by Gabriel Scherer)

- #13425: undocumented -dmatchcomp flag for the debug
  output of the pattern-matching compiler
  (Gabriel Scherer, review by Vincent Laviron and Nicolás Ojeda Bär)

- #13460: introduce a variant of all predefined types
  (Gabriel Scherer, review by Ulysse Gérard and Florian Angeletti)

- #13457, #13537: Annotate alloc/free open/close pairs of functions
  with compiler attributes for static analysis.
  (Antonin Décimo, review by Gabriel Scherer and Florian Angeletti)

- #13464: Use generic types in call to `subtype`. This improves
  inference of type-directed disambiguation in principal mode.
  (Richard Eisenberg, review by Jacques Garrigue)

- #13606: Fix Numbers.Int_base.compare
  (Mark Shinwell, review by Vincent Laviron)

- #13612: Refactor `type_application`
  (Ulysse Gérard, Leo White, review by Antonin Décimo, Gabriel Scherer,
   Samuel Vivien, Florian Angeletti and Jacques Garrigue)

- #13744: Refactor in `collect_apply_args`
  (Samuel Vivien, review by Florian Angeletti and Gabriel Scherer)

- #13787: a new -dcanonical-ids option to show canonicalized identifier stamps
  in -d{lambda,cmm,...} outputs.
  (Gabriel Scherer, review by Vincent Laviron and David Allsopp,
   suggested by David Allsopp)

- #13820: Add a new option -i-variance to print the variance of every
  type parameter; bivariance is printed as `+-`, and for consistency,
  parser is modified too to accept `+-` and `-+` as `type_variance`.
  (Takafumi Saikawa and Jacques Garrigue, review by Florian Angeletti)

- #13828: Apply BUILD_PATH_PREFIX_MAP to Sys.argv.(0) before storing it in .cmt
  and .cmti files.
  (David Allsopp, review by Daniel Bünzli and Gabriel Scherer)

- #13848: Add all paths components to the cmt files indexes
  (Ulysse Gérard, review by Florian Angeletti)

- #13854: Make the parser set loc_ghost more correctly, for `keyword%extension`
  syntax
  (Valentin Gatien-Baron, review by Florian Angeletti)

- #13856: Add a new indirection in types AST called `package` that stores the
  content of a `Tpackage` node
  (Samuel Vivien, review by Florian Angeletti)

- #13866: Modified occurrence check that prevents recursive types for it to see
  the checked type as a graph rather than a tree
  (Samuel Vivien, report by Didier Remy, review by Florian Angeletti
   and Jacques Garrigue)

- #13884 Correctly index modules in constructors and labels paths
  (Ulysse Gérard, review by Florian Angeletti)

- #13946: refactor the #install_printer code in the debugger and toplevel
  (Pierre Boutillier, review by Gabriel Scherer and Florian Angeletti)

- #13952: check and document the correctness of `caml_domain_alone ()`.
  (Gabriel Scherer, review by KC Sivaramakrishnan, report by Olivier Nicole)

- #13971: Keep generalized structure from patterns when typing `let`
  (Leo White, review by Samuel Vivien and Florian Angeletti)

* #13972: Renamed the `-no-alias-deps` flag internal representation to
  `no_alias_deps` instead of `transparent_modules`.
  (Clement Blaudeau, review by Gabriel Scherer)

### Build system:

* #13526, #13789, #13804: Simplify the build of cross compilers
  This replaces the configure `--with-target-bindir` option by an equivalent
  `TARGET_BINDIR` variable
  (Samuel Hym, review by Miod Vallat, Xavier Leroy, Antonin Décimo and Sébastien
  Hinderer)


- #13431: Simplify github action responsible for flagging PRs with
  the `parsetree-changes` label and extend it to mention the @ppxlib-dev
  team.
  (Nathan Rebours, review by Florian Angeletti)

- #13494: Use native symlinks on Windows for the OCaml installation, reducing
  disk usage considerably.
  (David Allsopp, review by Nicolás Ojeda Bär and Gabriel Scherer)

- #13789: Strictly validate the host and target triplets when building for the
  Windows ports to be *-*-cygwin, *-w64-mingw32* or *-pc-windows. Other Cygwin
  variants used to be rejected - other MSVC and mingw-w64 variants are now
  rejected too.
  (David Allsopp, review by Antonin Décimo and Gabriel Scherer)

### Bug fixes:

- #14574, #14577, #14589: Fix wrong assembly code generated for ARM64
  with frame pointer support.
  (Xavier Leroy, review by Vincent Laviron, report by Richard Jones)

- #13819: Fix field initialisation bug in runtime events subsystem.
  (Nick Barnes, review by Gabriel Scherer).

- #13977: Pass `-fPIC` when compiling C files using `ocamlopt`. This was a
  regression in OCaml 5.3.
  (Nicolás Ojeda Bär, review by Daniel Bünzli and Gabriel Scherer)

- #13957: Allow 'effect' as attribute id.
  (Pieter Goetschalckx, review by Nicolás Ojeda Bär and Florian Angeletti)

- #13691 #13895: Make four globals underlying Gc.control atomic to avoid C data
  races against them.
  (Jan Midtgaard, review by Miod Vallat, Sadiq Jaffer and Antonin Décimo)

- #13454: Output a correct trace of the C_CALLN bytecode.
  (Miod Vallat, review by Antonin Décimo)

- #13595: Use x19 as Canonical Frame Address (CFA) register. This would cause
  backtraces to be truncated when calling no alloc C code.
  (Tim McGilchrist, report by Nick Barnes, review by Nick Barnes)

* #13605: Fix ungenerated constraints when they where impossible due to polyvars
  issues
  (Samuel Vivien, review by Florian Angeletti, Richard Eisenberg
   and Jacques Garrigue)

- #13677, #13679: domain.c: remove backup_thread_running to simplify
  concurrent state updates to the backup thread status.
  (Gabriel Scherer, review by Jan Midtgaard and Miod Vallat,
   report by Jan Midtgaard)

- #13896, #14098: ocamldoc, do not wrap module description in a paragraph tag
  inside the table of modules
  (Florian Angeletti, report by John Whitington, review by Gabriel Scherer)

- #13703: wrong explanation for some polymorphic-variant subtyping errors
  (Gabriel Scherer, review by Jacques Garrigue,
   report by Wiktor Kuchta and Richard Eisenberg)

- #13710: Support unicode identifiers in comments.
  (Pieter Goetschalckx, review by Florian Angeletti and Gabriel Scherer)

- #13763: Track type of variables bound by as-patterns
  (Leo White, review by Gabriel Scherer, port by Vincent Laviron)

- #13778, #13811: do not warn for unused type declarations when the type is used
  in a first-class module type (`module S with type t = int)`.
  (Florian Angeletti, report by Nicolás Ojeda Bär, review by Gabriel Scherer)

- #13790: Fix bytecode-only build of Cygwin when flexlink is being bootstrapped
  with the compiler.
  (David Allsopp, review by Antonin Décimo and Miod Vallat)

- #13812: Add forgotten check about the validity of the type variable name on
  the right-hand side of `_ as _`.
  (Samuel Vivien, review by Gabriel Scherer)

- #13845: Fix bug in untypeast/pprintast for value bindings with polymorphic
  type annotations.
  (Chris Casinghino, review by Florian Angeletti and Gabriel Scherer)

- #13930, #13933: Fix bugs in recursive values definitions involving
  lazy values that have already been evaluated.
  (Gabriel Scherer, review by Vincent Laviron, report by Vincent Laviron)

- #13867: Fix bug with some recursive bindings of lazy values.
  (Guillaume Bury and Vincent Laviron, review by Stefan Muenzel
   and Gabriel Scherer)

- #13931: fix bugs in nested recursive value definitions.
  (Gabriel Scherer, review by Vincent Laviron,
   report by Vincent Laviron)

- #13875, #13878: Add dedicated constructor for mutable variable access in
  Cmm to prevent bugs linked to incorrect handling of coeffects.
  (Vincent Laviron, review by Gabriel Scherer)

- #13880: Make object stat counters atomic
  (Dimitris Mostrous, review by Gabriel Scherer and Nicolás Ojeda Bär)

- #13172, #13829: Fix a missing check of illegal recursive module-type
  definitions
  (Clement Blaudeau, review by Florian Angeletti)

- #13541, #13777: Using C++11 `thread_local` causes name-mangling
  issues when linking with flexlink on Cygwin.
  (Antonin Décimo and David Allsopp, report by Kate Deplaix)

* #13874, #13882: Make evaluation order consistent for applications when using
  the non-flambda native compiler
  (Vincent Laviron, report by Jean-Marie Madiot, review by Gabriel Scherer)

- #13942: Fix assertion on empty array case
  (Olivier Nicole, review by Gabriel Scherer)

- #13950: Avoid tearing in `Array.sub`
  (Gabriel Scherer and Olivier Nicole, report by Jan Midtgaard, review by
   Gabriel Scherer)

- #13928, #13944: Fix handling of excessively nested unboxed types
  (Vincent Laviron, review by Gabriel Scherer)

- #13987: Remove a spurious TSan report in case of benign data race between
  major GC read and write from the mutator (fixes #13427)
  (Olivier Nicole, report by Thomas Leonard, review by Gabriel Scherer)

- #14007, #14015: Fix memory corruption when an exception is raised during
  demarshaling.
  (Benoît Vaugon, review by David Allsopp and Gabriel Scherer)

- #14025: fix data race between compaction and domain termination
  (Gabriel Scherer, review by Jan Midtgaard,
   report by Jan Midtgaard)

- #13956 Fix a regression introduced in #13308 triggering wrong unused warnings.
  (Ulysse Gérard, review by Florian Angeletti)

- #14070: also point to label mismatches in error messages for labelled tuples
  (Florian Angeletti, review by Gabriel Scherer)

- #14088, #14091: fix non-deterministic code generation in
  matching.ml (backport of rescript-lang/rescript#7557)
  (Christiano Calgano, review by Gabriel Scherer and Vincent Laviron)

- #14105: Fix a loop in Pprintast that could result in a hang when printing
  constructor `(::)` in isolation.
  (Ulysse Gérard, review by Nicolás Ojeda Bär and Florian Angeletti)

- #14108: toplevel, fix a typo in directive type mismatch
  (Florian Angeletti, review by Gabriel Scherer)

- #13586, #14093: Fix closing an out_channel during flush
  (Stephen Dolan, report by Jan Midtgaard, investigation by Nick Roberts,
   review by Antonin Décimo and Miod Vallat)

- #14101, #14139: define atomic helper types inside `caml/misc.h` to improve
  header compatibility with C++
  (Florian Angeletti, report by Kate Deplaix, review by Gabriel Scherer)

- #14135: Fix a rare internal typechecker error when combining recursive
  modules, polymorphic fields or methods, and constrained type parameters.
  (Florian Angeletti, review by Gabriel Scherer)

- #14169: runtime, fix cache miss within the stack fragments cache
  (Florian Angeletti, review by Gabriel Scherer)

- #14196, #14197: ocamlprof: do not instrument unreachable clauses
  (Gabriel Scherer, review by Nicolás Ojeda Bär, report by Ali Caglayan)

- #14200, #14202 : bad variance check with private aliases
  (Jacques Garrigue, report and review by Stephen Dolan)

- #14061, #14209: fix a memory-ordering bug in Weak.set that could
  result in uninitialized memory seen by Weak.get on another domain.
  (Damien Doligez, review by Gabriel Scherer)

- #14214, #14221: fix a confused error message for module inclusions,
  functor error messages were missing some type equalities potentially leading
  to nonsensical "type t is not compatible with type t" submessage
  (Florian Angeletti, report by Basile Clément, review by Gabriel Scherer)

- #14238: Fix certain variadic macros in misc.h which could trigger C warnings
  under certain conditions in prerelease versions of OCaml 5.4.
  (Antonin Décimo, review by Nicolás Ojeda Bär)

- #14287: Bugfix for GC root mishandling in memprof.c
  (Stephen Dolan, review by Leo White)

- #14368: Bugfix for Simplif substituting under lambda
  (Stephen Dolan, review by Vincent Laviron
   and Gabriel Scherer)

OCaml 5.3.0 (8 January 2025)
----------------------------

(Changes that can break existing programs are marked with a "*")

### Restored backend:

- #12954: Restore the MSVC port
  (David Allsopp, Antonin Décimo, Samuel Hym, and Miod Vallat, review by Nicolás
   Ojeda Bär)

- #13093: Allow building the MSVC port with clang-cl.
  (Antonin Décimo, review by Nicolás Ojeda Bär, Samuel Hym,
   David Allsopp and Sébastien Hinderer)

### Language features:

- #12309, #13158: Add syntax support for deep effect handlers
  (Leo White, Tom Kelly, Anil Madhavapeddy, KC Sivaramakrishnan, Xavier Leroy
   and Florian Angeletti, review by the same, Hugo Heuzard, and Ulysse Gérard)

- #11736, #12664, #13628: Support utf-8 encoded source files and latin-9
  compatible identifiers.
  (Xavier Leroy and Florian Angeletti, review by Daniel Bünzli and
   Jules Aguillon)

- #12828, #13283: Add short syntax for dependent functor types `(X:A) -> ...`
  (Jeremy Yallop, review by Nicolás Ojeda Bär and Gabriel Scherer)

### Type system

- #11891, #12507: Allow to name new locally abstract types in constructor type
  annotations.
  (Jacques Garrigue, report and review by Gabriel Scherer and Florian Angeletti)

### Runtime system:

- #11911, #12923: Multicore statistical memory profiling.
  This restores a notable OCaml 4 feature that was missing
  in OCaml 5.
  (Nick Barnes, review by Stephen Dolan, Jacques-Henri Jourdan
   and Guillaume Munch-Maccagnoni).


- #13419: Fix memory bugs in runtime events system.
  (B. Szilvasy and Nick Barnes, review by Miod Vallat, Nick Barnes,
   Tim McGilchrist, and Gabriel Scherer)

- #13364: Emit major slice counters in the runtime events.
  (KC Sivaramakrishnan and Sadiq Jaffer, review by Gabriel Scherer)

- #13382: Add more documentation for Runtime_events types
  (Sadiq Jaffer, review by Tim McGilchrist, Miod Vallat and KC Sivaramakrishnan)

- #13370: Fix a low-probability crash when calling Gc.counters.
  (Demi Marie Obenour, review by Gabriel Scherer)

- #13272: Allow maximum number of domains to be specified as a OCAMLRUNPARAM
  parameter.
  (KC Sivaramakrishnan, review by Guillaume Munch-Maccagnoni, Miod Vallat,
   Gabriel Scherer, David Allsopp, request by Zachary Yedidia).

- #12579: OS-based Synchronisation for Stop-the-World Sections
  (B. Szilvasy, review by Miod Vallat, Nick Barnes, Olivier Nicole,
   Gabriel Scherer and Damien Doligez)

- #12789: Restore caml_unregister_frametable from OCaml 4
  (Frédéric Recoules, review by Gabriel Scherer)

- #13003: new, more consistent names for array-creation C functions
  (Gabriel Scherer, review by Olivier Nicole)

- #13013: introduce a `caml_result` type to supersede the
  use of 'encoded exception values' in the FFI.
  (Gabriel Scherer, review by Damien Doligez,
   Guillaume Munch-Maccagnoni and Xavier Leroy,
   suggested by Guillaume Munch-Maccagnoni)

- #12407, #13226: Resource-handling improvements: add
  exception-returning variants for all exception-raising functions in
  `caml/fail.h`, for the purpose of cleaning-up state and resources
  before raising.
  (Guillaume Munch-Maccagnoni, review by Damien Doligez, Xavier Leroy
   and Gabriel Scherer)

- #13086: Avoid spurious major GC slices.
  (Damien Doligez, report by Stephen Dolan, review by Gabriel Scherer
   and Stephen Dolan)

- #11779, #13117: Improve logic for fiber stack alignment.
  (Miod Vallat, report by Damien Doligez, review by Gabriel Scherer)

- #12839: Remove ATOMIC_UINTNAT_INIT from camlatomic.h (as part of a larger
  cleanup of camlatomic.h)
  (David Allsopp, review by Antonin Décimo, Sébastien Hinderer, Samuel Hym,
   Guillaume Munch-Maccagnoni and Miod Vallat)

- #13163: Enable frame pointers on macOS x86_64
  (Tim McGilchrist, review by Sébastien Hinderer and Fabrice Buoro)

- #12951: Constify constructors and flags tables in C code (take 2).
  Now these tables will go in the readonly segment, where they belong.
  (Antonin Décimo, review by David Allsopp)

- #10696: Introduce __has_attribute and __has_c_attributes in
  <caml/misc.h> to test the support of specific attributes in C
  code. Introduce fallthrough as a wrapper around the fallthrough
  attribute.
  (Antonin Décimo, review by Nicolás Ojeda Bär, Xavier Leroy, and
   Gabriel Scherer)

- #13083: Use macros from limits.h to avoid signed-integer wrap-around.
  Introduce CAML_{U,}INTNAT_{MIN,MAX} macros to expose {u,}intnat limits.
  (Antonin Décimo, review by Nick Barnes, Xavier Leroy, Gabriel Scherer,
   and Miod Vallat)

- #13239: Check whether the compiler supports the labels as values
  extension to enable threaded code interpretation.
  (Antonin Décimo, review by Miod Vallat)

- #13238: Enable software prefetching on x86 and x86_64 when building
  with MSVC or clang-cl.
  (Antonin Décimo, review by Miod Vallat)

- #13241, #13261, #13271: Add CFI_SIGNAL_FRAME to ARM64 and RiscV runtimes,
  for the purpose of displaying backtraces correctly in GDB.
  (Tim McGilchrist, review by Miod Vallat, Gabriel Scherer and
   KC Sivaramakrishnan)

- #13139: Simplify CAMLalign to always use C23/C++11 alignas or C11
  _Alignas. Ensures that stat data is always aligned to the best
  boundary.
  (Antonin Décimo, review by Miod Vallat and Xavier Leroy)

- #13280: Check for support of compiler attributes. Allows using
  compiler attributes with clang-cl.
  (Antonin Décimo, review by Miod Vallat)

- #13243: Enable C compiler warnings internally when building with
  clang-cl or MSVC. Provide fixes too.
  (Antonin Décimo, review by Miod Vallat and Xavier Leroy)

- #13242: Define and use unreachable and trap annotation, and clean-up some
  runtime assertions.
  (Antonin Décimo, review by Miod Vallat, Gabriel Scherer, and David Allsopp)

- #13402, #13512, #13549, #13553: Revise bytecode implementation of callbacks
  so that it no longer produces dangling registered bytecode fragments.
  (Xavier Leroy, report by Jan Midtgaard, analysis by Stephen Dolan,
   review by Miod Vallat)

- #13407: Add Runtime_events.EV_EMPTY_MINOR.
  (Thomas Leonard, review by KC Sivaramakrishnan, Sadiq Jaffer and
  Gabriel Scherer)

- #13522: Confirm runtime events ring is still active after callback.
  (KC Sivaramakrishnan, review by Sadiq Jaffer and Miod Vallat)

- #13529: Do not write to event ring after going out of stw participant set.
  (KC Sivaramakrishnan, review by Sadiq Jaffer)

### Code generation and optimizations:

- #13014: Enable compile-time option -function-sections on all previously
  unsupported native backends (POWER, riscv64 and s390x)
  (Miod Vallat, review by Nicolás Ojeda Bär)

- #7241, #12555, #13076, #13138, #13338, #13152, #13153, #13154:
  fix a soundness bug in the pattern-matching compiler
  when side-effects mutate the scrutinee during matching.
  (Gabriel Scherer, review by Nick Roberts)

- #13341: a warning when the pattern-matching compiler pessimizes code
  because side-effects may mutate the scrutinee during
  matching. (This warning is disabled by default, as this rarely
  happens and its performance impact is typically not noticeable.)
  (Gabriel Scherer, review by Nick Roberts, Florian Angeletti
   and David Allsopp)

- #13179: Fix evaluation of toplevel lets in classes containing
  local opens
  (Vincent Laviron, review by Hugo Heuzard, Nathanaëlle Courant
   and Gabriel Scherer)

- #13543: Remove some String-Bytes conversion from the stdlib to behave better
  with js_of_ocaml
  (Hugo Heuzard, review by Gabriel Scherer)

### Standard library:

- #12885: move Dynarray to an unboxed representation
  (Gabriel Scherer, suggestions by Vincent Laviron,
   review by Olivier Nicole and Simon Cruanes, Yann Leray, Alain Frisch)


- #12884: Add `Queue.drop`
  (Léo Andrès, review by Nicolás Ojeda Bär and Gabriel Scherer)

- #13168: In Array.shuffle, clarify the code that validates the
  result of the user-supplied function `rand`, and improve the
  error message that is produced when this result is invalid.
  (François Pottier, review by Florian Angeletti, Daniel Bünzli
   and Gabriel Scherer)

- #12133: Expose support for printing substrings in Format
  (Florian Angeletti, review by Daniel Bünzli, Gabriel Scherer
   and Nicolás Ojeda Bär)

- #12869: Add List.take, List.drop, List.take_while and List.drop_while
  (Kate Deplaix and Oscar Butler-Aldridge, review by Nicolás Ojeda Bär,
   Craig Ferguson and Gabriel Scherer)

- #13047: Add Sys.poll_actions to (only) run pending runtime actions.
  (Nick Barnes, review by Gabriel Scherer, Guillaume Munch-Maccagnoni, and
  Vincent Laviron)

- #13144: Dynarray.{equal, compare}
  (Gabriel Scherer,
   review by Jeremy Yallop, Daniel Bünzli and Olivier Nicole,
   request by Olivier Nicole)

- #13171: expose `Domain.self_index : unit -> int` (a somewhat-dense
  indexing of currently-running domains) for advanced use-cases of
  domain-indexed concurrent data structures.
  (Gabriel Scherer,
   review by KC Sivaramakrishnan, Miod Vallat and Nicolás Ojeda Bär,
   report by Vesa Karvonen)

- #13197: Dynarray.blit, which allows to extend the destination
  dynarray (0 <= dst_pos <= dst_length).
  (Gabriel Scherer, report by Hazem ElMasry,
   review by Olivier Nicole, Hazem ElMasry and Nicolás Ojeda Bär)

* #13240: Add Uchar.seeded_hash, Change Uchar.hash implementation.
  Previously, Uchar.hash was aliased to Uchar.to_int. If you need that behavior,
  change your module instantiation from eg `module HT = Hashtbl.Make(Uchar)` to
  ```
    module HT = Hashtbl.Make(struct
      ...
      let hash = Uchar.to_int
    end)
  ```
  If the current implementation is desired, and you have a hashtable module `HT`
  (produced with the `Make` functor) in persistent storage, use `HT.rebuild` to
  ensure it doesn't break when reading from or writing to buckets.
  (Hazem ElMasry, review by Gabriel Scherer and Nicolás Ojeda Bär)

- #13318: Fix regression in GC alarms, and fix them for flambda.
  (Guillaume Munch-Maccagnoni, report by Benjamin Monate, review by
   Vincent Laviron and Gabriel Scherer)

- #13296: Add mem, memq, find_opt, find_index, find_map and find_mapi
  to Dynarray.
  (Jake H, review by Gabriel Scherer and Florian Angeletti)

### Other libraries:

- #11996: release the dependency of dynlink on compilerlibs.
  (Sébastien Hinderer and Stephen Dolan, review by Damien Doligez and
  Hugo Heuzard)

- #13326: Implement Unix.O_APPEND on windows.
  (Romain Beauxis, review by Miod Vallat, Gabriel Scherer and Antonin Décimo)

### Tools:

- #11716: ocamllex: mismatched parentheses and curly brackets are now caught
  by ocamllex, instead of causing invalid OCaml code to be generated.
  (Demi Marie Obenour, review by Damien Doligez and Xavier Leroy)

- #12904: Run the testsuite with ThreadSanitizer on a PR when label
  `run-thread-sanitizer` is added
  (Olivier Nicole, suggested by Sébastien Hinderer and David Allsopp, review by
   Gabriel Scherer)

* #13114: Support ocamldebug remote debugging over IPv6 on all
  platforms, and over Unix domain sockets on Windows.
  (Antonin Décimo, review by Gabriel Scherer and Miod Vallat)

- #13136: Rewrite GDB extensions and macros in debugger-agnostic Python, and add
  LLDB support for them.
  (Nick Barnes, review by Tim McGilchrist and Gabriel Scherer)

- #14375: More accurate error message in the ocamldebug in case of incorrect or
  missing magic number.
  (Alex Asafov, review by Gabriel Scherer)

### Toplevel:

- #12891: Improved styling for initial prompt
  (Florian Angeletti, review by Gabriel Scherer)

- #13053: Improved display of builtin types such as `_ list` when aliased.
  (Samuel Vivien, review by Florian Angeletti)

### Manual and documentation:

- #13370: Document that temporary variables holding GCd pointers must
  not be live across a GC.
  (Demi Marie Obenour)

- #12298: Manual: emphasize that Bigarray.int refers to an OCaml integer,
  which does not match the C int type.
  (Edwin Török, review by Florian Angeletti)

- #12868: Manual: simplify style colours of the post-processed manual and API
  HTML pages, and fix the search button icon
  (Yawar Amin, review by Simon Grondin, Gabriel Scherer, and Florian Angeletti)

- #12949: document OCaml release cycles and version strings in
   `release-info/introduction.md`.
  (Florian Angeletti, review by Fabrice Buoro, Kate Deplaix, Damien Doligez, and
   Gabriel Scherer)

- #12976: Manual: use webman/<version>/*.html and
  webman/<version>/api/ for OCaml.org HTML manual generation
  (Shakthi Kannan, review by Hannes Mehnert, and Florian Angeletti)

- #13045: Emphasize caution about behaviour of custom block finalizers.
  (Nick Barnes)

- #13216: document the new `caml_result` type in the FFI chapter of the manual.
  (Gabriel Scherer, review by Miod Vallat, Daniel Bünzli, Nick Barnes,
   Guillaume Munch-Maccagnoni and Antonin Décimo)

- #13287: stdlib/sys.mli: Update documentation on Sys.opaque_identity
  following #9412.
  (Matt Walker, review by Guillaume Munch-Maccagnoni and Vincent Laviron)

- #13295: Use syntax for deep effect handlers in the effect handlers manual
  page.
  (KC Sivaramakrishnan, review by Anil Madhavapeddy, Florian Angeletti and Miod
   Vallat)

- #13424: Fix `Gc.quick_stat` documentation to clarify that returned fields
  `live_words`, `live_blocks`, `free_words`, and `fragments` are not zero.
  (Jan Midtgaard, review by Damien Doligez and KC Sivaramakrishnan)

- #13440: Update documentation of `Gc.{control,get,set}` to reflect fields
  not currently supported on OCaml 5.
  (Jan Midtgaard, review by Gabriel Scherer)

- #13469, #13474, #13535: Document that [Hashtbl.create n] creates a hash table
  with a default minimal size, even if [n] is very small or negative.
  (Antonin Décimo, Nick Barnes, report by Nikolaus Huber and Jan Midtgaard,
   review by Florian Angeletti, Anil Madhavapeddy, Gabriel Scherer,
   and Miod Vallat)

- #13666: Rewrite parts of the example code around nested lists in Chapter 6
  (Polymorphism and its limitations -> Polymorphic recursion) giving the
  "depth" function [in the non-polymorphically-recursive part of the example]
  a much more sensible behavior; also fix a typo and some formatting.
  (Frank Steffahn, review by Florian Angeletti)

- #13668: Document the basic support for unicode identifiers and the switch to
   UTF-8 encoded Unicode text for OCaml source file
  (Florian Angeletti, review by Nicolás Ojeda Bär and Daniel Bünzli)

### Compiler user-interface and warnings:

* #12084, #13669, #13673: Check link order when creating archive and when using
   ocamlopt.
  (Hugo Heuzard, review by Stefan Muenzel and Sébastien Hinderer)

- #12980: Explain type mismatch involving first-class modules by including
  the module level error message
  (Florian Angeletti, review by Vincent Laviron)

- #12985, #12988: Better error messages for partially applied functors.
  (Florian Angeletti, report by Arthur Wendling, review by Gabriel Scherer)

- #13034, #13260: Better error messages for mismatched function labels
  (Florian Angeletti, report by Daniel Bünzli, review by Gabriel Scherer and
   Samuel Vivien)

- #13051: Add a "Syntax error" to error messages for invalid package signatures.
  (Samuel Vivien, review by Gabriel Scherer)

- #13099: Fix erroneous loading of cmis for some module type errors.
  (Nick Roberts, review by Florian Angeletti)

- #13151, name conflicts explanation as a footnote
  (Florian Angeletti, review by Gabriel Scherer)

- #13228: Re-export Cmt2annot.{iterator,binary_part} which had become hidden
  since #11288 and broke ocamlbrowser.
  (David Allsopp, report by Jacques Garrigue, review by Sébastien Hinderer)

- #13251: Register printer for errors in Emitaux
  (Vincent Laviron, review by Miod Vallat and Florian Angeletti)

- #13255: Re-enable warning 34 for unused locally abstract types
  (Nick Roberts, review by Chris Casinghino and Florian Angeletti)

- #12182: Improve the type clash error message.
  For example, this message:
    This expression has type ...
  is changed into:
    The constant "42" has type ...
  (Jules Aguillon, review by Gabriel Scherer and Florian Angeletti)

- #13471: add `-keywords <version?+list>` flag to define the list of keywords
  recognized by the lexer, for instance `-keywords 5.2` disable the `effect`
  keyword.
  (Florian Angeletti, review by Gabriel Scherer)

### Internal/compiler-libs changes:

- #13286: Distinguish unique identifiers `Shape.Uid.t` according to their
  provenance: either an implementation or an interface.
  (Ulysse Gérard, review by Florian Angeletti and Leo White)

- #13308: keep track of relations between declaration in the cmt files. This is
  useful information for external tools for navigation and analysis purposis.
  (Ulysse Gérard, Florian Angeletti, review by Florian Angeletti and Gabriel
  Scherer)


- #11129, #11148: enforce that ppxs do not produce `parsetree`s with
  an empty list of universally quantified type variables
  (`. int -> int` instead of `'a . int -> int'`)
  (Florian Angeletti, report by Simmo Saan, review by Gabriel Scherer)

- #12534: document and refactor Matching.mk_failaction_pos
  (Gabriel Scherer, review by Vincent Laviron and Nick Roberts)

- #13076: change the handling of Match_failure exits in the pattern-matching
  compiler, to prepare for a complete fix for #7241
  (Gabriel Scherer, review by Thomas Refis and Nick Roberts)

- #12896: Simplify the compilation of custom bytecode runtimes by explicitly
  compiling the primitives file before calling the linker. Tidy-up both the
  generating code and the output itself for C code being generated by the
  bytecode linker in `-custom` and `-output-*` modes.
  (David Allsopp, Antonin Décimo and Samuel Hym, review by Vincent Laviron)

- #12932: Remove useless code in Typecore.type_label_exp (was a fix for #4862)
  (Jacques Garrigue, review by Gabriel Scherer)

- #12943: Make transient_expr.scope a bitfield, and use it to store marks.
  Marks are automatically allocated, and removed when leaving their scope.
  Falls back to using TransientTypeSet when marks are exhausted.
  (Jacques Garrigue and Takafumi Saikawa, review by Basile Clément)

- #12946: Make generalization automatic when leaving scope.
  As a result, the `Ctype.generalize*` and `Ctype.correct_levels` functions
  were removed. The latter is now called `Ctype.duplicate_type`.
  (Jacques Garrigue and Takafumi Saikawa, review by Richard Eisenberg)

- #12968: Attach location to constants in the parsetree
  (Jules Aguillon, review by Gabriel Scherer)

- #12959, #13055: Avoid an internal error on recursive module type inconsistency
  (Florian Angeletti, review by Jacques Garrigue and Gabriel Scherer)

- #13049: graphical debugging printer for types
  (Florian Angeletti, review by Gabriel Scherer)

- #13074, #13082, #13084: refactoring in the pattern-matching compiler
  (Gabriel Scherer, review by Thomas Refis, Vincent Laviron and Nick Roberts)

- #13067: rework volatile memory access rules under TSan to consider properly
  aligned smaller-than-register read operations as atomic, which gets rid of
  false positives on s390x
  (Miod Vallat, review by Fabrice Buoro)

- #13162: Use quoted strings to clarify code being generated.
  (Antonin Décimo, review by Miod Vallat and Gabriel Scherer)

- #13015: Emit floating-point literals in .rodata section on ELF arm64
  platforms (Linux, *BSD).
  (Miod Vallat, review by Nicolás Ojeda Bär)

- #13169, #13311: Introduce a document data type for compiler messages
  rather than relying on `Format.formatter -> unit` closures.
  (Florian Angeletti, review by Gabriel Scherer)

- #13193: Remove the unused env_init field from class blocks
  (Vincent Laviron, review by Jacques Garrigue)

- #13257: integrate MetaOCaml in the Menhir grammar to ease MetaOCaml
  maintenance. This is a purely internal change: there is no support
  in the lexer, so no change to the surface OCaml grammar.
  (Oleg Kiselyov, Gabriel Scherer and Florian Angeletti,
   review by Jeremy Yallop)

- #13289: Use C99 for loop to reduce the scope of the for loop iterator.
  (Antonin Décimo, review by Miod Vallat and Gabriel Scherer)

- #13336: compiler-libs, split the `Printtyp` in three to only keep
  "user-friendly" functions in the `Printtyp` module.
  (Florian Angeletti, review by Gabriel Scherer)

- #13361: split runtime/array.c functions to consistently expose
  uniform_array and floatarray versions, use floatarray versions
  in Float.Array.
  (Gabriel Scherer, review by Nicolás Ojeda Bär)

- #13507: A small refactoring to [free_vars] to make it a bit faster
  by not allocating a list when the list is not necessary.
  (Richard Eisenberg, review by Jacques Garrigue)

### Build system:

- #12909: Reorganise how MKEXE_VIA_CC is built to make it correct for MSVC by
  grouping all the linker flags at the end of the C compiler commandline
  (David Allsopp and Samuel Hym, review by Nicolás Ojeda Bär)

- #12992, #13009: Check that flexlink can be executed only when building in a
  native windows environment.
  (Romain Beauxis, review by David Allsopp and Sébastien Hinderer)

- #12996: Only link with -lgcc_eh when available.
  (Romain Beauxis, review by David Allsopp and Miod Vallat)

* #13200: Do not use CFLAGS for linking.
  (Sébastien Hinderer, review by Gabriel Scherer, Antonin Décimo,
  Miod Vallat and Samuel Hym)

- #13201, #13244: Fix and speedup builds with TSan.
  (Sébastien Hinderer, review by Miod Vallat, Gabriel Scherer and
  Olivier Nicole)

* #12578, #12589, #13322, #13519: Use configured CFLAGS and CPPFLAGS *only*
  during the build of the compiler itself. Do not use them when
  compiling third-party C sources through the compiler. Flags for
  compiling third-party C sources can still be specified at configure
  time in the COMPILER_{BYTECODE,NATIVE}_{CFLAGS,CPPFLAGS}
  configuration variables.
  (Sébastien Hinderer, report by William Hu, review by David Allsopp)

- #13285: continue the merge of the sub-makefiles into the root
  Makefile started with #11243, #11248, #11268, #11420, #11675,
  #12198, #12321, #12586, #12616, #12706 and #13048.
  (Sébastien Hinderer, review by David Allsopp and Florian Angeletti)

### Bug fixes:

- #12854: Add a test in the regression suite that flags the bug #12825.
  (Luc Maranget)

- #12888: fix printing of uncaught exceptions in `.cmo` files passed on the
  command-line of the toplevel.
  (Nicolás Ojeda Bär, review by Florian Angeletti, report by Daniel Bünzli)

- #12910, #12920: Fix an unsound interaction between first-class modules
  and polymorphic records by saving and restoring univar_pairs.
  (Stephen Dolan, review by Gabriel Scherer, report by Jeremy Yallop)

- #12994: Remove un-used and unsafe caml_drop_continuation
  (Tim McGilchrist, reviewed by Gabriel Scherer and Miod Vallat)

- #12963: Restore caml_runtime_parameters implementation. This primitive allows
  programs to query the runtime parameters supplied to an OCaml program.
  Implementation missing since OCaml 5.0.
  (Tim McGilchrist, reviewed by David Allsopp and Miod Vallat)

- #13012: parsing: Fix dropped attributes after a '-' or '+'
  The syntax '-(1 [@foo])' was incorrectly parsed as '-1'.
  (Jules Aguillon, reviewed by Gabriel Scherer, report by Gabriel Scherer)

* #13070: On Windows, when configured with bootstrapped flexdll, don't add
  +flexdll to the search path when -nostdlib is specified (which then means
  -L <path-to-flexdll> no longer gets passed to the system linker).
  (David Allsopp, review by Florian Angeletti)

- #13089: Fix bug in `runtime_events` library which could result in garbled
  output under Windows.
  (B. Szilvasy, review by Nicolás Ojeda Bär and Miod Vallat)

- #13088: A few type-checker behaviors look at a type to see if there are
  any labeled arguments in it. This sometimes required expansion, which
  could, in obscure scenarios, result in superfluous type errors.
  (Richard Eisenberg, review by Gabriel Scherer and Jacques Garrigue)

- #13103: FreeBSD/amd64: properly annotate .o files with non-executable stack
  notes (Konstantin Belousov, review by Nicolás Ojeda Bär)

- #13150: improve a transitive-closure computation algorithm in the flambda
  middle-end to avoid a compilation time blowup on Menhir-generated code
  (Florian Weimer, review by Gabriel Scherer and Pierre Chambart,
   report by Richard Jones)

- #13166: Fix a MinGW/MSVC Sys.rename regression on renaming a parent directory
  to an empty child directory.
  (Jan Midtgaard, review by Antonin Décimo, Sébastien Hinderer, and
   David Allsopp)

- #13185, #13192: Reject type-level module aliases on functor parameter
  inside signatures.
  (Jacques Garrigue, report by Richard Eisenberg, review by Florian Angeletti)

- #13170: Fix a bug that would result in some floating alerts `[@@@alert ...]`
  incorrectly triggering Warning 53.
  (Nicolás Ojeda Bär, review by Chris Casinghino and Florian Angeletti)

- #13203: Do not issue warning 53 if the compiler is stopping before attributes
  have been accurately marked.
  (Chris Casinghino, review by Florian Angeletti)

- #13207: Be sure to reload the register caching the exception handler in
  caml_c_call and caml_c_call_stack_args, as its value may have been changed
  if the OCaml stack is expanded during a callback.
  (Miod Vallat, report by Vesa Karvonen, review by Gabriel Scherer and
   Xavier Leroy)

- #13209: Fix configure test that checks whether `ar` supports `@FILE`
  arguments.
  (Nicolás Ojeda Bär, report by Boris D.)

- #13221: Compute more accurate instruction sizes for branch relocation on
  POWER.
  (Miod Vallat, review by Gabriel Scherer)

- #13252: Rework register assignment in the interpreter code on m68k on Linux,
  due to the %a5 register being used by Glibc.
  (Miod Vallat, report by Stéphane Glondu, review by Gabriel Scherer and
   Xavier Leroy)

- #13247: Disable lib_unix/kill test for MacOS AMD64 with TSan, linking
  to llvm bug report causing infinite signal loops.
  (Tim McGilchrist, review by Olivier Nicole, Miod Vallat, Sébastien Hinderer
  and Gabriel Scherer)

- #13234, #13267: Open runtime events file in read-write mode on armel
  (armv5) systems due to atomic operations limitations on that
  platform.
  (Stéphane Glondu, review by Miod Vallat and Vincent Laviron)

- #13273: Fix a call to test in configure.ac that was causing errors when
  LDFLAGS contains several words.
  (Stéphane Glondu, review by Miod Vallat)

- #13290: Fix uninitialized and out of bounds reads in runtime_events_consumer.c
  (Edwin Török, review by Miod Vallat and Antonin Décimo)

- #13306: An algorithm in the type-checker that checks two types for equality
  could sometimes, in theory, return the wrong answer. This patch fixes the
  oversight. No known program triggers the bug.
  (Richard Eisenberg, review by Florian Angeletti)

- #13400: Initialize th->signal_stack to avoid free of uninitialized data
  if the user calls caml_c_thread_unregister on the main thread.
  (Richard W.M. Jones, review by Guillaume Munch-Maccagnoni and
  Gabriel Scherer)

- #13140: POWER back-end: fix issue with call to `caml_call_realloc_stack`
  from a DLL
  (Xavier Leroy, review by Miod Vallat)

- #13263, #13560: fix printing true and false in toplevel and error
  messages (no more unexpected \#true)
  (Florian Angeletti, report by Samuel Vivien, review by Gabriel Scherer)

- #13388, #13540: raises an error message (and not an internal compiler error)
  when two local substitutions are incompatible (for instance `module type
  S:=sig end type t:=(module S)`)
  (Florian Angeletti, report by Nailen Matschke, review by Gabriel Scherer, and
  Leo White)

- #13408: Fix misplaced debug runtime assertion triggerable by a race
  between domain exit and backup thread
  (Miod Vallat and Gabriel Scherer, report by Jan Midtgaard)

- #13417: `Filename.quote_command`: fix handling of forward slashes in program
  path under Win32.
  (Nicolás Ojeda Bär, review by David Allsopp and Damien Doligez)

- #13501: Regression on mutually recursive types caused by #12180.
  Resuscitate Typedecl.update_type.
  (Jacques Garrigue and Takafumi Saikawa, review by Florian Angeletti, Richard
  Eisenberg and Gabriel Scherer)

- #13502: Fix misindexing related to `Gc.finalise_last` that could prevent
  finalisers from being run.
  (Nick Roberts, review by Mark Shinwell)

- #13495, #13514: Fix typechecker crash while typing objects
  (Jacques Garrigue, report by Nicolás Ojeda Bär, review by
   Nicolás Ojeda Bär, Gabriel Scherer, Stephen Dolan, Florian Angeletti)

- #13391, #13551: fix a printing bug with `-dsource` when using
  raw literal inside a locally abstract type constraint
  (i.e. `let f: type \#for. ... `)
  (Florian Angeletti, report by Nick Roberts, review by Richard Eisenberg)

- #13520: Fix compilation of native-code version of systhreads. Bytecode fields
  were being included in the thread descriptors.
  (David Allsopp, review by Sébastien Hinderer and Miod Vallat)

- #13541, #13591: Fix headers for C++ inclusion.
  (Antonin Décimo, review by Nick Barnes, report by Kate Deplaix)

- #13579, #13583: Unsoundness involving non-injective types + gadts
  (Jacques Garrigue, report by @v-gb,
   review by Richard Eisenberg and Florian Angeletti)

- #13598: Falsely triggered warning 56 [unreachable-case]
  This was caused by unproper protection of the retyping function.
  (Jacques Garrigue, report by Tõivo Leedjärv, review by Florian Angeletti)

- #13603, #13604: fix source printing in the presence of the escaped raw
  identifier `\#mod`.
  (Florian Angeletti, report by Chris Casinghino, review by Gabriel Scherer)

OCaml 5.2.0 (13 May 2024)
-------------------------

(Changes that can break existing programs are marked with a "*")

### Restored and new backends:

- #12276, #12601: native-code compilation for POWER (64 bits, little-endian)
  (Xavier Leroy, review by KC Sivaramakrishnan, Anil Madhavapeddy,
   and Stephen Dolan)

- #12667: extend the latter to POWER 64 bits, big-endian, ELFv2 ABI
  (A. Wilcox, review by Xavier Leroy)

### Language features:

- #12295, #12568: Give `while true' a polymorphic type, similarly to
  `assert false'
  (Jeremy Yallop, review by Nicolás Ojeda Bär and Gabriel Scherer,
  suggestion by Rodolphe Lepigre and John Whitington)

- #12315: Use type annotations from arguments in let rec
  (Stephen Dolan, review by Gabriel Scherer)

- #11252, RFC 27: Support raw identifier syntax \#foo
  (Stephen Dolan, review by David Allsopp, Gabriel Scherer and Olivier Nicole)

- #12044: Add local module open syntax for types.
  ```
    module A = struct
      type t = int
      type r = unit
      type s = string
    end

    type example = A.(t * r * s)
  ```
  (Alistair O'Brien, review by Gabriel Scherer, Nicolás Ojeda Bär
   and Florian Angeletti)

- #12456: Document the incompatibility between effects on the one
  hand, and `caml_callback` and asynchronous callbacks (signal
  handlers, finalisers, memprof callbacks...) on the other hand.
  (Guillaume Munch-Maccagnoni, review by KC Sivaramakrishnan)

- #12375: allow use of [@untagged] for all immediate types like char, bool,
  and variant with only constant constructors.
  (Christophe Raffalli, review by Gabriel Scherer)

* #12502: the compiler now normalizes the newline sequence \r\n to
  a single \n character during lexing, to guarantee that the semantics
  of newlines in string literals is not modified by Windows tools
  transforming \n into \r\n in source files.
  Warning 29 [eol-in-string] is not emitted anymore, as the normalization
  gives a more robust semantics to newlines in string literals.
  (Gabriel Scherer and Damien Doligez, review by Daniel Bünzli, David
   Allsopp, Andreas Rossberg, Xavier Leroy, report by Andreas Rossberg)

- #13130: minor fixes to pprintast for raw identifiers and local module open
  syntax for types.
  (Chet Murthy, review by Gabriel Scherer)

### Type system:

- #12313, #11799: Do not re-build as-pattern type when a ground type annotation
  is given. This allows to work around problems with GADTs in as-patterns.
  (Jacques Garrigue, report by Leo White, review by Gabriel Scherer)

### Runtime system:

- #12193: Re-introduce GC compaction for shared pools
  Adds a parallel compactor for the shared pools (which contain major heap
  blocks sized less than 128 words). Explicit only for now, on calls to
  `Gc.compact`.
  (Sadiq Jaffer, Nick Barnes, review by Anil Madhavapeddy, Damien Doligez,
   David Allsopp, Miod Vallat, Artem Pianykh, Stephen Dolan, Mark Shinwell
   and KC Sivaramakrishnan)

- #12850: Update Gc.quick_stat data at the end of major cycles and compaction
  This PR adds an additional caml_collect_gc_stats_sample_stw to the major heap
  cycling stw. This means that Gc.quick_stat now actually reflects the state of
  the heap after a major cycle or compaction.
  (Sadiq Jaffer, review by Miod Vallat and Gabriel Scherer)

- #12859: Ensure Gc.compact does a full major before the compactor runs
  (Sadiq Jaffer, review by Leo White, Mark Shinwell, Gabriel Scherer,
   Josh Berdine, David Allsopp and KC Sivaramakrishnan)

- #10111: Increase the detail of location information for debugging events to
  allow the end line number and character offset to be reported.
  (David Allsopp, review by Nick Barnes, Enguerrand Decorne and Stephen Dolan)

- #10403, #12202: introduce `caml_ext_table_add_noexc` that does not
  raise `Out_of_memory` exceptions and use it inside the blocking sections
  of `caml_read_directory`.  Also, check for overflows in ext table sizes.
  (Xavier Leroy, report by Arseniy Alekseyev, review by Gabriel Scherer)

- #11332, #12702: make sure `Bool_val(v)` has type `bool` in C++
  (Xavier Leroy, report by ygrek, review by Gabriel Scherer)

- #12772, #12787: Avoid using _Bool in public headers for the sake of C++
  compatibility
  (Guillaume Munch-Maccagnoni, report by KC Sivaramakrishnan, review
  by Xavier Leroy and KC Sivaramakrishnan)

- #12223: Constify constructors and flags tables in C code. Now these
  tables will go in the readonly segment, where they belong.
  (Antonin Décimo, review by Gabriel Scherer and Xavier Leroy)

- #12234: make instrumented time calculation more thread-safe on macOS.
  (Anil Madhavapeddy, review by Daniel Bünzli and Xavier Leroy)

- #12235, #12468: introduce and use the `CAMLnoret` macro as
  a lighter alternative to `CAMLnoreturn_start` / `CAMLnoreturn_end`.
  Implement it so as to conform with C11, C23, C++11, C++17.
  (Xavier Leroy and Dhruv Maroo, with help from Antonin Décimo, review by
   Gabriel Scherer and David Allsopp)

- #12275: caml/stack.h: more abstract macros to describe OCaml stacks and
  how to traverse them, supporting more stack layouts.
  (Xavier Leroy, review by KC Sivaramakrishnan and Fabrice Buoro)

- #12268: deliver `Out_of_memory` exception if domain creation fails
  due to memory resource exhaustion.  It was previous always a `Failure`.
  (Anil Madhavapeddy, review by David Allsopp)

- #12300, #12314: Discard out_channel buffered data on permanent I/O error
  (Xavier Leroy, report by Török Edwin, review by Anil Madhavapeddy
  and Nicolás Ojeda Bär)

- #11386: Simplifications and fixes to multicore systhreads implementation.
  (Guillaume Munch-Maccagnoni, review by Anil Madhavapeddy and KC
   Sivaramakrishnan)

- #12875, #12879, #12882: Execute preemptive systhread switching as a
  delayed pending action. This ensures that one can reason within the
  FFI that no mutation happens on the same domain when allocating on
  the OCaml heap from C, consistently with OCaml 4. This also fixes
  further bugs with the multicore systhreads implementation.
  (Guillaume Munch-Maccagnoni, bug reports and suggestion by Mark
   Shinwell, review by Nick Barnes and Stephen Dolan)

- #12408: `Domain.spawn` no longer leaks its functional argument for
  the whole duration of the children domain lifetime.
  (Guillaume Munch-Maccagnoni, review by Gabriel Scherer)

- #12409: Fix unsafety and deadlocks should an asynchronous exception
  arise at specific locations during domain creation and shutdown.
  (Guillaume Munch-Maccagnoni, review by Gabriel Scherer)

- #12114: Add ThreadSanitizer support
  (Fabrice Buoro and Olivier Nicole, based on an initial work by Anmol Sahoo,
   review by Damien Doligez, Sébastien Hinderer, Jacques-Henri Jourdan, Luc
   Maranget, Guillaume Munch-Maccagnoni, Gabriel Scherer)

- #11911, #12381: Restore statmemprof functionality in part, with
  some API changes in Gc.Memprof.
  (Nick Barnes, review by Jacques-Henri Jourdan
   and Guillaume Munch-Maccagnoni).

- #12430: Simplify dynamic bytecode loading in Meta.reify_bytecode
  (Stephen Dolan, review by Sébastien Hinderer, Vincent Laviron and Xavier
   Leroy)

- #12489: Fix an error-handling bug in caml_alloc_sprintf
  (Stephen Dolan, report by Chris Casinghino, review by Jeremy Yallop
   and Xavier Leroy)

- #11307: Finish adapting the implementation of asynchronous actions for
  multicore: soundness, liveness, and performance issues.
  Do not crash if a signal handler is called from an unregistered C
  thread, and other possible soundness issues. Prevent issues where join
  on other domains could make the toplevel unresponsible to Ctrl-C. Avoid
  needless repeated polling in C code when callbacks cannot run
  immediately.
  (Guillaume Munch-Maccagnoni, review by Enguerrand Decorne, Xavier
  Leroy, and KC Sivaramakrishnan)

- #12634: Simplify TSan backtrace bookkeeping upon raise
  (Olivier Nicole and Fabrice Buoro, review by Gabriel Scherer)

* #12686: Some primitives had the wrong types to be callable from the bytecode
  interpreter.  Either fix their types, mark them as `CAMLexport` instead of
  `CAMLprim`, or remove them entirely if no longer used.
  (Xavier Leroy, review by David Allsopp)

- #12700, continuing #11763 and trying to address #12660:
  Use the correct types for primitives when generating the table of primitives
  used by ocamlrun.
  (Xavier Leroy, motivation, review and improvements by Antonin Décimo)

- #12345, #12710: Fix issues with finaliser orphaning at domain termination
  (KC Sivaramakrishnan, report by Gabriel Scherer, review by Gabriel Scherer,
  Sadiq Jaffer and Fabrice Buoro)

- #12599: Refactor Dynlink startup to avoid parsing bytecode sections twice
  (Stephen Dolan, review by David Allsopp, Hugo Heuzard, Damien Doligez and
   Xavier Leroy)

- #12678, #12898: free channel buffers on close rather than on finalization
  (Damien Doligez, review by Jan Midtgaard and Gabriel Scherer, report
   by Jan Midtgaard)

- #12681: Fix TSan false positives due to volatile write handling
  (Olivier Nicole, Fabrice Buoro and Anmol Sahoo, review by Luc Maranget,
   Gabriel Scherer, Hernan Ponce de Leon and Xavier Leroy)

- #12743: Use pthread_sigmask instead of sigprocmask
  Updates usage of sigprocmask to pthread_sigmask in otherlibs/unix.
  (Max Slater, review by Miod Vallat and Xavier Leroy)

- #12769: Unify MSVC and MinGW-w64 code paths, by always using WinAPI
  directly.
  (David Allsopp, Antonin Décimo, and Samuel Hym, review by Nicolás Ojeda Bär)

- #11911, #12382, #12383: Restore statmemprof functionality in part
  (backtrace buffers, per-thread and per-domain data structures,
  GC/allocation interface). (Nick Barnes, review by Gabriel Scherer,
  Fabrice Buoro, Sadiq Jaffer, Guillaume Munch-Maccagnoni, and
  Jacques-Henri Jourdan).

- #12735: Store both ends of the stack chain in continuations
  (Leo White, review by Miod Vallat and KC Sivaramakrishnan)

- #12746: Simplify and clean up TSan annotations
  (Olivier Nicole, review by Miod Vallat and Fabrice Buoro)

- #12809: Add ThreadSanitizer support to FreeBSD/amd64
  (Miod Vallat, review by Gabriel Scherer)

- #12810: Port ThreadSanitizer support to Linux and macOS on arm64
  (Miod Vallat, review by Tim McGilchrist)

- #12811: Define and use the CAMLthread_local macro for TLS variables.
  (Antonin Décimo and Samuel Hym, review by Miod Vallat and Xavier Leroy)

- #12814: More detailed failure messages from `input_value` and `Marshal.from_*`
  (Xavier Leroy, review by Stephen Dolan and Anil Madhavapeddy)

- #12815: Correctly format multi-line locations in exception backtraces, in the
  style that the compiler driver uses.
  (David Allsopp, review by Gabriel Scherer)

- #12773, #12830, #12834: Rewrite `caml_c_thread_(un)register` to fix
  various bugs.
  (Guillaume Munch-Maccagnoni, reported by Miod Vallat, suggested by
   Hari Hara Naveen S, reviewed by Fabrice Buoro, Gabriel Scherer and
   Miod Vallat)

- #12876: Port ThreadSanitizer support to Linux on POWER
  (Miod Vallat, review by Tim McGilchrist)

- #12886: Reinitialize IO mutexes after fork
  (Max Slater, review by Guillaume Munch-Maccagnoni and Xavier Leroy)

- #12907: Port ThreadSanitizer support to Linux on RiscV
  (Miod Vallat, review by Nicolás Ojeda Bär and Fabrice Buoro)

- #12915: Port ThreadSanitizer support to Linux on s390x
  (Miod Vallat, review by Tim McGilchrist)

- #12934: Fix data races between marking and sweeping functions
  (Olivier Nicole, suggested by Stephen Dolan, review by Gabriel Scherer,
   Miod Vallat and Damien Doligez)

### Code generation and optimizations:

- #11239: on x86-64 and RISC-V, reduce alignment of OCaml stacks from 16 to 8.
  This reduces stack usage.  It's only C stacks that require 16-alignment.
  (Xavier Leroy, review by Gabriel Scherer and Stephen Dolan)

- #12311: on POWER, 32-bit FP numbers stored in memory (e.g. in bigarrays)
  were not correctly rounded sometimes.
  (Xavier Leroy, review by Anil Madhavapeddy and Tim McGilchrist)

- #12551, #12608, #12782, #12596: Overhaul of recursive value compilation.
  Non-function recursive bindings are now forbidden from Lambda onwards,
  and compiled using a new Value_rec_compiler module.
  (Vincent Laviron and Lunia Ayanides, review by Gabriel Scherer,
   Stefan Muenzel and Nathanaëlle Courant)

- #1809, #12181: rewrite `compare x y op 0` to `x op y` when values are integers
  (Xavier Clerc, Stefan Muenzel, review by Gabriel Scherer and Vincent Laviron)

- #12825: disable common subexpression elimination for atomic loads... again.
  (Gabriel Scherer, review by KC Sivaramakrishnan, Xavier Leroy
   and Vincent Laviron, report by Vesa Karvonen)

### Standard library:

- #12716: Add `Format.pp_print_nothing` function.
  (Léo Andrès, review by Gabriel Scherer and Nicolás Ojeda Bär)

- #11563: Add the Dynarray module to the stdlib. Dynamic arrays are
  arrays whose length can be changed by adding or removing elements at
  the end, similar to 'vectors' in C++ or Rust.
  (Gabriel Scherer, Simon Cruanes and Florian Angeletti, review by
   Daniel Bünzli, Guillaume Munch-Maccagnoni, Clément Allain,
   Damien Doligez, Wiktor Kuchta and Pieter Goetschalckx)

* #6732, #12423: Make Buffer.add_substitute surjective and fix its
  documentation.
  (Damien Doligez, review by Antonin Décimo)

* #10775, #12499: Half-precision floating-point elements in Bigarray.
  (Anton Yabchinskiy, review by Xavier Leroy and Nicolás Ojeda Bär)

- #11517, #12477: Expose pp_infinity in interface of the format module, and
  check that margin is less than pp_infinity when setting or checking geometry.
  (Janith Petangoda, reported by Simmo Saan, reviewed by Florian Angeletti,
  Simmo Saan, Josh Berdine and Gabriel Scherer)

- #12217: Add `Array.shuffle`.
  (Daniel Bünzli, review by Nicolás Ojeda Bär, David Allsopp and Alain Frisch)

- #12212: Add cache-aligned constructor for atomics. The patch ensures that
  all allocations (of the right size) in the shared heap are aligned.
  (Bartosz Modelski with Gabriel Scherer, Guillaume Munch-Maccagnoni,
   Xavier Leroy, review by Alain Frisch, Anil Madhavapeddy, Gabriel Scherer,
   Guillaume Munch-Maccagnoni, KC Sivaramakrishnan, Stefan Muenzel,
   Xavier Leroy)

- #12307: Add BLAKE2b hashing and an MD5 submodule to the Digest module.
  (Xavier Leroy, review by Olivier Nicole, Gabriel Scherer, Wiktor Kuchta,
   Daniel Bünzli, David Allsopp)

- #12365: Add In_channel.input_bigarray, In_channel.really_input_bigarray,
  Out_channel.output_bigarray, Unix.read_bigarray, Unix.write_bigarray,
  Unix.single_write_bigarray.
  (Nicolás Ojeda Bär, review by Jeremy Yallop, Xavier Leroy, Gabriel Scherer,
   David Allsopp)

- #12455: Add `Array.init_matrix`, `Float.Array.make_matrix`,
  `Float.Array.init_matrix`.
  (Glen Mével, review by Xavier Leroy, Gabriel Scherer, Jeremy Yallop,
  Nicolas Ojeda Bar)

* #12455: `Array.make_matrix dimx dimy f` now raises `Invalid_argument`
  when `dimx = 0 && dimy < 0` This was already specified but not enforced.
  (Glen Mével, report by Jeremy Yallop, review by Nicolás Ojeda Bär)

- #12459: Add `Random.int_in_range`, `Random.int32_in_range`,
  `Random.int64_in_range`, `Random.nativeint_in_range`,
  and their counterpart in `Random.State`.
  (Glen Mével and Xavier Leroy, review by Gabriel Scherer, Xavier Leroy,
   Florian Angeletti)

- #12459: `Random`: restore compatibility between 32-bit integers (JavaScript)
  and 63-bit integers (64-bit OCaml).
  For `Random.full_int` this was guaranteed in 4.14 but wrongly removed in 5.0.
  (Xavier Leroy, review by Glen Mével)

- #12511: Minor performance improvements and cleanups in the implementation
  of modules Int32, Int64, and Nativeint
  (Xavier Leroy, review by Gabriel Scherer and Daniel Bünzli)

- #12558: Adapt GC alarms for multicore and fix their documentation.
  (Guillaume Munch-Maccagnoni, review by KC Sivaramakrishnan
   and Gabriel Scherer)

- #12625: Remove the Closure module from Obj
  (Vincent Laviron, review by Xavier Leroy)

- #12758, #12998: Remove the `Marshal.Compression` flag to the
  `Marshal.to_*` functions.  The compilers are still able to use
  ZSTD compression for compilation artefacts.
  This is a forward port and clean-up of the emergency fix that was introduced
  in OCaml 5.1.1 by #12734.
  (Xavier Leroy, review by Damien Doligez)

- #12784: Fix computation of minor-heap allocation in Gc.counters()
  and Gc.allocated_bytes(). (Nick Barnes, review by Gabriel Scherer)

- #12770: Add `Fun.compose`.
  (Justin Frank, review by Nicolás Ojeda Bär, Daniel Bünzli and Jeremy Yallop)

- #12845: Add `{In,Out}_channel.is_binary_mode` as the dual of
  `set_binary_mode`. This function was previously only available in the internal
  C API.
  (David Allsopp, review by Nicolás Ojeda Bär and Xavier Leroy)

### Other libraries:

- #12213: Dynlink library, improve legibility of error messages
  (Samuel Hym, review by Gabriel Scherer and Nicolás Ojeda Bär)

* #12686: Runtime_events library, C API: define
  `caml_runtime_events_{start,pause,resume}` as returning `void`
  instead of `value`.
  (Xavier Leroy, review by David Allsopp)

### Tools:

- #12340: testsuite: collect known issues with current -short-paths
  implementation for existential types
  (Florian Angeletti, Samuel Hym, review by Florian Angeletti and Thomas Refis)

- #12147: ocamllex: Allow carriage returns at the end of line directives.
  (SeungCheol Jung, review by Nicolás Ojeda Bär)

- #12260: Fix invalid_argument on some external or module aliases in ocamlnat
  (Fabian Hemmer, review by Vincent Laviron)

- #12185: New script language for ocamltest.
  (Damien Doligez with Florian Angeletti, Sébastien Hinderer, Gabriel Scherer,
   review by Sébastien Hinderer and Gabriel Scherer)

- #12371: ocamltest: fix recursive expansion of variables.
  (Antonin Décimo, Damien Doligez, review by Sébastien Hinderer,
   Damien Doligez, Gabriel Scherer, and Xavier Leroy)

* #12497, #12613: Make ocamlc/ocamlopt fail with an error when no
  input files are specified to build an executable.
  (Antonin Décimo, review by Sébastien Hinderer)

- #12576: ocamldep: various refactors.
  (Antonin Décimo, review by Florian Angeletti, Gabriel Scherer, and Léo Andrès)

- #12615: ocamldoc: get rid of the odoc_literate and odoc_todo generators.
  (Sébastien Hinderer, review by Gabriel Scherer and Florian Angeletti)

- #12624: Use $XDG_CONFIG_DIRS in addition to $XDG_CONFIG_HOME when searching
  for init.ml and use this to extend init.ml support to the toplevel when
  running on Windows.
  (David Allsopp, report by Jonah Beckford, review by Nicolás Ojeda Bär and
   Antonin Décimo)

- #12688: Setting the env variable `NO_COLOR` with an empty value no longer
  has effects. Previously, setting `NO_COLOR` with any value, including
  the empty value, would disable colors (unless `OCAML_COLOR` is also set).
  After this change, the user must set `NO_COLOR` with an non-empty value
  to disable colors. This reflects a specification clarification/change
  from the upstream website at https://no-color.org.
  (Favonia, review by Gabriel Scherer)

- #12744: ocamltest: run tests in recursive subdirs more eagerly
  (Nick Roberts, review by Nicolás Ojeda Bär)

- #12901, 12908: ocamllex: add overflow checks to prevent generating incorrect
  lexers; use unsigned numbers in the table encoding when possible.
  (Vincent Laviron, report by Edwin Török, review by Xavier Leroy)

### Manual and documentation:

- #12338: clarification of the documentation of process related function in
  the unix module regarding the first element of args and shell's pid.
  (Christophe Raffalli, review by Florian Angeletti)

- #12473: Document in runtime/memory.c our current understanding of
  accesses to the OCaml heap from the C runtime code -- the problem
  of hybrid programs mixing two memory models.
  (Gabriel Scherer and Guillaume Munch-Maccagnoni, review by Olivier
   Nicole and Xavier Leroy)

- #12694: Document in runtime/tsan.c the TSan instrumentation choices and the
  consequences with regard to the memory model.
  (Olivier Nicole, review by Miod Vallat, Gabriel Scherer, Guillaume
   Munch-Maccagnoni and Fabrice Buoro)

- #12802: Add manual chapter about ThreadSanitizer support
  (Olivier Nicole, review by Miod Vallat, Sebastien Hinderer, Fabrice Buoro,
   Gabriel Scherer and KC Sivaramakrishnan)

- #12819: Clarify which runtime interactions are allowed in custom ops
  (Basile Clément, review by Guillaume Munch-Maccagnoni and Xavier Leroy)

- #12840: manual: update runtime tracing chapter for custom events (ex #12335)
  (Lucas Pluvinage, Sadiq Jaffer and Olivier Nicole, review by Gabriel Scherer,
   David Allsopp, Tim McGilchrist and Thomas Leonard)

- #13066, update OCAMLRUNPARAM documentation for the stack size parameter l
  (Florian Angeletti, review by Nicolás Ojeda Bär, Tim McGilchrist, and
   Miod Vallat)

- #13078: update Format tutorial on structural boxes to mention alignment
  questions.
  (Edwin Török, review by Florian Angeletti)

- #13092: document the existence of the `[@@poll error]` built-in attribute
  (Florian Angeletti, review by Gabriel Scherer)

### Compiler user-interface and warnings:

* #10613, #12405: Simplify the values used for the system variable (`system:` in
  `ocamlopt -config` or the `Config.system` constant). In particular, s390x and
  ppc64 now report "linux" instead of "elf"; all variants of 32-bit ARM on Linux
  now report "linux"; OpenBSD now reports "openbsd" instead of "bsd" for 32-bit
  ARM; FreeBSD, NetBSD and OpenBSD now report the same value for both x86_64 and
  x86_32; x86_32 systems matching *bsd but not freebsd*, netbsd* or openbsd*
  are no longer identified (as on x86_64); x86_32 Linux now reports "linux"
  instead of "linux_elf".
  (David Allsopp, request by Kate Deplaix, review by Sébastien Hinderer and
  Xavier Leroy)

- #11989, #12246, RFC 31: New flag, -H, to allow for transitive dependencies
  without including them in the initial environment.
  (Chris Casinghino, François Bobot, and Gabriel Scherer, review by Leo White
   and Stefan Muenzel, RFC by François Bobot)

- #12247: configure: --disable-ocamldebug can now be used instead
  of --disable-debugger (which remains available for compatibility)
  (Gabriel Scherer, review by Damien Doligez and Sébastien Hinderer)

- #12199: improve the error message for non-overriding `inherit!`
  (Florian Angeletti, review by Jules Aguillon)

- #12210: uniform style for inline code in compiler messages
  (Florian Angeletti, review by Gabriel Scherer)

* #12278, #:12325: Remove the OCAML_FLEXLINK environment variable from the
  compiler drivers. This environment variable was previously used as part of the
  FlexDLL bootstrap procedure and existed solely for that purpose. Its removal
  greatly simplifies both the build system and testsuite machinery.
  (David Allsopp, review by Sébastien Hinderer)

- #12347: error messages: always report missing polyvariant tags
  (Florian Angeletti, report by Tianbo Hao, review by Gabriel Scherer)

- #12224, specialized error message when trying to apply non-functor
  module (e.g `module M = Int(Int)`)
  (Florian Angeletti, review by Gabriel Scherer)

- #12451: Warning 53 (misplaced attributes) now works for all attributes.
  (Chris Casinghino, review by Florian Angeletti)

- #12622: Give hints about existential types appearing in error messages
  (Leo White, review by Gabriel Scherer and Florian Angeletti)

- #12671: When a class type parameter or class parameter does not match,
  identify which parameter in the error message, instead of saying
  "A type parameter" or "A parameter".
  (Stefan Muenzel, review by Gabriel Scherer)

- #12679: Add more detail to the error message and manual in case of
  invalid module type substitutions.
  (Stefan Muenzel, review by Gabriel Scherer and Florian Angeletti)

- #12750: Display the command executed to extract primitives in
  `ocamlc -verbose`.
  (David Allsopp, review by Nicolás Ojeda Bär)

- #12777: Add details about the actual and expected method types to the method
  mismatch error messages.
  (Javier Chávarri, review by Gabriel Scherer and Florian Angeletti)

* #12942: Fix an line ordering in some module inclusion error messages
  (Nick Roberts, review by Florian Angeletti, report by Carl Eastlund)

### Internal/compiler-libs changes:

- #12639: parsing: Attach a location to the RHS of Ptyp_alias
  and improve the 'alias type mismatch' error message.
  (Jules Aguillon, review by Florian Angeletti)

- #12447: Remove 32-bit targets from X86_proc.system
  (Masanori Ogino, review by David Allsopp)

- #12216, #12248: Prevent reordering of atomic loads during instruction
  scheduling.  This is for reference, as instruction scheduling is currently
  unused in OCaml 5.
  (Xavier Leroy, report by Luc Maranget and KC Sivaramakrishnan,
   review by Nicolás Ojeda Bär)

- #12025: Split Typecore.unify_pat_types into two
  to avoid unnecessary references to the environment in type_pat
  (Jacques Garrigue and Takafumi Saikawa, review by Gabriel Scherer)

- #12031: Use dedicated types to represent names of compilation units
  and predefined exceptions in CMO files.
  (Sébastien Hinderer, review by Florian Angeletti, Thomas Refis,
  Gabriel Scherer, Vincent Laviron, Pierre Chambart, Luke Maurer,
  Hugo Heuzard, Xavier Leroy and Damien Doligez)

- #12109: Pack parameters to unification in unification_environment
  (Takafumi Saikawa and Jacques Garrigue, review by Richard Eisenberg)

- #12331, #12361: Pack the unification data for pattern checking in Typecore
  (Takafumi Saikawa and Jacques Garrigue,
   review by Gabriel Scherer, Thomas Refis and Florian Angeletti)

- #12229: Remove global mutable state for typechecking patterns
  in Typecore in favor of local mutable state.
  (Nick Roberts, review by Takafumi Saikawa)

- #12236, #12386, #12391, #12496, #12673: Use syntax as sole determiner of arity
  This changes function arity to be based solely on the source program's
  parsetree. Previously, the heuristic for arity had more subtle heuristics
  that involved type information about patterns.  Function arity is important
  because it determines when a pattern match's effects run and is an input
  into the fast path for function application.

  This change affects tooling: it changes the function constructs in parsetree
  and typedtree.

  See https://github.com/ocaml/RFCs/pull/32 for the original RFC.

  (Nick Roberts; review by Richard Eisenberg, Leo White, and Gabriel Scherer;
  RFC by Stephen Dolan)

- #12542: Minor bugfix to #12236: restore dropped call to `instance`
  (Nick Roberts, review by Jacques Garrigue)

- #12242: Move the computation of stack frame parameters to a separate
  `Stackframe` module, and save the parameters in the results of the
  `Linearize` pass
  (Xavier Leroy, review by KC Sivaramakrishnan and Mark Shinwell)

- #12442: document jump summaries in the pattern-matching compiler
  (Gabriel Scherer and Thomas Refis, review by Florian Angeletti
   and Vincent Laviron)

- #12446, #12792: remove the hooks machinery around channel locking
  in runtime/io.c
  (Gabriel Scherer, review by Xavier Leroy)

- #12389, #12544, #12984, #12987: centralize the handling of metadata for
  compilation units and artifacts in preparation for better unicode support for
  OCaml source files.
  (Florian Angeletti, review by Vincent Laviron and Gabriel Scherer)

- #12532, #12553: improve readability of the pattern-matching debug output
  (Gabriel Scherer, review by Thomas Refis)

- #12537: Use C11/C++11 standard static assertion.
  (Antonin Décimo, review by Sebastien Hinderer, Xavier Leroy,
   and KC Sivaramakrishnan)

- #12169: runtime: document and enforce naming conventions around STW sections.
  (Gabriel Scherer, review by Enguerrand Decorne, Miod Vallat, B. Szilvasy
   and Nick Barnes, report by KC Sivaramakrishnan)

- #12669 : Clean up some global state handling in schedgen
  (Stefan Muenzel, review by Miod Vallat and Gabriel Scherer)

- #12640: Make the module separator used in symbol names configurable
  (Miod Vallat, review by Hugo Heuzard and Xavier Leroy)

- #12691 : Clean up Ctype.expand_abbrev_gen and
  rename Env.add_local_type to add_local_constraint
  (Takafumi Saikawa and Jacques Garrigue, review by Florian Angeletti)

- #12786 : Clean up the algorithm of Ctype.limited_generalize
  (Takafumi Saikawa and Jacques Garrigue, review by Gabriel Scherer)

- #10691: Ast_mapper, Ast_iterator: add functions directive_argument,
  toplevel_directive and toplevel_phrase.
  (Guillaume Petiot, review by Gabriel Scherer and Kate Deplaix)

- #12764: Move all installable headers in `caml/` sub-directories.
  (Antonin Décimo, review by Gabriel Scherer and David Allsopp)

- #12508 : Add compiler-side support for project-wide occurrences in Merlin, by
  generating index tables of all identifier occurrences. This extra data in .cmt
  files is only added when the new flag -bin-annot-occurrences is passed.
  (Ulysse Gérard, Nathanaëlle Courant, suggestions by Gabriel Scherer and Thomas
  Refis, review by Florian Angeletti, Gabriel Scherer and Thomas Refis)

- #12914: Slightly change the s390x assembly dialect in order to build with
  Clang's integrated assembler.
  (Miod Vallat, review by Gabriel Scherer)

- #13001: do not read_back entire shapes to get aliases' uids when building the
  usages index
  (Ulysse Gérard, review by Gabriel Scherer and Nathanaëlle Courant)

### Build system:

- #12198, #12321, #12586, #12616, #12706, #13048: continue the merge of the
  sub-makefiles into the root Makefile started with #11243, #11248,
  #11268, #11420 and #11675.
  (Sébastien Hinderer, review by David Allsopp and Florian Angeletti)

- #12569, #12570: remove 'otherlibraries' as a prerequisite for 'runtop';
  use 'runtop-with-otherlibs' to use a library from otherlibs/
  (Gabriel Scherer, review by Sébastien Hinderer, suggestion by David Allsopp)

- #12652: Make magic numbers easier to bump and duplicate.
  (Sébastien Hinderer, review by Antonin Décimo, David Allsopp and Florian
  Angeletti)

* #12751: --with-target-bindir configure option implemented. This option
  refers to the location of the runtime binaries on the target system for a
  cross-compiler and is embedded in executables produced by ocamlc. It does
  not affect the bytecode executables installed as part of the build. The old
  mechanism `make TARGET_BINDIR=..` no longer works.
  (David Allsopp, review by Damien Doligez, Xavier Leroy and Olivier Nicole)

- #12768, #13030: Detect mingw-w64 coupling with GCC or LLVM, detect clang-cl,
  and fix C compiler feature detection on macOS.
  (Antonin Décimo, review by Miod Vallat and Sébastien Hinderer)

### Bug fixes:

- #10652, #12720: fix evaluation order in presence of optional arguments
  (Jacques Garrigue, report by Leo White, review by Vincent Laviron)

- #12595, #12597: fix a race in `caml_clear_gc_stats_sample`
  (Gabriel Scherer, review by B. Szilvasy, report by B. Szilvasy)

- #12580: Fix location of alias pattern variables.
  (Chris Casinghino, review Gabriel Scherer, report by Milo Davis)

- #12583: Add a closing event for when `EV_MAJOR_EPHE_MARK` is complete
  (Sudha Parimala, review by Gabriel Scherer)

- #12566: caml_output_value_to_malloc wrongly uses `caml_stat_alloc`
  instead of `malloc` since 4.06, breaking (in pooled mode) user code
  that uses `free` on the result. Symmetrically,
  caml_input_value_from_malloc should use `free`.
  (Gabriel Scherer, review by Xavier Leroy and Enguerrand Decorne,
   report by Ido Yariv)

- #12490: Unix: protect the popen_processes hashtable with a mutex
  (Gabriel Scherer, report by Olivier Nicole, review by Xavier Leroy)

- #11931: Fix tricky typing bug with type substitutions
  (Stephen Dolan, review by Leo White and Jacques Garrigue)

- #12037, #12171: Fix get_extern_state potential NULL dereference.
  (Alexander Skvortsov, report by Török Edwin,
   design by Gabriel Scherer, Xavier Leroy)

- #12635: Fix get_intern_state potential NULL dereference.
  (Antonin Décimo, review by KC Sivaramakrishnan)

- #12032, #12059: Bug fixes related to compilation of recursive definitions
  (Vincent Laviron, report by Victoire Noizet, review by Gabriel Scherer)

* #12145: Loopy constraints cause ocamlc to loop.
  Fixed by completely removing the call to `update_type` in
  `Typedecl.transl_type_decl`, as the expansion is already checked by
  `check_regularity`. As a result, recursion is more polymorphic,
  which may cause some (essentially wrong) type declarations to have
  unbound type variables, and some constraints unrelated to the concrete
  type to be ignored (see tests/typing-misc/constraints.ml).
  (Jacques Garrigue, report by Richard Eisenberg, review by Leo White)

- #12207, #12222: Make closure computation linear in the number of recursive
  functions instead of quadratic
  (Vincent Laviron, report by François Pottier, review by Nathanaëlle Courant
  and Gabriel Scherer)

- #11040, #12591: fix a data race in major_gc.c
  (Gabriel Scherer, review by Guillaume Munch-Maccagnoni
   and KC Sivaramakrishnan, report by Sadiq Jaffer)

- #12238, #12403, #12698: read input files in one go to avoid source reprinting
  issues.
  (Gabriel Scherer, report by Mike Spivey and Vincent Laviron, review by
   Nicolás Ojeda Bär, Xavier Leroy and Jeremy Yallop)

- #12334, #12368: Bad error message with mutually recursive abbreviations
  (Jacques Garrigue, report by Richard Eisenberg, review by Gabriel Scherer
   and Richard Eisenberg)

- #12401: `seek_in` and `seek_out` sometimes returned normally when given
  negative offsets, instead of failing. Now both functions should consistently
  raise `Sys_error` in this case.
  (Nicolás Ojeda Bär, review by Gabriel Scherer)

- #12267: Fix stack alignment computation
  (Miod Vallat, report by Jan Midtgaard, review by Gabriel Scherer)

- #12395, #12404: Fix thread-unsafety in the fallback implementation of
  `Unix.create_process` (the one used when `posix_spawnp` is unavailable)
  (Xavier Leroy, report by Chris Vine, review by Nicolás Ojeda Bär)

- #12949: open shadowing mistriggers
  (Gabriel Scherer, review by Florian Angeletti, report by Andreas Rossberg)

- #12526: Honor `ocaml.inline always` attribute on functions with
  optional arguments and default values in the Closure backend
  (Alain Frisch, review by Vincent Laviron)

- #12677, #12889: make Domain.DLS thread-safe
  (Gabriel Scherer, review by Olivier Nicole and Damien Doligez,
   report by Vesa Karvonen)

- #12561: Fix crash when combining TSan and frame-pointers
  (Fabrice Buoro and Olivier Nicole, report by Jan Midtgaard, review by Miod
  Vallat and Gabriel Scherer)

- #12482: Rework bounds checking code in the POWER backend
  (Miod Vallat and Xavier Leroy, report by Jan Midtgaard, review by
   KC Sivaramakrishnan)

- #12528, #12703: Avoid pointer arithmetic overflow in Tag_val macro
  (very likely harmless, but can trigger alarms)
  (Xavier Leroy, report by Sam Goldman, review by Guillaume Munch-Maccagnoni)

- #12593: TSan should handle Effect.Unhandled correctly
  (Fabrice Buoro and Olivier Nicole, report by Jan Midtgaard and Miod Vallat,
   review by Gabriel Scherer)

- #12684: fix locations filename in AST produced by the `-pp` option
  (Gabriel Scherer, review by Florian Angeletti)

- #12714: check whether macros are defined before using them to ensure
  that the headers can always be used in code which turns on -Wundef
  (or equivalent).
  (Antonin Décimo, review by Miod Vallat, Gabriel Scherer,
   Xavier Leroy, and David Allsopp)

- #12726: fix segmentation fault under Windows when executing a bytecode file if
  the runtime (`ocamlrun.exe`) cannot be found.
  (Vadim Zborovskii, Nicolás Ojeda Bär, report by Vadim Zborovskii, review by
  David Allsopp)

- #12727, #12730: fix bug with value let-rec and labelled applications
  (Vincent Laviron, review by Gabriel Scherer)

* #12751: Always keep within the 128 character limit for shebang lines. Previous
  fix in #8622 handled building the compiler with a long prefix; this patch
  extends this to the bytecode executables emitted by that compiler.
  (David Allsopp, review by Damien Doligez, Xavier Leroy and Olivier Nicole)

- #12755: Fix data race on global pools arrays of pool_freelist
  (Fabrice Buoro and Olivier Nicole, review by Gabriel Scherer)

- #12796, #12801: Fix memory corruption in caml_unix_alloc_sockaddr
  (Thomas Leonard, review by Nicolás Ojeda Bär)

- #12737: Fix data races in minor_gc.c and caml_natdynlink_open
  (Olivier Nicole, review by Stefan Muenzel, Miod Vallat, Guillaume
   Munch-Maccagnoni, Gabriel Scherer and Xavier Leroy)

- #12831: Fix call to caml_call_realloc_stack for s390x in PIC mode
  (Vincent Laviron, report by Jerry James, review by Miod Vallat)

* #12837: Show non-generalizable type parameters in type definitions
  Changes type of type parameters in outcometree.mli.
  (Jacques Garrigue, review by Richard Eisenberg)

- #12897: fix locking bugs in Runtime_events
  (Gabriel Scherer and Thomas Leonard,
   review by Olivier Nicole, Vincent Laviron and Damien Doligez,
   report by Thomas Leonard)

- #12851: Fix race between runtime events teardown and event emission
  (Olivier Nicole, review by Miod Vallat and Gabriel Scherer)

- #12860: Fix an assertion that wasn't taking into account the possibility of an
  ephemeron pointing at static data.
  (Mark Shinwell, review by Gabriel Scherer and KC Sivaramakrishnan)

- #12861: Fix a possible crash in the `threads` library.
  (Mark Shinwell, review by Gabriel Scherer and KC Sivaramakrishnan)

- #11040, #12894: Silence false data race observed between caml_shared_try_alloc
  and oldify. Introduces macros to call tsan annotations which help annotate
  a ``happens before'' relationship.
  (Hari Hara Naveen S and Olivier Nicole,
   review by Gabriel Scherer and Miod Vallat)

- #12958: Fix tail-modulo-cons compilation of try-with, && and ||
  expressions.
  (Gabriel Scherer and Nicolás Ojeda Bär, report by Sylvain Boilard, review by
  Gabriel Scherer)

- #12919: Fix register corruption in caml_callback2_asm on s390x.
  (Miod Vallat, review by Gabriel Scherer)

- #12924, #12930: Rework package constraint checking to improve interaction with
  immediacy
  (Chris Casinghino and Florian Angeletti, review by Florian Angeletti and
   Richard Eisenberg)

- #12969: Fix a data race in caml_darken_cont
  (Fabrice Buoro and Olivier Nicole, review by Gabriel Scherer and Miod Vallat)

- #12971, #12974: fix an uncaught Ctype.Escape exception on some
  invalid programs forming recursive types.
  (Gabriel Scherer, review by Florian Angeletti, report by Neven Villani)

- #13019: Remove linking instructions for the Unix library from threads.cma
  (this was done for threads.cmxa in OCaml 3.11). Eliminates warnings from
  new lld when using threads.cma of duplicated libraries.
  (David Allsopp, review by Nicolás Ojeda Bär)

- #13058: Add TSan instrumentation to caml_call_gc(), since it may raise
  exceptions.
  (Fabrice Buoro, Olivier Nicole, Gabriel Scherer and Miod Vallat)

- #13079: Save and restore frame pointer across Iextcall on ARM64
  (Tim McGilchrist, review by KC Sivaramakrishnan and Miod Vallat)

- #13094: Fix undefined behavior of left-shifting a negative number.
  (Antonin Décimo, review by Miod Vallat and Nicolás Ojeda Bär)

OCaml 5.1.1 (8 December 2023)
----------------------------

### Standard library:

* #12562, #12734, #12783: Remove the `Marshal.Compression` flag to the
  `Marshal.to_*` functions introduced in 5.1 by #12006, as it cannot
  be implemented without risking to link -lzstd with all
  ocamlopt-generated executables.  The compilers are still able to use
  ZSTD compression for compilation artefacts.
  (Xavier Leroy and David Allsopp, report by Kate Deplaix, review by
   Nicolás Ojeda Bär, Kate Deplaix, and Damien Doligez).

### Bug fixes:

- #11800, #12707: fix an assertion race condition in `install_backup_thread`
  (Jan Midtgaard, review by Gabriel Scherer)

- #12318: GC: simplify the meaning of custom_minor_max_size: blocks with
  out-of-heap memory above this limit are now allocated directly in
  the major heap.
  (Damien Doligez, report by Stephen Dolan, review by Gabriel Scherer)

- #12439: Finalize and collect dead custom blocks during minor collection
  (Damien Doligez, review by Xavier Leroy, Gabriel Scherer and KC
  Sivaramakrishnan)

- #12486, #12535: Fix delivery of unhandled effect exceptions on amd64 with
  --enable-frame-pointers
  (Miod Vallat, report by Jan Midtgaard, review by Gabriel Scherer)

- #12581, #12609: Fix error on uses of packed modules outside their pack
  to correctly handle nested packs
  (Vincent Laviron, report by Javier Chávarri, review by Pierre Chambart)

- #12590, #12595: Move `caml_collect_gc_stats_sample` in
  `caml_empty_minor_heap_promote` before barrier arrival.
  (B. Szilvasy, review by Gabriel Scherer)

- #12623, fix the computation of variance composition
  (Florian Angeletti, report by Vesa Karvonen, review by Gabriel Scherer)

- #12645, #12649 fix error messages for cyclic type definitions in presence of
  the `-short-paths` flag.
  (Florian Angeletti, report by Vesa Karvonen, review by Gabriel Scherer)

- #12712, #12742: fix an assertion boundary case in `caml_reset_young_limit`
  (Jan Midtgaard, review by Guillaume Munch-Maccagnoni and KC Sivaramakrishnan)

- #12713, #12715: disable common subexpression elimination for atomic loads
  (Gabriel Scherer and Vincent Laviron,
   review by Vincent Laviron, KC Sivaramakrishnan and Xavier Leroy,
   report by Vesa Karvonen and Carine Morel)

- #12757: Fix ocamlnat (native toplevel) by registering frametables correctly
  (Stephen Dolan, Nick Barnes and Mark Shinwell,
   review by Vincent Laviron and Sébastien Hinderer)

- #12791: `extern` is applied to definitions of `caml_builtin_cprim`
  and `caml_names_of_builtin_cprim` when linking bytecode '-custom'
  executables with a C++ linker.
  (Shayne Fletcher, review by Antonin Décimo and Xavier Leroy)

- #12491, #12493, #12500, #12754: Do not change GC pace when creating
  sub-arrays of bigarrays
  (Xavier Leroy, report by Ido Yariv, analysis by Gabriel Scherer,
   review by Gabriel Scherer and Fabrice Buoro)

OCaml 5.1.0 (14 September 2023)
-------------------------------

### Restored backends

- #11418, #11708: RISC-V multicore support.
  (Nicolás Ojeda Bär, review by KC Sivaramakrishnan)

- #11712, #12258, #12261: s390x / IBM Z multicore support:
  OCaml & C stack separation; dynamic stack size checks; fiber and
  effects support.
  (Aleksei Nikiforov, with help from Vincent Laviron and Xavier Leroy,
   additional suggestions by Luc Maranget,
   review by the same and KC Sivaramakrishnan)

- #11642: Restore Cygwin port. Add GC messages for address space reservations
  when OCAMLRUNPARAM option v includes 0x1000.
  (David Allsopp, review by Xavier Leroy, Guillaume Munch-Maccagnoni
  and Gabriel Scherer)

### Standard library:

- #12006, #12064: Add `Marshal.Compression` flag to `Marshal.to_*` functions.
  When this flag is explicitly set, marshaled data is compressed using ZSTD.
  On some practical examples, the marshalled output became three times smaller
  at no noticeable cost on the marshalling time.
  (Xavier Leroy, review by Edwin Török and Gabriel Scherer, fix by Damien
   Doligez)

- #10464: Add List.is_empty.
  (Craig Ferguson, review by David Allsopp)

- #11848: Add `List.find_mapi`,
  `List.find_index: ('a -> bool) -> 'a list -> int option`,
  `Seq.find_mapi`, `Seq.find_index`, `Array.find_mapi`, `Array.find_index`,
  `Float.Array.find_opt`, `Float.Array.find_index`, `Float.Array.find_map`,
  `Float.Array.find_mapi`.
  (T. Kinsart, review by Daniel Bünzli and Nicolás Ojeda Bär)

- #11410: Add Set.to_list, Map.to_list, Map.of_list,
  `Map.add_to_list: key -> 'a -> 'a list t -> 'a list t`.
  (Daniel Bünzli, review by Nicolás Ojeda Bär and Gabriel Scherer)

- #11836, #11837: Add `Array.map_inplace`, `Array.mapi_inplace`,
  `Float.Array.mapi_inplace` and `Float.Array.mapi_inplace`.
  (Léo Andrès, review by Gabriel Scherer, KC Sivaramakrishnan and
  Nicolás Ojeda Bär)

- #10967: Add Filename.temp_dir.
  (David Turner, review by Anil Madhavapeddy, Valentin Gatien-Baron, Nicolás
  Ojeda Bär, Gabriel Scherer, and Daniel Bünzli)

- #11246: Add "hash" and "seeded_hash" functions to Bool, Int, Char, Float,
  Int32, Int64, and Nativeint.
  (Nicolás Ojeda Bär, review by Xavier Leroy and Gabriel Scherer)

- #11488: Add `Mutex.protect: Mutex.t -> (unit -> 'a) -> 'a`
  for resource-safe critical sections protected by a mutex.
  (Simon Cruanes, review by Gabriel Scherer, Xavier Leroy,
   Guillaume Munch-Maccagnoni)

- #11581: Add type equality witness
    `type (_, _) eq = Equal: ('a, 'a) eq`
  in a new module Stdlib.Type.
  (Nicolás Ojeda Bär, review by Daniel Bünzli, Jacques Garrigue, Florian
  Angeletti, Alain Frisch, Gabriel Scherer, Jeremy Yallop and Xavier Leroy)

- #11843: Add `In_channel.input_lines` and `In_channel.fold_lines`.
  (Xavier Leroy, review by Nicolás Ojeda Bär and Wiktor Kuchta).

- #11856, #11859: Using TRMC, the following `Stdlib` functions are now
  tail-recursive:
    Stdlib.(@), List.append,
    List.concat_map.
  (Jeremy Yallop, review by Daniel Bünzli, Anil Madhavapeddy, Nicolás Ojeda Bär,
   Gabriel Scherer, and Bannerets)

- #11362, #11402: Using TRMC, the following `Stdlib` functions are now
  tail-recursive:
    List.map, List.mapi, List.map2,
    List.filter, List.filteri, List.filter_map,
    List.init,
    List.of_seq.
  (Nicolás Ojeda Bär, review by Xavier Leroy and Gabriel Scherer)


- #11878, #11965: Prevent seek_in from marking buffer data as valid after
  closing the channel. This could lead to inputting uninitialized bytes.
  (Samuel Hym, review by Xavier Leroy and Olivier Nicole)

- #11128: Add In_channel.isatty, Out_channel.isatty.
  (Nicolás Ojeda Bär, review by Gabriel Scherer and Florian Angeletti)

- #10859: Add `Format.pp_print_iter` and `Format.pp_print_array`.
  (Léo Andrès and Daniel Bünzli, review by David Allsopp and Hugo Heuzard)

- #10789: Add `Stack.drop`
  (Léo Andrès, review by Gabriel Scherer)

* #10899: Change Stdlib.nan from signaling NaN to quiet NaN.
  (Greta Yorsh, review by Xavier Leroy, Guillaume Melquiond and
  Gabriel Scherer)

- #11026, #11667, #11858: Rename the type of the accumulator
  of fold functions to 'acc:
  fold_left : ('acc -> 'a -> 'acc) -> 'acc -> 'a list -> 'acc
  fold_right : ('a -> 'acc -> 'acc) -> 'a list -> 'acc -> 'acc
  fold_left_map : ('acc -> 'a -> 'acc * 'b) -> 'acc -> 'a list -> 'acc * 'b list
  ...
  (Valentin Gatien-Baron and François Berenger,
  review by Gabriel Scherer and Nicolás Ojeda Bär)

- #11354: Hashtbl.find_all is now tail-recursive.
  (Fermín Reig, review by Gabriel Scherer)

- #11500: Make Hashtbl.mem non-allocating.
  (Simmo Saan, review by Nicolás Ojeda Bär)

- #11412: Add Sys.is_regular_file
  (Xavier Leroy, review by Anil Madhavapeddy, Nicolás Ojeda Bär, David Allsopp)

- #11322, #11329: serialization functions Random.State.{of,to}_binary_string
  between Random.State.t and string
  (Gabriel Scherer, report by Yotam Barnoy,
   review by Daniel Bünzli, Damien Doligez, Hugo Heuzard and Xavier Leroy)

- #11830: Add Type.Id with
  `val provably_equal : 'a Type.Id.t -> 'b Type.Id.t -> ('a, 'b) Type.eq option`
  (Daniel Bünzli, review by Jeremy Yallop, Gabriel Scherer, Wiktor Kuchta,
   Nicolás Ojeda Bär)

- #12184, #12320: Sys.rename Windows fixes on directory corner cases.
  (Jan Midtgaard, review by Anil Madhavapeddy)

* #11565: Enable -strict-formats by default. Some incorrect format
  specifications (for `printf`) where silently ignored and now fail.
  Those new failures occur at compile-time, except if you use advanced
  format features like `%(...%)` that parse format strings dynamically.
  Pass -no-strict-formats to revert to the previous lenient behavior.
  (Nicolás Ojeda Bär, review by David Allsopp)

### Installation size

  Specific efforts have been made during this release to reduce the filesystem
size of installed artifacts of the compiler distribution.
The installation size of 5.1 is 272 MiB compared to 521 MiB for 5.0.
Some of those changes will benefit all OCaml packages.

- ocaml/RFCs#23, #12006: use compressed marshaled format from #12006 for .cmi,
  .cmt, .cmti files, and for debug info in .cmo and .cma files, resulting in
  major reduction in size.
  (Xavier Leroy, review by Edwin Török and Gabriel Scherer,
   RFC by Simon Cruanes)

- #11981: Reduce size of OCaml installations by removing debugging information
  from installed bytecode executables.  It is no longer possible to
  run ocamldebug over these installed bytecode executables, nor to get
  exception backtraces for them.
  (Xavier Leroy, review by David Allsopp, report by Fabrice Le Fessant)

* #11993: install only bytecode executables for the `ocamlmklib`, `ocamlcmt`,
  `ocamlprof`, `ocamlcp`, `ocamloptp`, and `ocamlmktop` tools, but no
  native-code executables.  A tool like `ocamlmklib` for example is now
  installed directly to `$BINDIR/ocamlmklib`; `ocamlmklib.byte` and
  `ocamlmklib.opt` are no longer installed to `$BINDIR`.
  (Xavier Leroy, review by Gabriel Scherer)

### Runtime system:

- #11589, #11903: Modify the GC pacing code to make sure the GC keeps
   up with allocations in the presence of idle domains.
   (Damien Doligez and Stephen Dolan, report by Florian Angeletti,
   review by KC Sivaramakrishnan and Sadiq Jaffer)

- #11743: Speed up weak array operations
  (KC Sivaramakrishnan, review by François Bobot and Sadiq Jaffer)

- #12131: Simplify implementation of weak hash sets, fixing a
  performance regression. (Nick Barnes, review by François Bobot,
  Alain Frisch and Damien Doligez).

- #11474, #11998, #12065: Add support for user-defined events in the runtime
  event tracing system.
  (Lucas Pluvinage, review by Sadiq Jaffer, Guillaume Munch-Maccagnoni,
   Enguerrand Decorne, Gabriel Scherer and Anil Madhavapeddy)

- #11827, #12249: Restore prefetching for GC marking
  (Fabrice Buoro and Stephen Dolan, review by Gabriel Scherer and Sadiq Jaffer)

- #11144: Restore frame-pointers support for amd64
  (Fabrice Buoro, review by Frédéric Bour and KC Sivaramakrishnan)

- #11935: Load frametables of dynlink'd modules in batch
  (Stephen Dolan, review by David Allsopp and Guillaume Munch-Maccagnoni)

- #11284, #12525: Use compression of entries scheme when pruning mark stack.
  Can decrease memory usage for some workloads, otherwise should be
  unobservable.
  (Tom Kelly, review by Sabine Schmaltz, Sadiq Jaffer and Damien Doligez)

* #11865, #11868, #11876: Clarify that the operations of a custom
  block must never access the OCaml runtime. The previous
  documentation only mentioned the main illicit usages. In particular,
  since OCaml 5.0, it is no longer safe to call
  `caml_remove_global_root` or `caml_remove_generational_global_root`
  from within the C finalizer of a custom block, or within the
  finalization function passed to `caml_alloc_final`. As a workaround,
  such a finalization operation can be registered with `Gc.finalize`
  instead, which guarantees to run the finalizer at a safe point.
  (Report by Timothy Bourke, discussion by Yotam Barnoy, Timothy
  Bourke, Sadiq Jaffer, Xavier Leroy, Guillaume Munch-Maccagnoni, and
  Gabriel Scherer)

- #12130: Fix multicore crashes with weak hash sets. Fixes #11934.
  (Nick Barnes, review by François Bobot)

- #12099: Add ocamlrund option, -events, to produce a trace of
  debug events during bytecode interpretation. Fixes #12098.
  (Richard L Ford, review by Gabriel Scherer)

- #12001: Fix book keeping for last finalisers during the minor cycle
  (KC Sivaramakrishnan and Enguerrand Decorne, report by Guillaume Bury
   and Vincent Laviron, review by Sadiq Jaffer and KC Sivaramakrishnan)

- #11919: New runtime events counters for major heap stats and minor heap
  resizing.
  (Sadiq Jaffer, review by Gabriel Scherer and David Allsopp)

- #11287, #11872, #11955: Clean up reserved header bits (once used for
  Spacetime profiling).
  (Nick Barnes, review by Gabriel Scherer and Damien Doligez)

- #11750: Decouple major slice from minor GC.
  (KC Sivaramakrishnan, review by Sadiq Jaffer, Guillaume Munch-Maccagnoni and
  Damien Doligez)

- #11796: protect lazy computation of code fragment digest by a mutex.
  This makes the thread sanitizer happier, and avoids duplicating
  the hashing work.
  (Gabriel Scherer, review by Xavier Leroy, report by Olivier Nicole)

- #11137: new `Unsafe_store_tag(val, new_tag)` macro to stop using
  `Tag_val(val)` as lvalue.
  (Gabriel Scherer, review by Xavier Leroy, Guillaume Munch-Maccagnoni
   and Nicolás Ojeda Bär)

- #11880: Restore the correct sigmask in systhreads.
  (Christiano Haesbaert, review by Guillaume Munch-Maccagnoni and
   Sébastien Hinderer)

- #11881: Fix thread-unsafety of registration of operations for "custom"
   values.
  (Guillaume Munch-Maccagnoni, review by Gabriel Scherer and KC
   Sivaramakrishnan)

- #11980: fix quadratic behavior in natdynlink by using a STW section
  for frame-descriptor updates.
  (Gabriel Scherer, review by Sadiq Jaffer, report by André Maroneze
  for Frama-C and Guillaume Melquiond for Coq)

- #12121: unrooted implementations of caml_callback*_exn
  (Gabriel Scherer, review by KC Sivaramakrishnan and Xavier Leroy)

- #3921, #12039, #12128: poll for signals in long-running polymorphic
  comparisons.
  (B. Szilvasy, Gabriel Scherer and Xavier Leroy, review by
   Stefan Muenzel, Guillaume Munch-Maccagnoni and Damien Doligez)

- #12231: Support MinGW-w64 11.0 winpthreads library, where the macro
  to set up to get flexdll working changed
  (David Allsopp and Samuel Hym, light review by Xavier Leroy)

* #12512: Add volatile casts to FFI macros to enforce memory model (technically
  a breaking change although no opam package seemed broken by it.)
  (Olivier Nicole, suggested by Guillaume Munch-Maccagnoni, review by Gabriel
   Scherer and Xavier Leroy)

### Language features:

* #11694: Add short syntax for generative functor types `() -> ...`
  (Jeremy Yallop, review by Gabriel Scherer, Nicolás Ojeda Bär,
  Jacques Garrigue)


* #11457: Remove old polymorphic variant syntax.
  With ``type t = [ `A | `B ]``, one could use the syntax `#t` in types,
  where it means the same thing as `[< t]`, and in patterns, where it means
  ``(`A | `B)``. The use of `#t` in types for polymorphic variants
  was deprecated since 2001, and is now removed. The syntax remains available
  in patterns, or for objects -- when `t` is a class type.
  (Stefan Muenzel, review by Gabriel Scherer and Jacques Garrigue)

* #11984: Add dedicated syntax for generative functor application.
  Previously, OCaml did not distinguish between `F ()` and
  `F (struct end)`, even though the latter looks applicative. Instead,
  the decision between generative and applicative functor application
  was made based on the type of `F`. With this patch, we now distinguish
  these two application forms; writing `F (struct end)` for a generative
  functor leads to new warning 73.
  (Frédéric Bour and Richard Eisenberg, review by Florian Angeletti)


- #9975, #11365: Make empty types (`type t = |`) immediate.
  (Antal Spector-Zabusky, review by Gabriel Scherer)

### Type system:

* #6941, #11187, #12483: prohibit using classes through recursive modules
  inheriting or including a class belonging to a mutually-recursive module
  would previous behave incorrectly, and now results in a clean error.
  (Leo White, review by Gabriel Scherer and Florian Angeletti)

* #12189, #12211: anonymous row variables in explicitly polymorphic type
  annotation, e.g. `'a. [< X of 'a ] -> 'a`, are now implicitly
  universally quantified (in other words, the example above is now read
  as `'a 'r. ([< X of 'a ] as 'r) -> 'a`).
  (Florian Angeletti and Gabriel Scherer, review by Jacques Garrigue)

### Code generation and optimizations:

- #11967: Remove traces of Obj.truncate, which allows some mutable
  loads to become immutable.
  (Nick Barnes, review by Vincent Laviron and KC Sivaramakrishnan)

- #9945, #10883: Turn boolean-result float comparisons into primitive operations
  Uses the architecture's elementary operations for float comparisons,
  when available, rather than branching and then setting the return value.
  (Stefan Muenzel, review by Stephen Dolan, Alain Frisch and Vincent Laviron)

- #8998, #11321, #11430: change mangling of OCaml long identifiers
  from `camlModule__name_NNN` to `camlModule.name_NNN`.  The previous
  mangling schema, using `__`, was ambiguous.
  (Xavier Leroy, report by sliquister and Michael Bacarella,
   review by Gabriel Scherer)

- #10834: The -safer-matching option disables type-based optimizations of
  pattern-matching compilation. This allows to produce a match failure if
  a pattern-matching was wrongly assumed to be exhaustive. Since the
  exhaustiveness check for GADTs has had bugs in the past, it may be
  useful if you need extra security with GADTs.
  (Jacques Garrigue, review by Gabriel Scherer)

- #11102: Speed up register allocation by permanently spilling registers
  (Stephen Dolan, review by Xavier Leroy)

- #11383: Restrict the local function optimisation to forbid moving code
  inside a sub-function
  (Vincent Laviron, review by Gabriel Scherer)

- #11686: Better spilling heuristic for the Linear Scan allocator for more
  efficient stack usage.
  (Nicolás Ojeda Bär, Gabriel Scherer, Alain Frisch, review by Gabriel Scherer,
  Alain Frisch and Nathanaëlle Courant)

- #11904: Remove arm, i386 native-code backends that were already
  disabled at configuration time.
  (Nicolás Ojeda Bär, review by Stephen Dolan, Anil Madhavapeddy, and Xavier
  Leroy)

- #11134: Optimise 'include struct' in more cases
  (Stephen Dolan, review by Leo White and Vincent Laviron)

### Other libraries:

- #11374: Remove pointer cast to a type with stricter alignment requirements
  in Windows implementation of Unix.gettimeofday. Windows implementations of
  caml_unix_map_file, caml_unix_lseek and caml_unix_lseek_64 now release the
  runtime lock. Windows implementation of caml_unix_lockf modernised and
  simplified. Where possible, 64 bit integers are used instead of LARGE_INTEGER
  structs.
  (David Allsopp, review by Jonah Beckford and Xavier Leroy)

- #11475: Make Unix terminal interface bindings domain-safe
  (Olivier Nicole and Xavier Leroy, review by Xavier Leroy)

- #11775: Unix.write on a non-blocking socket under Windows will return normally
  if the write blocks after some data has already been written (as otherwise
  there is no way of knowing how much data has been written before
  blocking). The same behaviour was already present under Unix.
  (Nicolás Ojeda Bär, review by David Allsopp)

* #11991: Unix on Windows: map ERROR_TOO_MANY_LINKS to EMLINK.
  (Nicolás Ojeda Bär)

- #12067: Document Windows specific meanings of `Unix.process_status`
  type
  (Samuel Hym, review by David Allsopp)

- #12072: Document and test that Sys.rename works over directories too
  (Jan Midtgaard, review by Anil Madhavapeddy and Xavier Leroy)

### Tools:

- #11889, #11978: ocamldoc: handle injectivity annotations and wildcards in type
  parameters.
  (Florian Angeletti, report by Wiktor Kuchta, review by Jules Aguillon)

- #11787: Fix GDB scripts to work with OCaml 5's heap layout. (Nick
  Barnes)

- #11772: fix ocamlyacc's handling of raw string literals
  (Demi Marie Obenour)

- #9290: Add a directive to switch off debugging in toplevel.
  This allows to see optimized bytecode with -dlambda.
  (Jacques Garrigue, review by Gabriel Scherer)

- #11166: ocamllex: the union of two character sets "cset1 | cset2" can now be
  used in any context where a character set is expected.
  (Nicolás Ojeda Bär, Martin Jambon, review by Sébastien Hinderer)

- #11718: ocamlyacc: OCaml-style comments are now supported, in addition to
  the C-style comments already supported.  The syntax is the same as that used
  in OCaml code.
  (Demi Marie Obenour, review by Damien Doligez)

- #11728: ocamlyacc: generate line directives for %type declarations
  (Demi Marie Obenour, review by Damien Doligez)

- #11773: ocamlyacc: Do not allow quoted literals (such as 'a' or "bc")
  in a token name or %type declaration.  Previously such literals were
  accepted by ocamlyacc, but produced malformed OCaml that was rejected
  by the compiler.
  (Demi Marie Obenour, review by Gabriel Scherer)

- #11774: ocamlyacc: fail if there is an I/O error
  (Demi Marie Obenour, review by Gabriel Scherer)

- #11973: Add support for postfixed mingw host triplets
  (Romain Beauxis)

- #12165: ocamldoc, use standard doctype to avoid quirk mode.
  (Florian Angeletti, review by Gabriel Scherer)

### Manual and documentation:

- #11476: Add examples in documentation of Hashtbl, Queue, Atomic, Format
  (Simon Cruanes, review by Yotam Barnoy, Gabriel Scherer, Daniel Bünzli,
   Ulugbek Abdullaev, and Nicolás Ojeda Bär)

- #11883, #11884: Update documentation for In_channel and Out_channel
  with examples and sections to group related functions.
  (Kiran Gopinathan, review by Daniel Bünzli and Xavier Leroy)


- #12095, #12097: Put the sample code of the user's manual and reference
  documentation of the standard library under the CC0 1.0 Universal
  (CC0 1.0) Public Domain Dedication license.

- #11892: Document the semantic differences of Unix.exec* between Unix and
  Windows.
  (Boris Yakobowski, review by Daniel Bünzli, Gabriel Scherer and Nicolás Ojeda
  Bär)

- #9430, #11291: Document the general desugaring rules for binding operators.
  (Gabriel Scherer, review by Nicolás Ojeda Bär)

- #11481: Fix the type of Unix.umask to Unix.file_perm -> Unix.file_perm
  (Favonia, review by Sébastien Hinderer)

- #11514: Document ocamltest builtin variables and actions
  (Olivier Nicole, review by Sébastien Hinderer)

- #11676: Fix missing since annotation in the `Sys` and `Format` modules
  (Github user Bukolab99, review by Florian Angeletti)

- #12028: Update format documentation to make it clearer that
  `pp_print_newline` flushes its newline
  (Florian Angeletti, review by Gabriel Scherer)

- #12201: in the tutorial on modules, replace priority queue example by
  a simpler example based on FIFO queues.
  (Xavier Leroy, review by Anil Madhavapeddy and Nicolás Ojeda Bär).

- #12352: Fix a typo in the documentation of Arg.write_arg
  (Christophe Raffalli, review by Florian Angeletti)

- #7179, #11894: correct the description of CAMLreturn and CAMLreturn0 in
  the Interfacing C page and memory.h file.
  (Dong An, review by Guillaume Munch-Maccagnoni and Olivier Nicole )

### Compiler user-interface and warnings:

- #10647: Show hints for the "undefined global" error in the toplevel
  (Wiktor Kuchta, review by Gabriel Scherer)

- #12116: Don't suggest to insert a semicolon when the type is not unit
  (Jules Aguillon, review by Florian Angeletti)

- #11679: Improve the error message about too many arguments to a function
  (Jules Aguillon, review by Gabriel Scherer and Florian Angeletti)

- #10009: Improve the error reported by mismatched struct/sig and =/: in module
  and module type bindings.
  (Jules Aguillon, review by Gabriel Scherer)

- #11530: Include kinds in kind mismatch error message.
  "Error: This variant or record definition does not match that of type M.t
          The original is abstract, but this is a record".
  (Leonhard Markert, review by Gabriel Scherer and Florian Angeletti)

- #11646: Add colors to error message hints.
  (Christiana Anthony, review by Florian Angeletti)

- #11235, #11864: usage warnings for constructors and fields can now be disabled
  on field-by-field or constructor-by-constructor basis
  (Florian Angeletti, review by Gabriel Scherer)

- #11888: Improve the error message when type variables cannot be deduced from
  the type parameters:
  Before:
    "Error: In this definition, a type variable cannot be deduced
            from the type parameters."
  After:
    "Error: In the GADT constructor
              T : 'a -> 'a s t
     the type variable 'a cannot be deduced from the type parameters."
  (Stefan Muenzel, review by Florian Angeletti and Gabriel Scherer)


- #10818: Preserve integer literal formatting in type hint.
  (Leonhard Markert, review by Gabriel Scherer and Florian Angeletti)

- #11338: Turn some partial application warnings into hints.
  (Leo White, review by Stephen Dolan)

- #10931: Improve warning 14 (illegal backslash) with a better explanation
  of the causes and how to fix it.
  (David Allsopp, Florian Angeletti, Lucas De Angelis, Gabriel Scherer,
  review by Nicolás Ojeda Bär, Florian Angeletti, David Allsopp and
  Gabriel Scherer)

- #10911: Improve the location reported by parenthesized assert expressions
  (Fabian Hemmer, review by Gabriel Scherer)

- #1391, #7645, #3922: Add an early error when compiling different
  modules with mismatching -for-pack
  (Pierre Chambart and Vincent Laviron, review by Mark Shinwell)

- #11297: Report "unclosed" error when "done" is missing in a "do .. done"
  construct.
  (Nicolás Ojeda Bär, review by Gabriel Scherer)

- #11635, #5461, #10564: turn warning 31 (Module_linked_twice) into a hard error
  for ocamlc — this was already an error with ocamlopt.
  (Hugo Heuzard, review by Valentin Gatien-Baron and Gabriel Scherer)

- #11653: Add the -no-absname option to ocamlc, ocamlopt and ocamldep.
  (Abiola Abdulsalam, review by Sébastien Hinderer and Florian Angeletti)

- #11696: Add the -no-g option to ocamlc and ocamlopt.
  (Abiola Abdulsalam, review by Sébastien Hinderer, Nicolás Ojeda Bär and
  Florian Angeletti)

- #11722: clearer error messages on non-well-founded type definitions
  (Gabriel Scherer, review by Jacques Garrigue)

- #11819: make the `native_compiler` and `native_dynlink` configuration
  variables available through ocamlc -config.
  (Sébastien Hinderer, review by Gabriel Scherer and David Allsopp)

- #8602, #11863: Add -stop-after lambda flag option
  (Douglas Smith and Dmitrii Kosarev, review by Gabriel Scherer)

- #11910: Simplify naming convention for shadowed or ephemeral identifiers in
  error messages (eg: `Illegal shadowing of included type t/2 by t`)
  (Florian Angeletti, review by Jules Aguillon)

- #12024: insert a blank line between separate compiler messages
  (Gabriel Scherer, review by Florian Angeletti, report by David Wong)

- #12088, #9265, #11949: ocamldebug: fix confusing repeating behavior
  on blank lines within source scripts
  (Damien Doligez, review by Gabriel Scherer, report by Gaëtan Gilbert)

- #12107: use aliases to mark weak row variables: `_[< ... ]`, `< _..>`, `_#ct`
  are now rendered as `[< ...] as '_weak1`, `< .. > as '_weak1`,
  and `#ct as '_weak1`.
  (Florian Angeletti, suggestion by Stefan Muenzel, review by Gabriel Scherer)

- #12051: Improve the error messages when type variables cannot be generalized
  (Stefan Muenzel, review by Florian Angeletti)

* #12094: Trigger warning 5 (ignored-partial-application) when the scrutinee of
  a pattern matching is of arrow type and all cases match wildcard or exception
  patterns.
  (Nicolás Ojeda Bär, review by Gabriel Scherer)

### Internal/compiler-libs changes:

- #11018, #11869: Clean up Types.Variance, adding a description of
  the lattice used, and defining explicitly composition.
  (Jacques Garrigue, review by Gabriel Scherer and Jeremy Yallop)

- #11536: Introduce wrapper functions for level management
  ([Ctype.with_level], etc) and for type variable scoping
  ([Typetexp.with_local_type_variable_scope]).
  The older API ([Ctype.(begin_def,end_def)], [Typetexp.(narrow,widen)], etc.)
  is now removed.
  (Jacques Garrigue and Takafumi Saikawa, review by Gabriel Scherer)

- #11601, #11612, #11628, #11613, #11623, #12120 : Clean up some
  global state handling in emitcode, bytepackager, bytegen,
  bytesections, spill.
  (Hugo Heuzard, Stefan Muenzel, review by Vincent Laviron, Gabriel Scherer
   and Nathanaëlle Courant)

- #12119, #12188, #12191: mirror type constraints on value binding in the
  parsetree:
  the constraint `typ` in `let pat : typ = exp` is now directly stored
  in the value binding node in the parsetree.
  (Florian Angeletti, review by  Richard Eisenberg)

- #11912: Refactoring handling of scoped type variables
  (Richard Eisenberg, review by Gabriel Scherer and Florian Angeletti)


- #11691, #11706: use __asm__ instead of asm for strict ISO C conformance
  (Xavier Leroy, report by Gregg Reynolds , review by Sadiq Jaffer)

- #11693: Remove use of C99 Variable Length Arrays (VLAs) in the runtime.
  (David Allsopp, review by Xavier Leroy, Guillaume Munch-Maccagnoni,
   Stefan Muenzel and Gabriel Scherer)

- #12138: Generalise interface for BUILD_PATH_PREFIX_MAP mapping.
  Absolute paths are now rewritten too.
  (Richard L Ford, suggestions and review by Gabriel Scherer)

- #10512: explain the compilation strategy for switches on constructors
  (Gabriel Scherer, review by Vincent Laviron)

- #11990: Improve comments and macros around frame descriptors.
  (Nick Barnes, review by Gabriel Scherer)

- #11847, #11849, #11851, #11898: small refactorings in the type checker
  (Gabriel Scherer, review by Nicolás Ojeda Bär)

- #11027: Separate typing counter-examples from type_pat into retype_pat;
  type_pat is no longer in CPS.
  (Jacques Garrigue and Takafumi Saikawa, review by Gabriel Scherer)

- #11286, #11515: disambiguate identifiers by using how recently they have
  been bound in the current environment
  (Florian Angeletti, review by Gabriel Scherer)

- #11364: Allow `make -C testsuite promote` to take `TEST` and `LIST` variables
  (Antal Spector-Zabusky, review by Gabriel Scherer and David Allsopp)

- #11446: document switch compilation (lambda/switch.ml)
  (Gabriel Scherer, review by Luc Maranget and Vincent Laviron)

- #11568: Encode inline record types in Path.t
  (Leo White and Hyunggyu Jang, review by Gabriel Scherer)

- #11569: Remove hash type encoding
  (Hyunggyu Jang, review by Gabriel Scherer and Florian Angeletti)

- #11627: use return values instead of globals for linear scan intervals
  (Stefan Muenzel, review by Nicolás Ojeda Bär)

- #11634: Dll.open_dll now properly handles opening for execution while already
  opened for checking
  (Hugo Heuzard, review by Nicolás Ojeda Bär)

* #11745, #12358: Debugger and toplevels: embed printer types rather than
  reading their representations from topdirs.cmi at runtime.
  This change also removes the ocamlmktop initialization module introduced
  in #11382 which was no longer useful.
  This change breaks toplevel scripts relying on the visibility of `Topdirs`
  in the initial toplevel environment without loading `topfind`.
  Since the opam default `.ocamlinit` file loads `topfind`, it is expected
  that only scripts run with `ocaml -noinit` are affected.
  For those scripts, accessing `Topdirs` now requires the `compiler-libs`
  directory to be added to the toplevel search path with
  ```
    #directory "+compiler-libs";;
  ````
  as was already the case for the other modules in the toplevel interface
  library.
  (Sébastien Hinderer, review by Florian Angeletti, Nicolás Ojeda Bär and
  Gabriel Scherer)

- #11615: remove global variables form asmcomp/linearize.ml
  (Stefan Muenzel, review by Nicolás Ojeda Bär

- #10856: Add location, attribute(s) visitors to Tast_mapper/Tast_iterator
  (Yan Dong, review by Nicolás Ojeda Bär and Gabriel Scherer)

- #11933: Use the correct machtype when reading the code pointer from closures
  (Nathanaëlle Courant, review by Gabriel Scherer and Vincent Laviron)

- #11972: refactor runtime/frame_descriptors.c
  in preparation for quadratic-time fix
  (Gabriel Scherer, review by Enguerrand Decorne)

- #11997: translate structured constants into their Obj.t representation
  at compile time rather than link time. Changes the way dumpobj prints
  these constants because their representation becomes untyped.
  (Sébastien Hinderer, review by Xavier Leroy, Nicolás Ojeda Bär and
  Hugo Heuzard)

- #12011: remove Ctype.reified_var_counter
  (Takafumi Saikawa and Jacques Garrigue, review by Gabriel Scherer)

- #12012: move calls to Typetexp.TyVarEnv.reset inside with_local_level etc.
  (Jacques Garrigue and Takafumi Saikawa, review by Gabriel Scherer)

- #12034: a logarithmic algorithm to find the next free variable
  (Gabriel Scherer, review by Stefan Muenzel)

- #12092: remove Lev_module_definition from lambda
  (Nick Roberts, review by Gabriel Scherer)

- #12117: Remove arity-interrupting elaboration of module unpacks
  (Nick Roberts, review by Richard Eisenberg and Jacques Garrigue)

- #12118: stop storing names of predefined exceptions in the
  cu_required_globals field of compilation unit descriptors.
  (Sébastien Hinderer, review by Vincent Laviron)

- #12125: Add Misc.print_see_manual and modify [@manual_ref] to accept
  lists for simpler printing of manual references
  (Stefan Muenzel, review by Florian Angeletti)

### Build system:

- #11844: Reduce verbosity of `make` logs by printing program invocations in
  shorthand (eg `OCAMLC foo.cmo`). Setting `V=1` recovers the old style (with
  full command-lines).
  (Xavier Leroy, Nicolás Ojeda Bär, review by Sébastien Hinderer)


- #11243, #11248, #11268, #11420, #11675: merge the sub-makefiles into
  the root Makefile.
  (Sébastien Hinderer, review by David Allsopp and Florian Angeletti)

- #11828: Compile otherlibs/ C stubs in two version for native and bytecode
  (Olivier Nicole, review by Sébastien Hinderer and Xavier Leroy)

- #12265: Stop adding -lexecinfo to cclibs (leftover debugging code from the
  multicore project). Harden the feature probe for -lm in configure so -lm is
  only added if strictly necessary. configure.ac now correctly propagates
  library flags for the Windows ports, allowing Windows OCaml to be configured
  with ZSTD support.
  (David Allsopp, review by Sébastien Hinderer)

### Bug fixes:

- #8813, #12029: In the toplevel, let the user type several phrases in one line
  (Damien Doligez, report by Daniel Bünzli, review by Gabriel Scherer and
   Wiktor Kuchta)

- #12062: fix runtime events consumer: when events are dropped they shouldn't be
  parsed. (Lucas Pluvinage)

- #12132: Fix overcounting of minor collections in GC stats.
  (Damien Doligez, review by Gabriel Scherer)

- #12017: Re-register finaliser only after calling user alarm in Gc.create_alarm
  (Fabrice Buoro, report by Sam Goldman, review by Guillaume Munch-Maccagnoni)

- #11887, #11893: Code duplication in pattern-matching compilation
  (Vincent Laviron, report par Greta Yorsh, review by Luc Maranget and
   Gabriel Scherer)

- #10664, #11600: Unsoundness in the typing of polymorphic methods
  involving polymorphic variants
  (Jacques Garrigue, report by Mike Shulman, review by Gabriel Scherer)

- #11302, #11412: `ocamlc` and `ocamlopt` should not remove generated files
  when they are not regular files.
  (Xavier Leroy, report by Thierry Martinez, review by
   Anil Madhavapeddy, Nicolás Ojeda Bär, David Allsopp)

- #10348, #10560, #11561: Expand GADT equations lazily during unification to
  avoid ambiguity
  (Jacques Garrigue, review by Leo White)

- #11436: Fix wrong stack backtrace for out-of-bound exceptions raised
  by leaf functions.
  (Tom Kelly and Xavier Leroy, review by Mark Shinwell)

- #11450, #12018: Fix erroneous functor error messages that were too eager to
  cast `struct end` functor arguments as unit modules in `F(struct end)`.
  (Florian Angeletti, review by Gabriel Scherer)

- #11643: Add missing test declaration to float_compare test, so that it will
  run.
  (Stefan Muenzel, review by David Allsopp)

- #11630: Use correct location when reporting record labels with non-existent
  paths.
  (Nicolás Ojeda Bär, report by Jason Gross, review by Gabriel Scherer)

- #11727: Ensure push_defaults can push past module patterns, fixing an
  currying optimisation accidentally disabled by #10340.
  (Stephen Dolan, review by Gabriel Scherer)

- #11771: Use a more relaxed mode for unification in Ctype.subst
  (Leo White, review by Jacques Garrigue and Gabriel Scherer)

- #11803, #11808: on x86, the destination of an integer comparison must be
  a register, it cannot be a stack slot.
  (Vincent Laviron, review by Xavier Leroy, report by
   Emilio Jesús Gallego Arias)

- #11809: Protect Parmatch.pats_of_type from missing cmis
  (Jacques Garrigue, review by Stephen Dolan and Gabriel Scherer)

- #11824: Fix a crash when calling `ocamlrun -b`
  (Florian Angeletti, review by Sébastien Hinderer)

- #11815: Marshalling continuations raises invalid argument exception.
  (Jérôme Vouillon, review by Nicolás Ojeda Bär, Stephen Dolan and
   Hugo Heuzard)

- #11846: Mark rbx as destroyed at C call for Win64 (mingw-w64 and Cygwin64).
  Reserve the shadow store for the ABI in the c_stack_link struct instead of
  explicitly when calling C functions. This simultaneously reduces the number of
  stack pointer manipulations and also fixes a bug when calling noalloc
  functions where the shadow store was not being reserved.
  (David Allsopp, report by Vesa Karvonen, review by Xavier Leroy and
   KC Sivaramakrishnan)

- #11850: When stopping before the `emit` phase (using `-stop-after`), an empty
  temporary assembly file is no longer left in the file system.
  (Nicolás Ojeda Bär, review by Gabriel Scherer and Xavier Leroy)

- #11866: Fix the result of `caml_read_directory()` on non-existent paths.
  (Andrei Paskevich and Charlène Gros, review by David Allsopp and
   Nicolás Ojeda Bär)

- #11879: Bugfix for Ctype.nondep_type
  (Stephen Dolan, review by Gabriel Scherer)

- #12004: Don't ignore function attributes on lambdas with locally abstract
  types.
  (Chris Casinghino, review by Gabriel Scherer)

- #12037: Fix some data races by using volatile when necessary
  (Fabrice Buoro and Olivier Nicole, review by Guillaume Munch-Maccagnoni,
  Gabriel Scherer and Luc Maranget)

- #12046: Flush stderr when tracing the parser
  (Hugo Heuzard, review by David Allsopp and Nicolás Ojeda Bär)

- #12061, #12063: don't add inconsistent equalities when computing
  high-level error messages for functor applications and inclusions.
  (Florian Angeletti, review by Gabriel Scherer)

- #12075: auto-detect whether `ar` support @FILE arguments at
  configure-time to avoid using this feature with toolchains
  that do not support it (eg FreeBSD/Darwin).
  (Nicolás Ojeda Bär, review by Xavier Leroy, David Allsopp, Javier
  Chávarri, Anil Madhavapeddy)

- #12103, 12104: fix a concurrency memory-safety bug in Buffer
  (Gabriel Scherer, review by Florian Angeletti, report by Samuel Hym)

- #12112: Fix caml_callback{2,3}_exn when used with effect handlers.
  (Lucas Pluvinage, review by Gabriel Scherer, David Allsopp and Xavier Leroy)

- #12134: Use ghost location for nodes created when handling defaults in
  optional arguments.
  (Paul-Elliot Anglès d'Auriac, review by Gabriel Scherer)

- #12153: Fix segfault in bytecode programs involving recursive value
  definitions of values of size 0
  (Vincent Laviron, Xavier Leroy, Gabriel Scherer,
   review by Xavier Leroy, report by Nick Roberts)

- #12162: Fix miscompilation on amd64 backends involving integer overflows
  (Vincent Laviron and Greta Yorsh, review by Stefan Muenzel)

- #12170: fix pthread_geaffinity_np configure check for android
  (David Allsopp, review by Sébastien Hinderer)

- #12178: Fix runtime events consumer poll function returning an invalid value
  instead of an OCaml integer value. (Lucas Pluvinage)

- #12252: Fix shared library build error on RISC-V.
  (Edwin Török, review by Nicolás Ojeda Bär and Xavier Leroy)

- #12255, #12256: Handle large signal numbers correctly (Nick Barnes,
   review by David Allsopp).

- #12277: ARM64, fix a potential assembler error for very large functions by
  emitting stack reallocation code before the body of the function.
  (Xavier Leroy, review by KC Sivaramakrishnan)

- #12253, #12342: Fix infinite loop in signal handling.
  (Guillaume Munch-Maccagnoni, report by Thomas Leonard, review by
   KC Sivaramakrishnan and Sadiq Jaffer)

- #12445: missing GC root registrations in runtime/io.c
  (Gabriel Scherer, review by Xavier Leroy and Jeremy Yallop)

- #12481, #12505: Fix incorrect initialization of array expressions
  `[|e1;...;eN|]` when `N` is large enough to require major heap allocation.
  (Xavier Leroy, report by Andrey Popp, analysis by KC Sivaramakrishnan
   and Vincent Laviron, review by Gabriel Scherer)

- #11150, #11207, #11936: Avoid recomputation in Typedecl.check_wellfounded
  (Jacques Garrigue, report by Boris Yakobowski, review by Gabriel Scherer)

- #11186, #11188: Fix composition of coercions with aliases
  (Vincent Laviron, report and review by Leo White)

- #12486: Fix delivery of unhandled effect exceptions on s390x
  (Miod Vallat, report by Jan Midtgaard, review by Vincent Laviron and Xavier
  Leroy)

OCaml 5.0.0 (15 December 2022)
------------------------------

- #10831: Multicore OCaml
  (Enguerrand Decorne, Stephen Dolan, Tom Kelly, Sadiq Jaffer,
  Anil Madhavapeddy, Sudha Parimala, KC Sivaramakrishnan,
  Leo White, the Tarides multicore team,
  review by Florian Angeletti, Damien Doligez, Xavier Leroy,
  Guillaume Munch-Maccagnoni, Olivier Nicole, Nicolás Ojeda Bär,
  Gabriel Scherer, the OCaml core development team, and many
  other valued reviewers.)

### Language features:

### Runtime system:

- #11400: Runtime events counters fixes
  Fixes mismatch between OCaml and C APIs, removes events from 4.x that
  are not present in the 5.0 GC and adds some missing probes.
  (Sadiq Jaffer, review by Gabriel Scherer, Florian Angeletti)

- #11368: Runtime events buffer size OCAMLRUNPARAMS fix
  The runtime events buffer size can now be set via the 'e' OCAMLRUNPARAM.
  This is previously mistakenly enabled/disabled tracing instead.
  (Sadiq Jaffer, review by KC Sivaramakrishnan, David Allsopp, Damien Doligez)

- #11308: Add environment variable to preserve runtime_events after exit
  If the environment variable OCAML_RUNTIME_EVENTS_PRESERVE exists then the
  runtime will not remove the runtime events ring buffers at exit. This
  makes tracing very short running programs more reliable.
  (Sadiq Jaffer, review by KC Sivaramakrishnan)

- #10964: Ring-buffer based runtime tracing (runtime_events)
  Runtime_events is a very low overhead runtime tracing system designed for
  continuous monitoring of OCaml applications.
  (Sadiq Jaffer, review by Anil Madhavapeddy, Enguerrand Decorne,
  Richard Warburton, Gabriel Scherer, Sabine Schmaltz, Florian Angeletti,
  Patrick Ferris, Tom Kelly)

* #10723: do not use `-flat-namespace` linking for macOS.
  (Carlo Cabrera, review by Damien Doligez)

* #10863, #10933: Remove support for old, unprefixed C runtime function names
  such as `alloc`.  The new names prefixed with `caml_` must be used instead,
  such as `caml_alloc`.  Consequently, it is no longer needed to define
  `CAML_NAME_SPACE` to avoid bringing unprefixed names into scope: this is now
  the default behavior.
  (Nicolás Ojeda Bär, review by Xavier Leroy)

- #10902: Do not register empty code fragments in natdynlink.
  (David Allsopp, review by Xavier Leroy and Damien Doligez)

- #10965: `caml_fatal_error_hook`, GC timing hooks, and
  `caml_scan_roots_hook` are now atomic variables. Restore GC timing
  hooks in multicore.
  (Guillaume Munch-Maccagnoni, review by Enguerrand Decorne, Xavier
  Leroy, Gabriel Scherer, and KC Sivaramakrishnan)

- #11209: Add a public and thread-safe timing hook running at domain
  termination, after this domain has stopped running any OCaml code:
  `caml_domain_terminated_hook`. This can be useful for implementing
  domain-local state in C.
  (Guillaume Munch-Maccagnoni, review by Xavier Leroy and Gabriel
  Scherer)

- #10875, #11731: Add option to allocate fiber stacks and sigaltstacks with
  mmap(MAP_STACK) instead of malloc. This is exposed via a configure
  --enable-mmap-map-stack option, and is enabled by default on OpenBSD where
  it is mandatory.
  (Anil Madhavapeddy, review by Gabriel Scherer, Tom Kelly,
   Michael Hendricks and KC Sivaramakrishnan).

- #10950: Do not use mmap to allocate Caml_state.
  In order to reduce virtual memory usage, we dynamically allocate
  the domain_state structure.
  (Enguerrand Decorne, KC Sivaramakrishnan and Tom Kelly,
  review by Anil Madhavapeddy and Gabriel Scherer)

- #11010: Use strerror_r for reentrant error string conversion.
  (Anil Madhavapeddy and Xavier Leroy, review by same and Edwin Török)

- #11002, #11066, #11086: Do not use Begin_roots/End_roots macros in
  the runtime system.  Also fix a missing root registration in the
  implementation of Unix.write on Windows.
  (Nicolás Ojeda Bär, Daniel Bünzli and Antonin Décimo,
   review by Xavier Leroy and David Allsopp)

- #11022: Track GC work for all managed bigarray allocations
  (Stephen Dolan, report by Andrew Hunter, review by Damien Doligez)

- #10802: Use 4.12 value macros and helpers in C code
  (Antonin Décimo, review by Gabriel Scherer)

- #11105: Fix handling of fiber stack cache with multiple domains
  (Jon Ludlam, KC Sivaramakrishnan and Tom Kelly)

- #11054: Respect user provided maximum stack space
  Make sure the stack we initially request is sized accordingly to
  the user provided settings. tmc/stack_space is also updated by
  this PR in order to account for this change.
  (Enguerrand Decorne, report by Jon Ludlam,
  review by Tom Kelly, KC Sivaramakrishnan and Gabriel Scherer)

- #11238: Increase the default limit for the stack size to 128 Mi words,
  i.e. 1 Gib for 64-bit platforms and 512 Mib for 32-bit platforms.
  (Xavier Leroy, review by Sébastien Hinderer)

* #11295: An ISO C 2011 compliant compiler, including full support for atomic
  types, is now required to build the OCaml runtime system.
  (Xavier Leroy, review by David Allsopp and Sébastien Hinderer)

- #10915, #11039, #11057, #11095, #11190: Implement quality treatment for
  asynchronous actions in multicore. Reimplement the old behaviour of
  `caml_process_pending*` for multicore.
  (Guillaume Munch-Maccagnoni, review by Sadiq Jaffer and Gabriel Scherer)

- #11303: Ensure that GC is not invoked from bounds check failures
  (Stephen Dolan, review by Sadiq Jaffer and Xavier Leroy)

- #11304: Fix data race on Windows file descriptors
  (Olivier Nicole and Xavier Leroy, review by Xavier Leroy, David Allsopp,
   and Sadiq Jaffer)

* #11337: pass 'flags' metadata to root scanners, to optimize stack
  scanning in the bytecode interpreter.
  Changes the interface of user-provided root-scanning hooks.
  (Gabriel Scherer, review by Xavier Leroy,
   Guillaume Munch-Maccagnoni, Sadiq Jaffer and Tom Kelly)

* #11255: in the C interface, `&Field(v, i)` now has type `volatile value *`
  instead of `value *` in OCaml 4.  This makes the memory model
  for mixed OCaml/C code better defined, but can cause warnings or type
  errors in user C code.
  (KC Sivaramakrishnan, review by Xavier Leroy, Gabriel Scherer and
  Guillaume Munch-Maccagnoni, additional discussions with Stephen
  Dolan and Luc Maranget)

- #5299, #4787, #11138, #11272, #11506: To help debugging, `Caml_state`
  now dynamically checks that the domain lock is held, and fails
  otherwise (with a fatal error at most entry points of the C API, or
  systematically in debug mode). A new variable `Caml_state_opt` is
  introduced, and is `NULL` when the domain lock is not held. This
  allows to test from C code if the current thread holds the lock of
  its domain.
  (Guillaume Munch-Maccagnoni, review by Florian Angeletti, Damien
  Doligez, Sadiq Jaffer, Xavier Leroy, and Gabriel Scherer)

- #11223: The serialization format of custom blocks changed in 4.08,
  but the deserializer would still support the pre-4.08 format.  OCaml
  5.x removed support for this old format; provide a clear error message
  in this case.
  (Hugo Heuzard, review by Gabriel Scherer)

- #11504, #11522: Use static allocation in `caml_make_float_vect` in
  no-flat-float-array mode, it's more efficient and avoids a a race condition
  (Xavier Leroy, report by Guillaume Munch-Maccagnoni, review by David Allsopp)

- #11652: Fix benign off-by-one error in Windows implementation of caml_mem_map.
  (David Allsopp, review by Gabriel Scherer)

- #11669, #11704: Fix construction of Effect.Unhandled exceptions in the
  bytecode interpreter.
  (David Allsopp and Xavier Leroy, report by Samuel Hym, review by Xavier Leroy
  and Gabriel Scherer)

### Code generation and optimizations:

- #10972: ARM64 multicore support: OCaml & C stack separation;
  dynamic stack size checks; fiber and effects support.
  (Tom Kelly and Xavier Leroy, review by KC Sivaramakrishnan, Xavier Leroy,
  Guillaume Munch-Maccagnoni, Eduardo Rafael, Stephen Dolan and
  Gabriel Scherer)

### Standard library:

- #10742: Use LXM as the pseudo-random number generator for module Random.
  Add `Random.State.split` and `Random.split` to "split" a PRNG off
  another PRNG.
  (Xavier Leroy, review by Gabriel Scherer and Hugo Heuzard)

* #10867, #11345: Remove deprecated values: Array.create, Array.make_float,
  Array.create_matrix, Bytes.uppercase, Bytes.lowercase, Bytes.capitalize,
  Bytes.uncapitalize, Char.lowercase, Char.uppercase, Filename.temp_dir_name,
  Int32.format, Int64.format, Nativeint.format, Format.bprintf, Format.kprintf,
  Format.set_all_formatter_output_functions,
  Format.get_all_formatter_output_functions,
  Format.pp_set_all_formatter_output_functions,
  Format.pp_get_all_formatter_output_functions, Format.pp_open_tag,
  Format.pp_close_tag, Format.open_tag, Format.close_tag,
  Format.formatter_tag_functions, Format.pp_set_formatter_tag_functions,
  Format.pp_get_formatter_tag_functions, Format.set_formatter_tag_functions,
  Format.get_formatter_tag_functions, Gc (mutability of the fields of type
  Gc.control), Lazy.lazy_from_fun, Lazy.lazy_from_val, Lazy.lazy_is_val,
  Obj.set_tag, Obj.truncate, Obj.final_tag, Obj.extension_constructor,
  Obj.extension_name, Obj.extension_id, Scanf.stdib, Scanf.fscanf,
  Scanf.kfscanf, Stdlib.( & ), Stdlib.( or ), String.set, String.copy,
  String.fill, String.unsafe_set, String.unsafe_fill, String.uppercase,
  String.lowercase, String.capitalize, String.uncapitalize, Thread.kill,
  Thread.wait_write, Thread.wait_read, the whole ThreadUnix module, the
  infix operator (.[]<-).
  (Nicolás Ojeda Bär, review by Damien Doligez)

* #10896: Remove Stream, Genlex and Pervasives. Also remove legacy standalone
  bigarray library (the Bigarray module is now part of the standard library).
  (Nicolás Ojeda Bär, review by Kate Deplaix and Anil Madhavapeddy)

- #10921: Use getentropy, when available, to seed the generator during
  `Random.self_init`
  (Michael Hendricks, review by Gabriel Scherer, Xavier Leroy, and
  Anil Madhavapeddy)

* #10924: Add deprecated attribute to Printexc.catch, Printf.kprintf and
  Unix.SO_ERROR.
  (Nicolás Ojeda Bär, review by Damien Doligez)

- #10986: Add Scanf.sscanf_opt, Scanf.bscanf_opt and Scanf.scanf_opt.
  (Nicolás Ojeda Bär, review by Florian Angeletti and Gabriel Scherer)

* #11157: Rename "hash" in the "Hashtbl.SeededHashedType" signature to
  "seeded_hash". This allows defining both seeded and unseeded hash functions in
  the same module.
  (Nicolás Ojeda Bär, review by Gabriel Scherer and Xavier Leroy)

- #8878: Add String.hash and String.seeded_hash.
  (Tom Kelly, review by Alain Frisch and Nicolás Ojeda Bär)

- #11279, #11585, #11742: ensure that the unsafe Buffer code
  remains memory-safe in concurrent settings.
  Unsynchronized access to Buffer is a programming error and may
  result in wrong behavior, but it should preserve memory-safety.
  (Florian Angeletti and Gabriel Scherer, review by Gabriel Scherer
   and Vincent Laviron, report by David Allsopp)


### Other libraries:

* #9071, #9100, #10935: Reimplement `Thread.exit()` as raising the
  exception `Thread.Exit`, and mark `Thread.exit` as deprecated.
  The new implementation changes the behavior compared with
  the OCaml 4 implementation.  For example, the new implementation
  causes `Fun.finally` finalizers to be run and catch-all exception
  handlers to prevent termination.
  (Jacques-Henri Jourdan and Xavier Leroy, review by Damien Doligez,
  Guillaume Munch-Maccagnoni, Gabriel Scherer, and Enguerrand Decorne)

- #11034: Dynlink library, add a global lock to make dynlinking
  thread-safe.
  (Florian Angeletti, review by Gabriel Scherer)

- #11087: deprecate Thread.wait_timed_read, Thread.wait_timed_write,
  Thread.select, Thread.wait_pid. The same functionality is available in the
  Unix module.
  (Nicolás Ojeda Bär, review by Anil Madhavapeddy)

- #11309, #11424, #11427, #11545: Add Domain.recommended_domain_count.
  (Christiano Haesbaert, Konstantin Belousov, review by David Allsopp,
  KC Sivaramakrishnan, Gabriel Scherer, Nicolás Ojeda Bär)

- #11461, #11466: Fix gethostbyaddr for IPv6 arguments and make it domain-safe
  (Olivier Nicole, Nicolás Ojeda Bär, David Allsopp and Xavier Leroy,
   review by the same)

- #11479: Make Unix.symlink domain-safe on Windows
  (Olivier Nicole, review by Xavier Leroy and David Allsopp)

### Tools:

* #11004: Litmus tests for checking the implementation of the
  memory model.
  (Luc Maranget, review by Gabriel Scherer and Xavier Leroy)

- #11024: Handle alerts in ocamldoc.
  The alert `[@@alert deprecated]` is handled specifically and it's no longer
  needed to duplicate the deprecated annotation (the alert for the compiler and
  the tag for the documentation). Every other alerts also appear in the
  documentation.
  (Jules Aguillon, review by Florian Angeletti)

- #11065: Port the bytecode debugger to 5.0, adding support for effect handlers.
  (Damien Doligez and @fabbing, review by @fabbing and Xavier Leroy)

- #11079: Add the -nobanners option to dumpobj.
  (Sébastien Hinderer, review by Gabriel Scherer and Vincent Laviron)

- #11100: Fix ocamltest to make sure failed tests are not counted as
  "unexpected error".
  (Damien Doligez, review by Sébastien Hinderer)

- #11245: Merge the common code of ocamlcp and ocamloptp into a single module.
  (David Allsopp, review by Sébastien Hinderer)

- #11382: OCamlmktop use a new initialization module "OCamlmktop_init" to
  preserve backward-compatibility with user-module provided modules that install
  toplevel printers.
  (Florian Angeletti, review by Gabriel Scherer and David Allsopp)

### Manual and documentation:

- #11058: runtime/HACKING.adoc tips on debugging the runtime
  (Gabriel Scherer, review by Enguerrand Decorne and Nicolás Ojeda Bär)

- #11093: Add an effect handlers tutorial
  (KC Sivaramakrishnan, review by François Pottier, Gabriel Scherer, François
  Bobot and Wiktor Kuchta)

- #11192: Better documentation for condition variables.
  (François Pottier, review by Luc Maranget, Xavier Leroy, and Wiktor Kuchta)

- #11093: Add tutorials on parallelism features and the relaxed memory model
  (KC Sivaramakrishnan, review by Damien Doligez, Anil Madhavapeddy, Gabriel
  Scherer, Thomas Leonard, Tom Ridge, Xavier Leroy, Luc Maranget, Fabrice
  Buoro, Olivier Nicole, Guillaume Munch-Maccagnoni, Jacques-Henri Jourdan)

- #11640, #11647: Add missing options to the man pages:
   flambda commonly-used options, and negative options (`-no-rectypes`, ... ).
   (Amandine Nangah, review by David Allsopp, Florian Angeletti,
   Sébastien Hinderer, and Vincent Laviron)

- #11676: Fix missing since annotation in the `Sys` and `Format` modules
  (Github user Bukolab99, review by Florian Angeletti)

- #11813: Make new multicore chapters easier to discover, and emphasize impact
  on C bindings.
  (Edwin Török, review by KC Sivaramakrishnan, and Florian Angeletti)

### Compiler user-interface and warnings:

- #9140, #11131: New command-line flag -nocwd to not include implicit
  the current directory to the load path.
  (Thomas Roglin, review by Gabriel Scherer and Nicolás Ojeda Bär)

- #11089: Add 'since <version>' information to compiler warnings.
  (André Maroneze, review by Florian Angeletti and Gabriel Scherer)

- #10909: Disable warning 59 (assignment to immutable blocks) unless flambda
  invariant checks are enabled.
  (Vincent Laviron, review by Gabriel Scherer)

- #10981, #11276: Implement a -cmi-file option for ocamlc and ocamlopt.
  (Sébastien Hinderer, review by Damien Doligez, Daniel Bünzli and
  Florian Angeletti)

* #11049: Stop padding 1-digit compiler minor version numbers.
  (So for instance OCaml 5.0 rather than 5.00)
  (Sébastien Hinderer, review by David Allsopp, Florian Angeletti and
  Xavier Leroy)

- #11253: Deprecate `ocaml script` and `ocamlnat` script where `script` has no
  extension and is an implicit basename.
  (David Allsopp, review by Florian Angeletti and Sébastien Hinderer)

### Internal/compiler-libs changes:

- #10878, #10909: restore flambda after the Multicore merge.
  (Vincent Laviron, review by Gabriel Scherer and Xavier Leroy)

- #10864, #10888: restore afl-fuzz mode for sequential programs.
  (Jan Midtgaard, review by Xavier Leroy and Gabriel Scherer)

- #11008, #11047: rework GC statistics in the Multicore runtime
  (Gabriel Scherer, review by Enguerrand Decorne)

- #11058: basic debugging documentation in runtime/HACKING.adoc
  (Gabriel Scherer, review by Enguerrand Decorne and Nicolás Ojeda Bär)

- #11199: Stop installing topdirs.cmi twice. The toplevel now reads topdirs.cmi
  from +compiler-libs, as the debugger does.
  (David Allsopp, review by Sébastien Hinderer)

- #11007, #11399: META files for the stdlib, compiler-libs and other libraries
  (unix, dynlink, str, runtime_events, threads, ocamldoc) are now installed
  along with the compiler.
  (David Allsopp, Florian Angeletti, Nicolás Ojeda Bär and Sébastien Hinderer,
   review by Daniel Bünzli, Kate Deplaix, Anil Madhavapeddy and Gabriel Scherer)

### Build system:

* #10893: Remove configuration options --disable-force-safe-string and
  DEFAULT_STRING=unsafe as well as --enable-force-safe-string and
  DEFAULT_STRING=safe which are now the default unconditionally.
  (Kate Deplaix, review by Gabriel Scherer and David Allsopp)

- #11092: Build native-code compilers on OpenBSD/aarch64.
  (Christopher Zimmermann, review by Anil Madhavapeddy)

- #11126: Build system: make it possible to choose which ocamldep
  (and flags) to use when computing dependencies for the compiler.
  Add a -no-slash option to ocamldep to let users override -slash.
  (Sébastien Hinderer, review by David Allsopp)

- #11147: Factorize the stdlib-related compilation flags. Make it
  possible to control them consistently through the STDLIBFLAGS
  build variable. Make sure ocamldoc and ocamllex get compiled and
  linked with debugging information (-g).
  (Sébastien Hinderer, review by Gabriel Scherer)

- #11149: Make the bootstrap process reproducible on systems with non-big-endian
  floating point. If the boot/ artefacts are up-to-date, this means that running
  make bootstrap on any platform should not change the images in boot/ and paves
  the way for automated testing that the bootstrap is repeatable.
  (David Allsopp, review by Damien Doligez and Sébastien Hinderer)

- #11160: otherlibs: merge win32unix into unix.
  (Sébastien Hinderer, review by David Allsopp, Nicolás Ojeda Bär,
  Xavier Leroy, Vincent Laviron and Antonin Décimo)

* #11198, #11298: Install the Dynlink, Str and Unix libraries to individual
  subdirectories of LIBDIR. The compiler, debugger and toplevel automatically
  add `-I +lib` if required, but display an alert.
  (David Allsopp, review by Florian Angeletti, Nicolás Ojeda Bär,
   Valentin Gatien-Baron and Sébastien Hinderer)

- #11200: Install ocamlprof's Profiling runtime module to a +profiling,
  removing it from the default namespace.
  (David Allsopp, review by Sébastien Hinderer)

- #11294: Switch minimum required autoconf to 2.71.
  (David Allsopp, review by Xavier Leroy)

- #11097: Build native-code compilers on NetBSD/aarch64
  (Kate Deplaix, review by Anil Madhavapeddy)

### Bug fixes:

- #10790: don't drop variance and injectivity annotations when pretty printing
  `with` constraints (for example, `with type +!'a t = ...`).
  (Florian Angeletti, report by Luke Maurer, review by Matthew Ryan and
   Gabriel Scherer)

- #11167: Fix memory leak from signal stack.
  (Antoni Żewierżejew, review by Gabriel Scherer and Enguerrand Decorne)

- #11112: harden -use-runtime against spaces or quotes in the provided path
  (Gabriel Scherer, report by Brahima Dibassi, review by David Allsopp)

- #11068, #11070: Fix typo in function name given in Unix_error exception for
  Unix.readlink on Windows.
  (David Allsopp, report by Xia Li-yao)

- #10807: Don't duplicate standard handles in the child process
  spawned by win32unix Unix.create_process if the handles were already
  inheritable. Fix broken signalling of EOF on standard handles if
  they were already inheritable.
  (Antonin Décimo, review by Xavier Leroy and Nicolás Ojeda Bär)

- #10868: Fix off-by-1 bug when initializing frame hashtables
  (Jonah Beckford, review by Tom Kelly, Nicolás Ojeda Bär and
  KC Sivaramakrishnan)

- #11077: Make dumpobj compatible with absence of naked pointer support
  (Olivier Nicole and Jan Midtgaard, review by Gabriel Scherer)

- #11111: fix fork() usage in ocamltest C code.
  When calling fork() from C code with the Multicore runtime active,
  one needs to call caml_atfork_hook() on the forked child before it
  can use the OCaml runtime.
  (Gabriel Scherer, review by Xavier Leroy, report by Brahima Dibassi)

- #10809: Use the WSA_FLAG_NO_HANDLE_INHERIT on Windows when creating
  sockets with WSASocket if the cloexec (non-inheritable) parameter is
  true. Fixes a race condition where a child process could inherit the
  socket and deadlock the parent.
  (Antonin Décimo, review by Xavier Leroy)

- #11289, #11405: fix some leaks on systhread termination
  (Fabrice Buoro, Enguerrand Decorne, Gabriel Scherer,
   review by Xavier Leroy and Florian Angeletti, report by Romain Beauxis)

- #11314, #11416: fix non-informative error message for module inclusion
  (Florian Angeletti, report by Thierry Martinez, review by Gabriel Scherer)

- #11358, #11379: Refactor the initialization of bytecode threading,
  This avoids a "dangling pointer" warning of GCC 12.1.
  (Xavier Leroy, report by Armaël Guéneau, review by Gabriel Scherer)

- #11387, module type with constraints no longer crash the compiler in presence
  of both shadowing warnings and the `-bin-annot` compiler flag.
  (Florian Angeletti, report by Christophe Raffalli, review by Gabriel Scherer)

- #11482, #11542: Fix random crash in large closure allocation
  (Damien Doligez, report by Thierry Martinez and Vincent Laviron, review by
   Xavier Leroy)

- #11508, #11509: make Bytes.escaped domain-safe
  (Christiano Haesbaert and Gabriel Scherer,
   review by Xavier Leroy,
   report by Jan Midtgaard and Tom Kelly)

- #11576: Fix bug in Bigarray.Genarray.init in the the case of zero-dimensional
  arrays.
  (Nicolás Ojeda Bär, Jeremy Yallop, report by Masayuki Takeda, review by Jeremy
  Yallop and Florian Angeletti)

- #11587: Prevent integer comparison from being used on pointers
  (Vincent Laviron, review by Gabriel Scherer)

- #11662, #11673: fix a memory leak when using Dynlink,
  the bug was only present in development version of OCaml 5.
  (Stephen Dolan, report by Andre Maroneze, review by Gabriel Scherer)


OCaml 4.14 maintenance version
------------------------------

### Runtime system:

- #11764, #12577: Add prototypes to old-style C function definitions
   and declarations.
  (Antonin Décimo, review by Xavier Leroy and Nick Barnes)

- #11763, #11759, #11861, #12509, #12577: Use strict prototypes on primitives.
  (Antonin Décimo, review by Xavier Leroy, David Allsopp, Sébastien
   Hinderer and Nick Barnes)

### Build system:

- #11590: Allow installing to a destination path containing spaces.
  (Élie Brami, review by Sébastien Hinderer and David Allsopp)

- #12372: Pass option -no-execute-only to the linker for OpenBSD >= 7.3
  so that code sections remain readable, as needed for closure marshaling.
  (Xavier Leroy and Anil Madhavapeddy, review by Anil Madhavapeddy and
  Sébastien Hinderer)

- #12903: Disable control flow integrity on OpenBSD >= 7.4 to avoid
  illegal instruction errors on certain CPUs.
  (Michael Hendricks, review by Miod Vallat)

### Bug fixes:

- #12878: fix incorrect treatment of injectivity for private recursive types.
  (Jeremy Yallop, review by Gabriel Scherer and Jacques Garrigue)

- #12971, #12974: fix an uncaught Ctype.Escape exception on some
  invalid programs forming recursive types.
  (Gabriel Scherer, review by Florian Angeletti, report by Neven Villani)

- #12264, #12289: Fix compact_allocate to avoid a pathological case
  that causes very slow compaction.
  (Damien Doligez, report by Arseniy Alekseyev, review by Sadiq Jaffer)

* #10845 Emit frametable size on amd64 BSD (OpenBSD, FreeBSD, NetBSD) systems
  (emitted for Linux in #8805)
  (Hannes Mehnert, review by Nicolás Ojeda Bär)

- #13448, #13449: fix a code-generation bug on unsafe array accesses
  at type int32, int64, nativeint, which has been introduced in OCaml 4.04.
  (Gabriel Scherer, review by Nicolás Ojeda Bär and Vincent Laviron,
   report by Raphaël Bocquet and Simon Cruanes)

OCaml 4.14.1 (20 December 2022)
------------------------------

### Compiler user-interface and warnings:

- #11184, #11670: Stop calling ranlib on created / installed libraries
  (Sébastien Hinderer and Xavier Leroy, review by the same)

### Build system:

- #11370, #11373: Don't pass CFLAGS to flexlink during configure.
  (David Allsopp, report by William Hu, review by Xavier Leroy and
   Sébastien Hinderer)

- #11487: Thwart FMA test optimization during configure
  (William Hu, review by David Allsopp and Sébastien Hinderer)

### Bug fixes:

- #10768, #11340: Fix typechecking regression when combining first class
  modules and GADTs.
  (Jacques Garrigue, report by François Thiré, review by Matthew Ryan)

- #11204: Fix regression introduced in 4.14.0 that would trigger Warning 17 when
  calling virtual methods introduced by constraining the self type from within
  the class definition.
  (Nicolás Ojeda Bär, review by Leo White)

- #11263, #11267: caml/{memory,misc}.h: check whether `_MSC_VER` is defined
  before using it to ensure that the headers can always be used in code which
  turns on -Wundef (or equivalent).
  (David Allsopp and Nicolás Ojeda Bär, review by Nicolás Ojeda Bär and
   Sébastien Hinderer)

- #11392, #11392: assertion failure with -rectypes and external definitions
  (Gabriel Scherer, review by Florian Angeletti, report by Dmitrii Kosarev)

- #11417: Fix regression allowing virtual methods in non-virtual classes.
  (Leo White, review by Florian Angeletti)

- #11468: Fix regression from #10186 (OCaml 4.13) detecting IPv6 on Windows for
  mingw-w64 i686 port.
  (David Allsopp, review by Xavier Leroy and Sébastien Hinderer)

- #11489, #11496: More prudent deallocation of alternate signal stack
  (Xavier Leroy, report by @rajdakin, review by Florian Angeletti)

- #11516, #11524: Fix the `deprecated_mutable` attribute.
  (Chris Casinghino, review by Nicolás Ojeda Bär and Florian Angeletti)

- #11194, #11609: Fix inconsistent type variable names in "unbound type var"
  messages
  (Ulysse Gérard and Florian Angeletti, review Florian Angeletti and
   Gabriel Scherer)

- #11622: Prevent stack overflow when printing a constructor or record
  mismatch error involving recursive types.
  (Florian Angeletti, review by Gabriel Scherer)

- #11732: Ensure that types from packed modules are always generalised
  (Stephen Dolan and Leo White, review by Jacques Garrigue)

- #11737: Fix segfault condition in Unix.stat under Windows in the presence of
  multiple threads.
  (Marc Lasson, Nicolás Ojeda Bär, review by Gabriel Scherer and David Allsopp)

- #11776: Extend environment with functor parameters in `strengthen_lazy`.
  (Chris Casinghino and Luke Maurer, review by Gabriel Scherer)

- #11533, #11534: follow synonyms again in #show_module_type
  (this had stopped working in 4.14.0)
  (Gabriel Scherer, review by Jacques Garrigue and Florian Angeletti,
   report by Yaron Minsky)

- #11768, #11788: Fix crash at start-up of bytecode programs in
  no-naked-pointers mode caused by wrong initialization of caml_global_data
  (Xavier Leroy, report by Etienne Millon, review by Gabriel Scherer)

- #11803, #11808: on x86, the destination of an integer comparison must be
  a register, it cannot be a stack slot.
  (Vincent Laviron, review by Xavier Leroy, report by
   Emilio Jesús Gallego Arias)

OCaml 4.14.0 (28 March 2022)
----------------------------

### Language features:

- #10462: Add attribute to produce a compiler error for polls.
  (Sadiq Jaffer, review by Mark Shinwell, Stephen Dolan
   and Guillaume Munch-Maccagnoni)

- #10437: Allow explicit binders for type variables.
  (Stephen Dolan, review by Leo White)

- #10441: Remove unnecessary parentheses surrounding immediate objects.
  Allow 'object ... end # f', 'f object ... end', etc.
  (Yan Dong, review by Nicolás Ojeda Bär, Florian Angeletti and Gabriel Scherer)

- #181, #9760, #10740: opt-in tail-modulo-cons (TMC) transformation
    let[@tail_mod_cons] rec map f li = ...
  (Frédéric Bour, Gabriel Scherer, Basile Clément,
   review by Basile Clément and Pierre Chambart,
   tested by Konstantin Romanov)

### Runtime system:

* #9391, #9424: Fix failed assertion in runtime due to ephemerons *set_* and
  *blit_* function during Mark phase
  (François Bobot, reported by Stephen Dolan, reviewed by Damien Doligez)

- #10195, #10680: Speed up GC by prefetching during marking
  (Stephen Dolan, review by Xavier Leroy, Guillaume Munch-Maccagnoni,
   Jacques-Henri Jourdan, Damien Doligez and Leo White)

- #10549: Stack overflow detection and naked pointers checking for ARM64
  (Xavier Leroy, review by Stephen Dolan)

* #10675: Emit deprecation warnings when old C runtime function names
  are used.  This will break C stub code that uses these old names and
  treats warnings as errors.  The workaround is to use the new names.
  (Xavier Leroy and David Allsopp, review by Sébastien Hinderer and
   Damien Doligez)

- #10698, #10726: Free the alternate signal stack when the main OCaml
   code or an OCaml thread stops
  (Xavier Leroy, review by David Allsopp and Damien Doligez)

- #10730, 10731: Fix bug in `Obj.reachable_words` causing a slowdown when called
  multiple time (Alain Frisch, report by ygrek, review by Xavier Leroy)

- #10926: Rename the two internal Windows Unicode functions with `caml_` prefix
  instead of `win_`.
  (David Allsopp, review by Kate Deplaix, Damien Doligez and Xavier Leroy)

### Code generation and optimizations:

- #10578: Increase the number of integer registers used for
  parameter passing on PowerPC (16 registers) and on s390x (8 registers).
  (Xavier Leroy, review by Mark Shinwell)

- #10591, #10615: Tune the heuristic for CSE of integer constants
  so as to avoid excessive CSE on compiler-generated constants
  and long register allocation times.
  (Xavier Leroy, report by Edwin Török, review by Nicolás Ojeda Bär)

- #10595: Tail calls with up to 64 arguments are guaranteed to be compiled
  as tail calls.  To this end, memory locations in the domain state
  are used for passing arguments that do not fit in registers.
  (Xavier Leroy, review by Vincent Laviron)

- #10681: Enforce boolean conditions for the native backend
  (Vincent Laviron, review by Gabriel Scherer)

- #10719: Ensure that build_apply respects Lambda.max_arity
  (Stephen Dolan, review by Xavier Leroy)

- #10728: Ensure that functions are evaluated after their arguments
  (Stephen Dolan, review by Mark Shinwell)

- #10732: Ensure right-to-left evaluation of arguments in cmm_helpers
  (Greta Yorsh, review by Xavier Leroy)

### Standard library:

* #10710: Add UTF tools, codecs and validations to the Uchar, Bytes and
  String modules.
  (Daniel Bünzli, review by Florian Angeletti, Nicolás Ojeda Bär, Alain
   Frisch and Gabriel Scherer)

* #10622: Annotate `Uchar.t` with immediate attribute
  (Hongbo Zhang, reivew by Gabriel Scherer and Nicolás Ojeda Bär)

* #7812, #10475: `Filename.chop_suffix name suff` now checks that `suff`
  is actually a suffix of `name` and raises Invalid_argument otherwise.
  (Xavier Leroy, report by whitequark, review by David Allsopp)

* #10482: mark the Stream and Genlex modules as deprecated, in preparation
  for a future removal.  These modules (without deprecation alert)
  are now provided by the camlp-streams library.
  (Xavier Leroy, review by Nicolás Ojeda Bär)

- #10526: add Random.bits32, Random.bits64, Random.nativebits
  (Xavier Leroy, review by Gabriel Scherer and François Bobot)

* #10568: remove Obj.marshal and Obj.unmarshal
  (these functions have been deprecated for a while and are superseded
   by the functions from module Marshal)
  (François Pottier, review by Gabriel Scherer and Kate Deplaix)

- #10545: Add In_channel and Out_channel modules.
  (Nicolás Ojeda Bär, review by Daniel Bünzli, Simon Cruanes, Gabriel Scherer,
  Guillaume Munch-Maccagnoni, Alain Frisch and Xavier Leroy)

- #10538: add Out_channel.set_buffered and Out_channel.is_buffered to control
  the buffering mode of output channels.
  (Nicolás Ojeda Bär, review by John Whitington, Daniel Bünzli, David Allsopp
  and Xavier Leroy)

* #10583, #10998: Add over 40 new functions in Seq.
  (François Pottier and Simon Cruanes, review by Nicolás Ojeda Bär,
  Daniel Bünzli, Nathanaëlle Courant, Craig Ferguson, Wiktor Kuchta,
  Xavier Leroy, Guillaume Munch-Maccagnoni, Raphaël Proust, Gabriel Scherer
  and Thierry Martinez)

- #10596, #10978: Add with_open_bin, with_open_text and with_open_gen to
  In_channel and Out_channel. Also, add In_channel.input_all.
  (Nicolás Ojeda Bär, review by Daniel Bünzli, Jérémie Dimino, Damien Doligez
  and Xavier Leroy)

- #10658: add detailed information about the current version of OCaml
  to the Sys module of the standard library.
  (Sébastien Hinderer, review by Damien Doligez, Gabriel Scherer, David
  Allsopp, Nicolás Ojeda Bär, Vincent Laviron)

- #10642: On Windows, Sys.remove and Unix.unlink now remove symlinks
  to directories instead of raising EACCES. Introduce
  caml/winsupport.h to hold more common code between the runtime,
  lib-sys, and win32unix.
  (Antonin Décimo, review by David Allsopp and Xavier Leroy)

- #10737: add new ephemeron API for forward compatibility with Multicore
  OCaml.
  (Damien Doligez, review by Stephen Dolan)

- #10786: The implementation of Complex.norm now uses Float.hypot.
  (Christophe Troestler, review by David Allsopp and Xavier Leroy)

### Other libraries:

- #10192: Add support for Unix domain sockets on Windows and use them
  to emulate Unix.socketpair (only available on Windows 1803+)
  (Antonin Décimo, review by David Allsopp)

- #10469: Add Thread.set_uncaught_exception_handler and
  Thread.default_uncaught_exception_handler.
  (Enguerrand Decorne, review by David Allsopp)

- #10697: Bindings of dup and dup2 in win32unix now correctly call
  WSADuplicateSocket on sockets instead of DuplicateHandle.
  (Antonin Décimo, review by Xavier Leroy and Nicolás Ojeda Bär)

* #10926, #11336: Ensure all C functions in the Unix library are prefixed with
  `caml_`.
  (David Allsopp, review by Kate Deplaix, Damien Doligez and Xavier Leroy)

- #10951: Introduce the Thread.Exit exception as an alternative way to
  terminate threads prematurely.  This alternative way will become
  the standard way in 5.0.
  (Xavier Leroy, review by Florian Angeletti)

### Tools:

- #9701: Release bytecode only after collecting backtrace information
  for exceptions, same for dynamic loaded code compiled from toplevel on
  ocamlnat.
  (Renato Alencar, reported by Krzysztof Leśniak, reviewed by Gabriel Scherer)

- #10839: Fix regression of #show when printing class type
  (Élie Brami, review by Florian Angeletti)

- #3959, #7202, #10476: ocaml, in script mode, directive errors
  (`#use "missing_file";;`) use stderr and exit with an error.
  (Florian Angeletti, review by Gabriel Scherer)

- #10438: add a new toplevel cli argument `-e <script>` to
  run script passed to the toplevel.
  (Pavlo Khrystenko, review by Gabriel Scherer)

- #10524: Directive argument type error now shows expected and received type.
  (Wiktor Kuchta, review by Gabriel Scherer)

- #10560: Disable colors if the env variable `NO_COLOR` is set.  If
  `OCAML_COLOR` is set, its setting takes precedence over `NO_COLOR`.
  (Nicolás Ojeda Bär, report by Gabriel Scherer, review by Daniel Bünzli,
  Gabriel Scherer and David Allsopp)

- #10565: Toplevel value printing: truncate strings only after 8 bytes.
  (Wiktor Kuchta, review by Xavier Leroy)

- #10527: Show "#help;; for help" at toplevel startup
  (Wiktor Kuchta, review by David Allsopp and Florian Angeletti)

- #10846: add the `-shape` command-line option to ocamlobjinfo. When reading a
  `cmt` file, shape information will only be shown if that option is used.
  (Ulysse Gérard, review by Florian Angeletti)

### Debugging:

- #10517, #10594: when running ocamldebug on a program linked with the
  threads library, don't fail immediately; instead, allow debugging
  until the program creates a thread for the first time, then fail cleanly.
  (Xavier Leroy, report by @anentropic, review by Gabriel Scherer)

- #9621: Pack the ocamldebug modules to minimize clashes
  (Raphael Sousa Santos, review by Vincent Laviron and Gabriel Scherer)

### Manual and documentation:

- #7812, #10475: reworded the description of the behaviors of
  float->int conversions in case of overflow, and of iterators
  in case of concurrent modifications.
  (Xavier Leroy, report by whitequark, review by David Allsopp)

- #8697, #10666: add M, m, n options of the OCAMLRUNPARAM to manual and man page
  for ocamlrun command line options
  (Dong An and Anukriti Kumar, review by David Allsopp, Gabriel Scherer
   and Damien Doligez)

- #10281, #10685: Add description of C compiler on macOS and Windows platforms.
  (Dong An, review by Xavier Leroy and David Allsopp)

- #10397: Document exceptions raised by Unix module functions on Windows
  (Martin Jambon, review by Daniel Bünzli, David Allsopp, Damien Doligez,
   Xavier Leroy, and Florian Angeletti)

- #10589: Fix many typos (excess/inconsistent spaces) in the HTML manual.
  (Wiktor Kuchta, review by Florian Angeletti)

- #10605: manual, name few css classes to ease styling and maintainability.
  (Florian Angeletti, review by Wiktor Kuchta and Gabriel Scherer)

- #10668, #10669: the changelog (this file), LICENSE and README files are now
  installed as part of the distribution. The destination directory can be
  customized using the `--docdir` argument to `./configure`.
  (Nicolás Ojeda Bär, report by Daniel Bünzli, review by David Allsopp,
  Sébastien Hinderer, and Daniel Bünzli)

- #10671, #10672: webman: Fix misalignments in unordered lists by changing the
  CSS for coloring bullets
  (Wiktor Kuchta, review by Florian Angeletti)

- #11107: Lifted comments in the Parsetree module into actual documentation.
  (Paul-Elliot Anglès d'Auriac, review by Florian Angeletti)

- #11120, #11133: man pages, add missing warning entries and add mnemonic names
  to the list of warnings.
  (Florian Angeletti, report by Kate Deplaix, review by Gabriel Scherer)

### Compiler user-interface and warnings:

- #10328, #10780: Give more precise error when disambiguation could not
  possibly work.
  (Leo White, review by Gabriel Scherer and Florian Angeletti)

- #10361: Improve error messages for mismatched record and variant
  definitions.
  (Florian Angeletti, review by Gabriel Radanne and Gabriel Scherer)

- #10407: Produce more detailed error messages that contain full error traces
  when module inclusion fails.
  (Antal Spector-Zabusky, review by Florian Angeletti)

- #10531: add naked_pointers to ocamlc -config exporting NAKED_POINTERS from
  Makefile.config.
  (Damien Doligez, review by Mark Shinwell and Gabriel Scherer)

- #9116, #9118, #10582: Fix single-line source highlighting in the
  presence of tabs
  (Armaël Guéneau, review by Gabriel Scherer,
   split off from #9118 by Kate Deplaix, report by Ricardo M. Correia)

- #10488: Improve type variable name generation and recursive type detection
  when printing type errors; this ensures that the names given to type variables
  are always reused in the following portion of the trace and also removes
  spurious `as 'a`s in types.
  (Antal Spector-Zabusky, review by Florian Angeletti)

- #10794: Clarify warning 57 (Ambiguous or-pattern variables under guard)
  (Wiktor Kuchta, review by Gabriel Scherer)

### Internal/compiler-libs changes:

- #1599: add unset directive to ocamltest to clear environment variables before
  running tests.
  (David Allsopp, review by Damien Doligez and Sébastien Hinderer)

- #8516: Change representation of class signatures
  (Leo White, review by Thomas Refis)

- #9444: -dtypedtree, print more explicitly extra nodes in pattern ast.
  (Frédéric Bour, review by Gabriel Scherer)

- #10337: Normalize type_expr nodes on access
  One should now use accessors such as get_desc and get_level to access fields
  of type_expr, rather than calling manually Btype.repr (which is now hidden
  in Types.Transient_expr).
  (Jacques Garrigue and Takafumi Saikawa,
   review by Florian Angeletti and Gabriel Radanne)

- #10474: Force normalization on access to row_desc
  Similar to #10337. Make row_desc an abstract types, with constructor
  create_row and accessors defined in Types rather than Btype.
  A normalized view row_desc_repr is provided for convenience.
  (Jacques Garrigue and Takafumi Saikawa,
   review by Leo White and Florian Angeletti)

- #10541: Make field_kind and commutable abstract, enforcing correct access
  (Jacques Garrigue and Takafumi Saikawa,
   review by Thomas Refis and Florian Angeletti)

- #10575: add a -dump-dir flag, which redirects all debugging printer
   (`-dprofile`, `-dlambda`, ...) to the target directory
  (Florian Angeletti, review by Thomas Refis and Gabriel Scherer)

* #10627: Make row_field abstract
  Completes #10474 by making row_field abstract too.
  An immutable view row_field_view is provided, and one converts between it
  and row_field via inj_row_field and row_field_repr.
  (Jacques Garrigue and Takafumi Saikawa, review by Florian Angeletti)

- #10433: Remove the distinction between 32-bit aligned and 64-bit aligned
  64-bit floats in Cmm.memory_chunk.
  (Greta Yorsh, review by Xavier Leroy)

- #10434: Pun labelled arguments with type constraint in function applications.
  (Greta Yorsh, review by Nicolas Chataing and Nicolás Ojeda Bär)

- #10470: Remove unused `cstr_normal` field from the `constructor_description`
  type
  (Nicolas Chataing, review by Gabriel Scherer)

- #10382: Don't repeat environment entries in Typemod.check_type_decl
  (Leo White, review by Gabriel Scherer and Florian Angeletti)

- #10472: refactor caml_sys_random_seed to ease future Multicore changes
  (Gabriel Scherer, review by Xavier Leroy)

- #10487: Move logic to get the type path from a constructor return type in
  Types
  (Nicolas Chataing, review by Jacques Garrigue)

- #10555: Do not use ghost locations for type constraints
  (Nicolás Ojeda Bär, report by Anton Bachin, review by Thomas Refis)

- #10598, #10616: fix an exponential blow-up when typechecking nested module
  types
  (Florian Angeletti, report and review by Stephen Dolan)

- #10559: Evaluate signature substitutions lazily
  (Stephen Dolan, review by Leo White)

- #8776, #10624: Fix compilation time regression introduced in 4.08
  (Nicolás Ojeda Bär, fix by Leo White, report by Alain Frisch, review by Thomas
  Refis)

- #10618: Expose more Pprintast functions
  (Guillaume Petiot, review by Gabriel Scherer)

- #10637: Outcometree: introduce a record type for constructors
  (Gabriel Scherer, review by Thomas Refis)

- #10516: refactor the compilation of the 'switch' construct
  (Gabriel Scherer, review by Wiktor Kuchta and Luc Maranget)

- #10670: avoid global C state in the RE engine for the "str" library
  (Xavier Leroy, review by Gabriel Scherer)

- #10678: Expose descriptions in Warnings module
  (Leo White, review by Gabriel Scherer and Alain Frisch)

- #10690: Always build ocamltoplevel.cmxa
  (David Allsopp, review by Gabriel Scherer)

- #10692: Expose Parse.module_type and Parse.module_expr
  (Guillaume Petiot, review by Gabriel Scherer)

- #10714: Add X86_proc.with_internal_assembler for temporarily changing the
  assembler used by the backend.
  (David Allsopp, review by Gabriel Scherer)

- #10715: Allow the assembler and loader to be substituted in ocamlnat, for
  example to be replaced with a binary emitter.
  (David Allsopp and Nathan Rebours, review by Louis Gesbert,
  Nicolás Ojeda Bär and Gabriel Scherer)

- #10718, #11012: Add "Shape" information to the cmt files. Shapes are an
  abstraction of modules that can be used by external tooling to perform
  definition-aware operations.
  (Ulysse Gérard, Thomas Refis and Leo White, review by Florian Angeletti)

- #10742: strong call-by-need reduction for shapes
  (Gabriel Scherer and Nathanaëlle Courant,
   review by Florian Angeletti, Ulysse Gérard and Thomas Refis)

### Build system:

- #10835 Disable DT_TEXTREL warnings on x86 32 bit architecture by passing
  -Wl,-z,notext in mksharedlib and mkmaindll. Fixes relocation issues, reported
  in #9800, making local patches in Debian, Alpine, and FreeBSD superfluous.
  (Hannes Mehnert with Kate Deplaix and Stéphane Glondu, review by Xavier Leroy)

- #10717: Simplify the installation of man pages
  (Sébastien Hinderer, review by David Allsopp)

- #10739: Stop installing extract_crc
  (Sébastien Hinderer, review by David Allsopp, Daniel Bünzli, Xavier Leroy
  and Gabriel Scherer)

- #10797: Compile with -d2VolatileMetadata- on supporting versions of Visual
  Studio. This suppresses the addition of .voltbl sections and eliminates
  linking errors in systhreads.
  (David Allsopp, review by Jonah Beckford and Sébastien Hinderer)

### Bug fixes:

- #9214, #10709: Wrong unmarshaling of function pointers in debugger mode.
  This was causing ocamldebug to crash when running some user-defined printers.
  (Xavier Leroy, report by Rehan Malak, review by Gabriel Scherer and
   Vincent Laviron)

- #10364: Improve detection of ambiguity in case bodies.
  (Jacques Garrigue, review by Thomas Refis)

- #10473: Add CFI directives to RISC-V runtime and asmcomp.
  This allows stacktraces to work in gdb through C and OCaml calls.
  (Edwin Török, review by Nicolás Ojeda Bär and Xavier Leroy)

- #10539: Field kinds should be kept when copying types
  Losing the sharing meant that one could desynchronize them between several
  occurrences of self, allowing a method to be both public and hidden,
  which broke type soundness.
  (Jacques Garrigue, review by Leo White)

- #10542: Fix detection of immediate64 types through unboxed types.
  (Leo White, review by Stephen Dolan and Gabriel Scherer)

- #10590: Some typechecker optimisations
  (Stephen Dolan, review by Gabriel Scherer and Leo White)

- #10633: Stack overflow recovery in ocamlopt for AMD64/Linux and ARM/Linux
  was not restoring the minor heap pointer correctly
  (Stephen Dolan, review by Xavier Leroy)

- #10659: Fix freshening substitutions on imported modules
  (Leo White and Stephen Dolan, review by Matthew Ryan)

- #10677, #10679: Fix detection of CC as gcc in configure (allow for
  triplet-prefixed GCC) and fix all C compiler detection when CC is a path
  rather than a basename.
  (David Allsopp, report by Fabian @copy, review by Gabriel Scherer)

- #10690: Add --enable-native-toplevel to configure to enable installing
  ocamlnat as part of the main build (default is not to install it)
  (David Allsopp, review by Gabriel Scherer)

- #10693: Fix ident collision in includemod
  (Leo White, review by Matthew Ryan)

- #10702: Fix cast of more strictly aligned pointer in win32unix
  implementation of stat
  (Antonin Décimo, review by David Allsopp)

- #10712: Type-check toplevel terms in the native toplevel in the same way as
  the bytecode toplevel. In particular, this fixes the loss of type variable
  names in the native toplevel.
  (Leo White, review by David Allsopp and Gabriel Scherer)

- #10735: Uncaught unify exception from `build_as_type`
  (Jacques Garrigue, report and review by Leo White)

- #10763, #10764: fix miscompilation of method delegation
  (Alain Frisch, review by Vincent Laviron and Jacques Garrigue)

- #10822, #10823: Bad interaction between ambivalent types and subtyping
  coercions (Jacques Garrigue, report and review by Frédéric Bour)

- #10836, #10952: avoid internal typechecker errors when checking signature
  inclusion in presence of incompatible types.
  (Florian Angeletti, report by Craig Ferguson, review by Gabriel Scherer)

- #10849: Display the result of `let _ : <type> = <expr>` in the native
  toplevel, as in the bytecode toplevel.
  (David Allsopp, report by Nathan Rebours, review by Gabriel Scherer)

- #10853: `Obj.reachable_words` could crash if called after a marshaling
  operation in `NO_SHARING` mode.
  (Xavier Leroy, report by Anil Madhavapeddy, review by Alain Frisch)

- #10907, #10959: Wrong type inferred from existential types
  (Jacques Garrigue and Gabriel Scherer, report by @dyzsr, review by Leo White)

- #10688: Move frame descriptor table from `rodata` to `data` section on
  RISC-V.  Improves support for building DLLs and PIEs. In particular, this
  applies to all binaries in distributions that build PIEs by default (eg
  Gentoo and Alpine).
  (Alex Fan, review by Gabriel Scherer)

- #11031: Exception handlers restore the rbp register when using frame-pointers
  on amd64.
  (Fabrice Buoro, with help from Stephen Dolan, Tom Kelly and Mark Shinwell,
  review by Xavier Leroy)

- #11025, #11036: Do not pass -no-pie to the C compiler on musl/arm64
  (omni, Kate Deplaix and Antonio Nuno Monteiro, review by Xavier Leroy)

- #11101, #11109: A recursive type constraint fails on 4.14
  (Jacques Garrigue, report and review by Florian Angeletti)

- #11118: Fix integer overflow on 64-bit Windows when indexing bigarrays (which
  could lead to a segmentation fault).
  (Roven Gabriel, review by Nicolás Ojeda Bär and Xavier Leroy)

OCaml 4.13 maintenance branch
-----------------------------

### Bug fixes

- #10661, #10662: fix a bug with classes named "row"
  (Gabriel Scherer, report by Nicolás Ojeda Bär)


OCaml 4.13.0 (24 September 2021)
--------------------------------

### Progress towards Multicore:

- #10039: Safepoints
  Add poll points to native generated code. These are effectively
  zero-sized allocations and fix some signal and remembered set
  issues. Also multicore prerequisite.
  (Sadiq Jaffer, Stephen Dolan, Damien Doligez, Xavier Leroy,
   Anmol Sahoo, Mark Shinwell, review by Damien Doligez, Xavier Leroy,
   and Mark Shinwell)

- #9876: do not cache the young_limit GC variable in a processor register.
  This affects the ARM64, PowerPC and RISC-V ports, making signal handling
  and minor GC triggers more reliable, at the cost of a small slowdown.
  (Xavier Leroy, review by Nicolás Ojeda Bär)

### Language features (highlights):

- #9584, #7074: Allow to name existentials in pattern-matching
  One can now write '(Cstr (type a) (x, y : int * a))' to give a name to
  existentials freshly introduced by GADT constructors.
  (Jacques Garrigue, review by Leo White and Gabriel Scherer)

### Compiler user-interface and warnings (highlights):

- #9331: Improve error messages for functor application and functor types.
  (Florian Angeletti and Gabriel Radanne, review by Leo White)

* #10118, #10140: enable warning 6 [labels-omitted] by default.
  The following now warns:
    let f ~x y = ... in f 3 5
  the callsite (f 3 5) has to be turned into (f ~x:3 5).
  This prevents mistakes where two arguments of the same types are swapped.
  (Note: Dune already enables this warning by default.)
  (Gabriel Scherer, review by Xavier Leroy and Florian Angeletti,
   report by ygrek)

### Manual and documentation (highlights):

- #10247: Add initial tranche of examples to reference manual.
  Adds some eighty examples to the reference manual, principally to the
  expressions and patterns sections.
  https://ocaml.org/releases/4.13/manual/patterns.html
  (John Whitington, review by Xavier Leroy, Gabriel Scherer, @Fourchaux, and
  Florian Angeletti)

- #9987, #9988, #9996, #9997: add an odoc mode for the documentation
  of the standard library and compiler library
  (Florian Angeletti, review by David Allsopp, Sébastien Hinderer,
   and Gabriel Scherer)

### Standard library (highlights):

- #944: Add some missing C99 float operations.  `Stdlib` now contains
  the inverse hyperbolic functions
    `acosh`, `asinh`, and `atanh`.
  These functions were also added to module `Stdlib.Float` together with
    `exp2`, `log2`, `cbrt`, `erf`, and `erfc`.
  Full support on MSVC requires VS2013+ but emulated versions are
  still available (for now) for older compilers.
  (Markus Mottl, review by David Allsopp, Olivier Andrieu, Florian Angeletti,
  Nicolás Ojeda Bär, Daniel Bünzli, Fabian @copy, Pascal Cuoq, Damien
  Doligez, Sébastien Hinderer, Jacques-Henri Jourdan, Xavier Leroy, Guillaume
  Melquiond, Perry E. Metzger, Runhang Li, Gabriel Scherer, Mark Shinwell,
  Bernhard Schommer and Christophe Troestler)

- #9582: Add Array.{find_opt,find_map,split,combine}.
  (Nicolás Ojeda Bär, review by Daniel Bünzli and Gabriel Scherer)

- #9533: Added String.starts_with and String.ends_with.
  (Bernhard Schommer, review by Daniel Bünzli, Gabriel Scherer and
  Alain Frisch)

### Code generation and optimizations (highlights):

- #10404: Add a generic backward dataflow analyzer and use it to speed up
  liveness analysis
  (Xavier Leroy, review by Gabriel Scherer, Greta Yorsh, Mark Shinwell)

- #10414: Avoid compilation times exponential in the nesting of loops
  in the spilling and reloading passes
  (Xavier Leroy, review by Vincent Laviron)

### Internal typechecker changes (highlights):

- #10170: Maintain more structural information in type-checking errors
  A mostly-internal change that preserves more information in errors
  during type checking; most significantly, it split the errors from
  unification, moregen, and type equality into three different types.
  (Antal Spector-Zabusky and Mekhrubon Turaev, review by Leo White,
  Florian Angeletti, and Jacques Garrigue)

- #9994: Make Types.type_expr a private type, and abstract marking mechanism
  (Jacques Garrigue and Takafumi Saikawa,
   review by Gabriel Scherer and Leo White)

### Runtime system (highlights):

- #10188, #10213: Switch the default allocation policy to best-fit and adjust
  the default overhead parameter accordingly.
  (Damien Doligez, review by Josh Berdine and Xavier Leroy)

- #10549: Stack overflow detection and naked pointers checking for ARM64
  (Xavier Leroy, review by Stephen Dolan)

- #9934: Optimise sweeping using prefetching.
  (Stephen Dolan and Will Hasenplaugh, review by David Allsopp, Xavier
   Leroy and Damien Doligez, benchmarking by Shubham Kumar and KC
   Sivaramakrishnan)

- #10194: Change compaction-triggering heuristic: use the overhead measured
  by the previous GC cycle instead of an indirect (and noisy) computation
  of the current overhead.
  (Damien Doligez, review by Stephen Dolan)

- #10449: Fix major GC work accounting (the GC was running too fast).
  (Damien Doligez, report by Stephen Dolan, review by Nicolás Ojeda Bär and
   Sadiq Jaffer)


### Language features:

- #10013: Let-punning
  Allow 'let* x in ...' and 'let%ext x in ...' as shorthand for
    'let* x = x in ...' and 'let%ext x = x in ...' respectively.
  (Stephen Dolan, review by Gabriel Scherer)

- #10133: module type substitutions
  Allow 'SIG with module type T = F(X).S', 'SIG with module type T := sig end'
  and their local equivalent `module type T := sig type u end`
  (Florian Angeletti, review by Gabriel Radanne and Leo White)

### Type system:

* #10081: Typecheck `x |> f` and `f @@ x` as `(f x)`
  (Alain Frisch, review by Jacques Garrigue, Josh Berdine and Thomas Refis)

### Runtime system:

- #10318: Windows Unicode runtime functions are no longer marked as
  experimental.
  (Nicolás Ojeda Bär, review by David Allsopp)

- #9284: Add -config option to display the configuration of ocamlrun on stdout,
  including the search path for shared stub libraries.
  (David Allsopp, review by Xavier Leroy)

- #9919: Introduce caml_record_backtraces and update Interfacing with C to
  refer to it (previous instruction to use caml_record_backtrace primitive was
  not possible without defining CAML_INTERNALS)
  (David Allsopp, review by Xavier Leroy)

- #10102: Ignore PROFINFO_WIDTH if WITH_PROFINFO is not defined (technically
  a breaking change if the configuration system was being abused before).
  (David Allsopp, review by Xavier Leroy)

- #10107: Ensure modules compiled with -afl-instrument can still link on
  platforms without AFL support.
  (David Allsopp, review by Xavier Leroy)

* #10098: Improve command-line parsing in ocamlrun: strictly recognise options,
  be more informative for `ocamlrun -I` and support `--` for terminating options
  parsing.
  (David Allsopp, review by Xavier Leroy)

- #10101: Add -help/--help option to ocamlrun.
  (David Allsopp, review by Xavier Leroy)

- #10136: Minor clean-ups in runtime/io.c and runtime/caml/io.h
  (Xavier Leroy, review by David Allsopp and Guillaume Munch-Maccagnoni)

- #10171: Tweak the naked pointers checker so that processes which trigger the
  alarm always exit with non-zero status (i.e. exit(0) becomes exit(70)).
  (David Allsopp, review by Xavier Leroy)

- #10212: Simplify and improve the Windows-specific code that connects
  to the debugger via a socket.
  (Antonin Décimo, review by Xavier Leroy)

- #10217: Fix a segfault in a corner case of compaction (reported in #9853)
  (Damien Doligez, report by Sadiq Jaffer, review by Stephen Dolan)

- #10250, #10266: Dynamically allocate alternate signal stacks to
   accommodate changes in Glibc 2.34.
  (Xavier Leroy, reports by Tomasz Kłoczko and Richard Jones, review by Anil
   Madhavapeddy, Stephen Dolan, and Florian Angeletti)

### Code generation and optimizations:

- #1400: Add an optional invariants check on Cmm, which can be activated
  with the -dcmm-invariants flag
  (Vincent Laviron, with help from Sébastien Hinderer, review by Stephen Dolan
   and David Allsopp)

- #9562, #367: Allow CSE of immutable loads across stores
  (Stephen Dolan, review by Mark Shinwell)

- #9937: improvements in ARM64 code generation (constants, sign extensions)
  (Xavier Leroy, review by Stephen Dolan)

- #10228: Better code-generation for inlined comparisons
  (Stephen Dolan, review by Alain Frisch and Xavier Leroy)

- #10244: Optimise Int32.unsigned_to_int
  (Fabian Hemmer, review by Stephen Dolan and Xavier Leroy)

- #10302, #10303: Fix incorrect instruction selection for string constant loads
  on ppc.
  (David Allsopp, review by Stephen Dolan)

- #10349: Fix destroyed_at_c_call on RISC-V
  (Mark Shinwell, review by Nicolás Ojeda Bär)

- #10419: Add %frame_pointers primitive which is true only in native code with
  frame pointers mode enabled.
  (David Allsopp, review by Vincent Laviron and Mark Shinwell)

### Standard library:

- #9448: Add String.{empty,cat} as dual of Bytes.{empty,cat},
  String.{of,to}_bytes as aliases of Bytes.{to,of}_string,
  Bytes.split_on_char as dual of String.split_on_char, and binary decoding
  functions in String to match those in Bytes.
  (David Allsopp, review by Damien Doligez, Gabriel Scherer and others)

- #9487, #9489: Add Random.full_int which allows 62-bit bounds on 64-bit
  systems.
  (David Allsopp, request by François Berenger, review by Xavier Leroy and
   Damien Doligez)

- #9961: Add Array.fold_left_map.
  (Craig Ferguson, review by Damien Doligez)

- #10097: Lazy.map, Lazy.map_val: ('a -> 'b) -> 'a Lazy.t -> 'b Lazy.t
  (map f x) is always (lazy (f (force x))), whereas (map_val f x)
  applies f directly if x is already forced.
  (Gabriel Scherer, review by Nicolás Ojeda Bär, Alain Frisch, Xavier Leroy,
   Daniel Bünzli and Stephen Dolan)

- #10242: Added convenience pretty printer for Either.t in the Format module.
  (Oghenevwogaga Ebresafe, review by Nicolás Ojeda Bär,
  Gabriel Scherer and Xavier Van de Woestyne)

- #10352: Seq.(concat : 'a t t -> 'a t)
  Seq.concat_map as an alias to Seq.flat_map,
  (Gabriel Scherer, review by Ulugbek Abdullaev and Daniel Bünzli
   and Nicolás Ojeda Bär and Florian Angeletti)

- #882: Add fold_left, fold_right, exists and for_all to String/Bytes
  (Yotam Barnoy, review by Alain Frisch and Jeremy Yallop)

- #4070, #10398: small optimization of Stdlib.{frexp,modf}.
  (Markus Mottl, Nicolás Ojeda Bär, review by Gabriel Scherer)

- #10389, #10391, #10392: Add {Int,Int32,Int64,Nativeint}.{min,max}.
  (Nicolás Ojeda Bär and Alain Frisch, review by Xavier Leroy)

- #10430: Add Format.print_bytes and Format.pp_print_bytes.
  (Gabriel Radanne, review by Gabriel Scherer and David Allsopp)

### Other libraries:

* #10084: Unix.open_process_args* functions now look up the program in the PATH.
  This was already the case under Windows, but this is now also done under
  Unix. Note that previously the program was interpreted relative to the current
  directory.
  (Nicolás Ojeda Bär, review by Gabriel Scherer and Xavier Leroy)

- #10047: Add `Unix.realpath`
  (Daniel Bünzli, review by David Allsopp, Josh Berdine and Gabriel Scherer)

- #10184: Remove expensive debug assertion from dynlink.
  (Leo White, review by David Allsopp and Xavier Leroy)

- #10185: Consider that IPv6 is always enabled on Windows.
  (Antonin Décimo, review by David Allsopp and Xavier Leroy)

- #10306: Map WSA error code to Unix errno for sockopt and getsockname
  functions (Antonin Décimo, review by David Allsopp)

- #10309: Properly return EBADF on error in Unix.descr_of_{in,out}_channel on
  Win32 and map Windows error correctly in Unix.truncate and Unix.ftruncate on
  Win32.
  (David Allsopp, review by Nicolás Ojeda Bär)

### Tools:

- #10139: Adds a -nonavbar option to ocamldoc, to remove confusing
  'Up', 'Previous' and 'Next' links
  (John Whitington, review by David Allsopp)

- #8645, #10363: ocamldoc: escape `<`, `>`, and `&` in html backend.
  (Florian Angeletti, report by Wim Lewis, review by Gabriel Scherer)

### Manual and documentation:

- #9525, #10402: document that ocamldoc only creates paragraphs
  at the toplevel of documentation comments
  (Florian Angeletti, report by Hendrik Tews, review by Gabriel Scherer)

- #10206: Split labels and polymorphic variants tutorials in two.
  Moves the GADTs tutorial from the Language Extensions chapter
  to the tutorials.
  (John Whitington, review by Florian Angeletti and Xavier Leroy)

- #9786, #10181: improved documentation of Unix.{in,out}_channel_of_descr
  with respect to closing.
  (Xavier Leroy, report by Jacques-Henri Jourdan, review by Guillaume
   Munch-Maccagnoni, Gabriel Scherer, Jacques-Henri Jourdan)

- #10139: Use the new -nonavbar option to improve navigation within
  the reference manual stdlib documentation.
  (John Whitington, review by David Allsopp)

- #1351: Document `-output-complete-obj` option in the manual.
  (François Bobot, Nicolás Ojeda Bär, review by Daniel Bünzli and Damien
  Doligez)

- #9632: Document incremental build solutions with opam
  (Vincent Laviron, review by Daniel Bünzli and Gabriel Scherer)

- #10497: Styling changes in the post-processed HTML manual (webman)
  (Wiktor Kuchta, review by Florian Angeletti)

- #10605: manual, name few css classes to ease styling and maintainability.
  (Florian Angeletti, review by Wiktor Kuchta and Gabriel Scherer)

### Compiler user-interface and warnings:

- #1737, #2092, #7852, #7859, #10405, #10417: Update locations during
  destructive substitutions
  (Thomas Refis, review by Gabriel Radanne, report by Hugo Heuzard)

- #2245: Improve error message for link order error in bytecode
  (Pierre Chambart, review by Jérémie Dimino and Gabriel Scherer)

- #8732, improved error messages for invalid private row type definitions.
  For instance, [ type t = private [< `A > `A ] ] .
  (Florian Angeletti, review by Jacques Garrigue, Thomas Refis,
   and Gabriel Scherer)

- #9407: optional warning for missing mli interface file
  (Anukriti Kumar, review by Florian Angeletti)

- #9960, #10619: extend ocamlc/ocamlopt's -o option to work when
  compiling C files
  (Sébastien Hinderer, reported by Daniel Bünzli, review by
  Florian Angeletti and Gabriel Scherer)

- #10095: minor simplifications to some syntax error messages.
  (François Pottier, review by Gabriel Scherer and Frédéric Bour.)

- #10196, #10197: better error message on empty character literals ''.
  (Gabriel Scherer, review by David Allsopp and Florian Angeletti
   and Daniel Bünzli, report by Robin Björklin)

- #8877: Call the linker when ocamlopt is invoked with .o and .a files only.
  (Greta Yorsh, review by Leo White)

- #10207, #10312: deprecate consecutive letters in warning
  specifications.
  The form `-w aBcD` was equivalent to `-w -a+b-c+d`.
  It is now deprecated to improve the coexistence with warning mnemonics.
  However, using isolated single letter is not deprecated to allow the form
  `-w "A-32..50-45"`.
  (Florian Angeletti, review by Damien Doligez and Gabriel Scherer)

- #10232: Warning for unused record fields.
  (Leo White, review by Florian Angeletti)

### Internal/compiler-libs changes:

- #9243, simplify parser rules for array indexing operations
  (Florian Angeletti, review by Damien Doligez and Gabriel Scherer)

- #9650, #9651: keep refactoring the pattern-matching compiler
  (Gabriel Scherer, review by Thomas Refis and Florian Angeletti)

- #9827: Replace references with functions arguments in Simplif
  (Anukriti Kumar, review by Vincent Laviron and David Allsopp)

- #10007: Driver.compile_common: when typing a .ml file, return the
  compilation unit signature (inferred or from the .cmi) in addition
  to the implementation and the coercion.
  (Leandro Ostera, review by Gabriel Scherer and Thomas Refis)

- #10045: Add libext variable to ocamltest and enable C# tests on mingw
  (David Allsopp, review by Gabriel Scherer)

* #10061, #10078, #10187: remove library `ocamlopttoplevel`, remove modules
  `Opttoploop`, `Opttopstart`, which are replaced by `Toploop` and `Topstart` in
  library `ocamltoplevel`, made available in native code.
  (Louis Gesbert, review by Jeremie Dimino, Mark Shinwell and Gabriel Radanne)

- #10124: remove duplicated code from the native toplevel, split toplevel
  implementation into the shared part (`Topcommon`, etc.) and specific ones
  (`Topeval`, `Trace`, `Topmain`).
  (Louis Gesbert, review by Jeremie Dimino and Gabriel Radanne)

- #10086: add the commands `make list-parse-errors` and `make
  generate-parse-errors` to generate a set of syntactically incorrect
  sentences that covers all error states of the LR automaton. Add these
  sentences to the test suite. This can be used to evaluate the quality of the
  parser's syntax error messages and (in the future) to evaluate the impact of
  changes in the parser.
  (François Pottier, review by Gabriel Scherer and Xavier Leroy.)

- #10090: Distinguished constructors for ref variables at lambda level
  (Keryan Didier, review by Gabriel Scherer and Vincent Laviron)

- #10113: add a `-timeout` option to ocamltest and use it in the test suite.
  (Xavier Leroy and Gabriel Scherer, review by Sébastien Hinderer
   and David Allsopp)

* #10169, #10270, #10301, #10451: Use capitalized module names in the Standard
  Library prefixing scheme to match Dune, e.g. Stdlib__String instead of
  Stdlib__string. This is a breaking change only to code which attempted to use
  the internal names before. The Standard Library generated by the Dune rules is
  now equivalent to the main build (the Dune rules still do not generate a
  distributable compiler).
  (David Allsopp and Mark Shinwell, review by Gabriel Scherer)

- #10327: Add a subdirectories variable and a copy action to ocamltest
  (Sébastien Hinderer, review by David Allsopp)

* #10337: Normalize type_expr nodes on access
  One should now use accessors such as get_desc and get_level to access fields
  of type_expr, rather than calling manually Btype.repr (which is now hidden
  in Types.Transient_expr).
  (Jacques Garrigue and Takafumi Saikawa,
   review by Florian Angeletti and Gabriel Radanne)

- #10358: Use a hash table for the load path.
  (Leo White, review by Gabriel Scherer)

- #8936: Per-function environment for Emit
  (Greta Yorsh, review by Vincent Laviron and Florian Angeletti)

- #10543: Fix Ast_mapper to apply the mapping function to the constants in
  "interval" patterns `c1..c2`.
  (Guillaume Petiot, review by Gabriel Scherer and Nicolás Ojeda Bär)

### Internal typechecker changes:

- #10174: Make Tsubst more robust by avoiding strange workarounds
  (Takafumi Saikawa and Jacques Garrigue, review by Gabriel Scherer and
   Florian Angeletti)

- #10265: Move type_unboxed.unboxed into type_kind
  (Stephen Dolan, review by Gabriel Scherer)

- #10307: Refactor type_description in the typing env
  (Nicolas Chataing, review by Takafumi Saikawa, Florian Angeletti and Thomas
   Refis)

- #10311: Separate the constraint-solving part of Typecore.type_pat into
  specific solver functions.
  (Jacques Garrigue and Takafumi Saikawa, review by Gabriel Scherer)

- #10428: Make build_other_constrs work with names instead of tags.
  (Nicolas Chataing, review by Florian Angeletti)

### Build system:

- #10332, #10333: Generate lambda/runtimedef.ml correctly in Swedish locale.
  (the letter 'w' is not included in '[a-z]' in sv_SE.UTF-8)
  (David Allsopp, report by Anders Jackson, review by Florian Angeletti and
   Gabriel Scherer)

- #10289, #10406: Do not print option documentation in usage messages.
    (Pavlo Khrystenko, review by Gabriel Scherer, fix by Kate Deplaix)

- #9191, #10091, #10182: take the LDFLAGS variable into account, except on
  flexlink-using systems.
  (Gabriel Scherer, review by Sébastien Hinderer and David Allsopp,
   report by Ralph Seichter)

- #10135: Overhaul the FlexDLL bootstrap process. It's now fully integrated
  with the default build target and controlled by --with-flexdll which allows
  externally downloaded sources for FlexDLL to be specified. A separate
  non-shared version of the runtime is built, and shared artefacts are no longer
  built twice. When bootstrapping, any flexlink in PATH is now ignored and the
  Cygwin port also supports bootstrapping FlexDLL. flexlink.opt is automatically
  built and installed as part of opt.opt/world.opt.
  (David Allsopp, review by Sébastien Hinderer)

- #10156: configure script: fix sockets feature detection.
  (Lucas Pluvinage, review by David Allsopp and Damien Doligez)

- #10176, #10632: By default, call the assembler through the C compiler driver
  (Sébastien Hinderer, review by Gabriel Scherer, David Allsopp and Xavier
  Leroy)

- #10186: configure wasn't using library link flags when searching for
  network functions on systems where they're not in libc. Fix IPv6 and
  socklen_t detection on Windows.
  (Antonin Décimo, review by David Allsopp and Sébastien Hinderer)

- #10366: Make it possible to use the OCAMLRUN variable to specify
  which runtime to use while building the compilers (Sébastien Hinderer,
  review by David Allsopp)

- #10451, #10635: Replace the use of iconv with a C utility to convert $(LIBDIR)
  to a C string constant on Windows when building the runtime. Hardens the
  generation of the constant on Unix for paths with backslashes, double-quotes
  and newlines.
  (David Allsopp, review by Florian Angeletti and Sébastien Hinderer)

- #10471: Fix detection of arm32 architectures with musl in configure.
  (Louis Gesbert, review by David Allsopp)

### Bug fixes:

- #6654, #9774, #10401: make `include` and with `constraints` handle correctly
  the ghost components of signatures. For instance, in

    include struct class c = object end end type c

   the type `c` shadows the `class c` to avoid shadowing only the ghost type
   c introduced by the class.
  (Florian Angeletti, report by Eduardo Rafael, review by Gabriel Scherer)

- #6985, #10385: remove all ghost row types from included modules
  (Florian Angeletti, review by Gabriel Scherer)

- #7453, #9828, #10416: fix #show for recursive types and modules
  (Florian Angeletti, review by Gabriel Scherer)

* #7469, #10408: Sys.time now returns processor time on Windows (previously
  returned wall-clock time)
  (David Allsopp, review by Nicolás Ojeda Bär)

* #8857, #10220: Don't clobber GetLastError() in caml_leave_blocking_section
  when the systhreads library is loaded.
  (David Allsopp, report by Anton Bachin, review by Xavier Leroy)

- #8575, #10362: Surprising interaction between polymorphic variants
  and constructor disambiguation.
  (Jacques Garrigue, report and review by Thomas Refis)

- #8917, #8929, #9889, #10219: fix printing of nested recursive definitions
  in presence of a name collision.
  (Florian Angeletti, report by Thomas Refis, review by Gabriel Scherer)

- #10005: Try expanding aliases in Ctype.nondep_type_rec
  (Stephen Dolan, review by Gabriel Scherer, Leo White and Xavier Leroy)

- #10072, #10085: Check that sizes and offsets in stack frame descriptors
  do not overflow the 16-bit fields where they are stored.
  (Xavier Leroy, report by Github user pveber, review by Gabriel Scherer)

- #10087, #10138: In the toplevel REPL, don't use the cache
  of included directories, so that files created or deleted while
  the REPL is running are correctly handled.
  (Xavier Leroy, report by Github user quakerquickoats, review by
   Jeremie Dimino)

- #10294, #10295: fix an assert-failure in pattern-matching compilation
  (Gabriel Scherer, review by Thomas Refis and Luc Maranget,
   report by Nicolás Ojeda Bär)

- #10147, #10148: Fix building runtime with GCC on macOS.
  (David Allsopp, report by John Skaller)

- #10166: Fix illegal permutation error reporting in module aliases.
  (Matthew Ryan, review by Florian Angeletti)

- #10189, #10190, #10347: Universal variables leaking through GADT equations
  (Jacques Garrigue, report and review by Leo White)

- #10205: Avoid overwriting closures while initialising recursive modules
  (Stephen Dolan, review by Xavier Leroy, Hugo Heuzard and Vincent Laviron)

- #10253, #10373: tweak error message for unknown variant constructors
  or record fields in type-directed disambiguation
  (Florian Angeletti, report by Hongbo Zhang, review by Gabriel Scherer)

* #10277, #10383: Need to detect ambiguity recursively inside types to
  guarantee principality (affects only principal mode)
  (Jacques Garrigue, review by Thomas Refis, Leo White and Kate Deplaix)

- #10283, #10284: Enforce right-to-left evaluation order for Lstaticraise
  (Vincent Laviron, report by Github user Ngoguey42, review by Gabriel Scherer)

- #10298, #10305: Incorrect propagation of type equalities in functor
  application
  (Jacques Garrigue, report and review by Didier Remy)

- #10324, #10325: Prevent generation of Lsend(Cached, _) in bytecode
  (Vincent Laviron, report by Yawar Amin and Nicolás Ojeda Bär, review by
   Jacques Garrigue)

- #10338, #10340: Translcore.push_defaults does not respect scoping
  (Jacques Garrigue, report and review by Stephen Dolan)

- #10351: Fix DLL loading with binutils 2.36+ on mingw-w64
  (David Allsopp, review by Nicolás Ojeda Bär)

- #10339, #10354, #10387: Fix handling of exception-raising specific
  operations during spilling and liveness analysis.
  (This bug affects ARM and ARM64.)
  In passing, refactor Proc.op_is_pure and Mach.operation_can_raise.
  (Xavier Leroy, report by Richard Bornat, review by Stephen Dolan
   and Mark Shinwell)

- #10371: Stop generating useless `.cds` file when using
  `-output-complete-exe`.
  (Nicolás Ojeda Bär, review by David Allsopp)

- #10376: Link runtime libraries correctly on msvc64 in -output-complete-obj
  (David Allsopp, review by Gabriel Scherer)

- #10380: Correct handling of UTF-8 paths in configure on Windows
  (David Allsopp, review by Sébastien Hinderer)

- #10450, #10558: keep %apply and %revapply primitives working with abstract
  types. This breach of backward compatibility was only present in the alpha
  releases of OCaml 4.13.0 .
  (Florian Angeletti, review by Thomas Refis and Leo White)

- #10454: Check row_more in nondep_type_rec.
  (Leo White, review by Thomas Refis)

- #10468: Correctly pretty print local type substitution, e.g. type t := ...,
  with -dsource
  (Matt Else, review by Florian Angeletti)

- #10461, #10498: `caml_send*` helper functions take derived pointers
  as arguments.  Those must be declared with type Addr instead of Val.
  Moreover, poll point insertion must be disabled for `caml_send*`,
  otherwise the derived pointer is live across a poll point.
  (Vincent Laviron and Xavier Leroy, review by Xavier Leroy and Sadiq Jaffer)

- #10511: Cygwin ports now correctly configure when flexdll is not available.
  (David Allsopp, review by Florian Angeletti)

- #10550, #10551: fix pretty-print of gadt-pattern-with-type-vars
  (Chet Murthy, review by Gabriel Scherer)

- #10584, #10856: Standard Library documentation build no longer fails if
  optional libraries have been disabled.
  (David Allsopp, report by Yuri Victorovich, review by Florian Angeletti)

- #10593: Fix untyping of patterns without named existential quantifiers. This
  bug was only present in the beta version of OCaml 4.13.0.
  (Ulysse Gérard, review by Florian Angeletti)

- #10603, #10611: Fix if condition marked as inconstant in flambda
  (Vincent Laviron and Pierre Chambart, report by Marcello Seri)


OCaml 4.12, maintenance version
-------------------------------

### Bug fixes:

- #10442, #10446: Fix regression in the toplevel to #directory caused by
  corrections and improvements to the Load_path in #9611. #directory now
  adds the path to the start of the load path again (so files in the newly
  added directory take priority).
  (David Allsopp, report by Vasile Rotaru, review by Florian Angeletti
   and Nicolás Ojeda Bär)

- #10478: Fix segfault under Windows due to a mistaken initialization of thread
  ID when a thread starts.
  (David Allsopp, Nicolás Ojeda Bär, review by Xavier Leroy)

- #10626, #10628: Wrong reloading of the x86-64 instruction for
  integer multiplication by a constant, causing the assembler to
  reject the ocamlopt-generated code.
  (Xavier Leroy, report by Dave Aitken, review by Vincent Laviron)

OCaml 4.12.0 (24 February 2021)
-------------------------------

### Supported platforms (highlights):

- #9699: add support for iOS and macOS on ARM 64 bits
  (Eduardo Rafael, review by Xavier Leroy, Nicolás Ojeda Bär
   and Anil Madhavapeddy, additional testing by Michael Schmidt)

### Standard library (highlights):

- #9797: Add Sys.mkdir and Sys.rmdir.
  (David Allsopp, review by Nicolás Ojeda Bär, Sébastien Hinderer and
   Xavier Leroy)

* #9765: add init functions to Bigarray.
  (Jeremy Yallop, review by Gabriel Scherer, Nicolás Ojeda Bär, and
   Xavier Leroy)

* #9668: List.equal, List.compare
  (This could break code using "open List" by shadowing
   Stdlib.{equal,compare}.)
  (Gabriel Scherer, review by Nicolás Ojeda Bär, Daniel Bünzli and Alain Frisch)

- #9066: a new Either module with
  type 'a Either.t = Left of 'a | Right of 'b
  (Gabriel Scherer, review by Daniel Bünzli, Thomas Refis, Jeremy Yallop)

- #9066: List.partition_map :
    ('a -> ('b, 'c) Either.t) -> 'a list -> 'b list * 'c list
  (Gabriel Scherer, review by Jeremy Yallop)

- #9865: add Format.pp_print_seq
  (Raphaël Proust, review by Nicolás Ojeda Bär)

### Compiler user-interface and warnings (highlights):

- #9657: Warnings can now be referred to by their mnemonic name. The names are
  displayed using `-warn-help` and can be utilized anywhere where a warning list
  specification is expected.
      ocamlc -w +fragile-match
      ...[@@ocaml.warning "-fragile-match"]
  Note that only a single warning name at a time is supported for now:
  "-w +foo-bar" does not work, you must use "-w +foo -w -bar".
  (Nicolás Ojeda Bär, review by Gabriel Scherer, Florian Angeletti and
   Leo White)

- #8939: Command-line option to save Linear IR before emit.
  (Greta Yorsh, review by Mark Shinwell, Sébastien Hinderer and Frédéric Bour)

- #9003: Start compilation from Emit when the input file is in Linear IR format.
  (Greta Yorsh, review by Jérémie Dimino, Gabriel Scherer and Frédéric Bour)

### Language features (highlights):

* #9500, #9727, #9866, #9870, #9873: Injectivity annotations
  One can now mark type parameters as injective, which is useful for
  abstract types:
    module Vec : sig type !'a t end = struct type 'a t = 'a array end
  On non-abstract types, this can be used to check the injectivity of
  parameters. Since all parameters of record and sum types are by definition
  injective, this only makes sense for type abbreviations:
    type !'a t = 'a list
  Note that this change required making the regularity check stricter.
  (Jacques Garrigue, review by Jeremy Yallop and Leo White)

### Runtime system (highlights):

- #9534, #9947: Introduce a naked pointers checker mode to the runtime
  (configure option --enable-naked-pointers-checker).  Alarms are printed
  when the garbage collector finds out-of-heap pointers that could
  cause a crash in no-naked-pointers mode.
  (Enguerrand Decorne, KC Sivaramakrishnan, Xavier Leroy, Stephen Dolan,
  David Allsopp, Nicolás Ojeda Bär review by Xavier Leroy, Nicolás Ojeda Bär)

* #1128, #7503, #9036, #9722, #10069: EINTR-based signal handling.
  When a signal arrives, avoid running its OCaml handler in the middle
  of a blocking section. Instead, allow control to return quickly to
  a polling point where the signal handler can safely run, ensuring that
  I/O locks are not held while it runs. A polling point was removed from
  caml_leave_blocking_section, and one added to caml_raise.
  (Stephen Dolan, review by Goswin von Brederlow, Xavier Leroy, Damien
   Doligez, Anil Madhavapeddy, Guillaume Munch-Maccagnoni
   and Jacques-Henri Jourdan)

* #5154, #9569, #9734: Add `Val_none`, `Some_val`, `Is_none`, `Is_some`,
  `caml_alloc_some`, and `Tag_some`. As these macros are sometimes defined by
  authors of C bindings, this change may cause warnings/errors in case of
  redefinition.
  (Nicolás Ojeda Bär, review by Stephen Dolan, Gabriel Scherer, Mark Shinwell,
  and Xavier Leroy)

* #9674: Memprof: guarantee that an allocation callback is always run
  in the same thread the allocation takes place
  (Jacques-Henri Jourdan, review by Stephen Dolan)

- #10025: Track custom blocks (e.g. Bigarray) with Memprof
  (Stephen Dolan, review by Leo White, Gabriel Scherer and Jacques-Henri
   Jourdan)

- #9619: Change representation of function closures so that code pointers
  can be easily distinguished from environment variables
  (Xavier Leroy, review by Mark Shinwell and Damien Doligez)

- #9654: More efficient management of code fragments.
  (Xavier Leroy, review by Jacques-Henri Jourdan, Damien Doligez, and
  Stephen Dolan)

### Other libraries (highlights):

- #9573: reimplement Unix.create_process and related functions without
  Unix.fork, for better efficiency and compatibility with threads.
  (Xavier Leroy, review by Gabriel Scherer and Anil Madhavapeddy)

- #9575: Add Unix.is_inet6_addr
  (Nicolás Ojeda Bär, review by Xavier Leroy)

- #9930: new module Semaphore in the thread library, implementing
  counting semaphores and binary semaphores
  (Xavier Leroy, review by Daniel Bünzli and Damien Doligez,
   additional suggestions by Stephen Dolan and Craig Ferguson)

* #9206, #9419: update documentation of the threads library;
  deprecate Thread.kill, Thread.wait_read, Thread.wait_write,
  and the whole ThreadUnix module.
  (Xavier Leroy, review by Florian Angeletti, Guillaume Munch-Maccagnoni,
   and Gabriel Scherer)

### Manual and documentation (highlights):

- #9755: Manual: post-processing the html generated by ocamldoc and
   hevea. Improvements on design and navigation, including a mobile
   version, and a quick-search functionality for the API.
   (San Vũ Ngọc, review by David Allsopp and Florian Angeletti)

- #9468: HACKING.adoc: using dune to get merlin support
  (Thomas Refis, review by Gabriel Scherer)

- #9684: document in address_class.h the runtime value model in
  naked-pointers and no-naked-pointers mode
  (Xavier Leroy and Gabriel Scherer)

### Internal/compiler-libs changes (highlights):

- #9464, #9493, #9520, #9563, #9599, #9608, #9647: refactor
  the pattern-matching compiler
  (Thomas Refis and Gabriel Scherer, review by Florian Angeletti)

- #9696: ocamltest now shows its log when a test fails. In addition, the log
  contains the output of executed programs.
  (Nicolás Ojeda Bär, review by David Allsopp, Sébastien Hinderer and Gabriel
  Scherer)

### Build system (highlights):

- #9824, #9837: Honour the CFLAGS and CPPFLAGS variables.
  (Sébastien Hinderer, review by David Allsopp)

- #10063: (Re-)enable building on illumos (SmartOS, OmniOS, ...) and
  Oracle Solaris; x86_64/GCC and 64-bit SPARC/Sun PRO C compilers.
  (partially revert #2024).
  (Tõivo Leedjärv and Konstantin Romanov,
   review by Gabriel Scherer, Sébastien Hinderer and Xavier Leroy)


### Language features:

- #1655: pattern aliases do not ignore type constraints
  (Thomas Refis, review by Jacques Garrigue and Gabriel Scherer)

- #9429: Add unary operators containing `#` to the parser for use in ppx
  rewriters
  (Leo White, review by Damien Doligez)

### Runtime system:

* #9697: Remove the Is_in_code_area macro and the registration of DLL code
  areas in the page table, subsumed by the new code fragment management API
  (Xavier Leroy, review by Jacques-Henri Jourdan)

- #9756: garbage collector colors change
  removes the gray color from the major gc
  (Sadiq Jaffer and Stephen Dolan reviewed by Xavier Leroy,
  KC Sivaramakrishnan, Damien Doligez and Jacques-Henri Jourdan)

* #9513: Selectively initialise blocks in `Obj.new_block`. Reject `Custom_tag`
  objects and zero-length `String_tag` objects.
  (KC Sivaramakrishnan, review by David Allsopp, Xavier Leroy, Mark Shinwell
  and Leo White)

- #9564: Add a macro to construct out-of-heap block header.
  (KC Sivaramakrishnan, review by Stephen Dolan, Gabriel Scherer,
   and Xavier Leroy)

- #9951: Ensure that the mark stack push optimisation handles naked pointers
  (KC Sivaramakrishnan, reported by Enguerrand Decorne, review by Gabriel
   Scherer, and Xavier Leroy)

- #9678: Reimplement `Obj.reachable_words` using a hash table to
  detect sharing, instead of temporary in-place modifications.  This
  is a prerequisite for Multicore OCaml.
  (Xavier Leroy, review by Jacques-Henri Jourdan and Sébastien Hinderer)

- #1795, #9543: modernize signal handling on Linux i386, PowerPC, and s390x,
  adding support for Musl ppc64le along the way.
  (Xavier Leroy and Anil Madhavapeddy, review by Stephen Dolan)

- #9648, #9689: Update the generic hash function to take advantage
  of the new representation for function closures
  (Xavier Leroy, review by Stephen Dolan)

- #9649: Update the marshaler (output_value) to take advantage
  of the new representation for function closures
  (Xavier Leroy, review by Damien Doligez)

- #10050: update {PUSH,}OFFSETCLOSURE* bytecode instructions to match new
  representation for closures
  (Nathanaëlle Courant, review by Xavier Leroy)

- #9728: Take advantage of the new closure representation to simplify the
  compaction algorithm and remove its dependence on the page table
  (Damien Doligez, review by Jacques-Henri Jourdan and Xavier Leroy)

- #2195: Improve error message in bytecode stack trace printing and load
  debug information during bytecode startup if OCAMLRUNPARAM=b=2.
  (David Allsopp, review by Gabriel Scherer and Xavier Leroy)

- #9466: Memprof: optimize random samples generation.
  (Jacques-Henri Jourdan, review by Xavier Leroy and Stephen Dolan)

- #9628: Memprof: disable sampling when memprof is suspended.
  (Jacques-Henri Jourdan, review by Gabriel Scherer and Stephen Dolan)

- #10056: Memprof: ensure young_trigger is within the bounds of the minor
  heap in caml_memprof_renew_minor_sample (regression from #8684)
  (David Allsopp, review by Guillaume Munch-Maccagnoni and
  Jacques-Henri Jourdan)

- #9506: Remove support for FreeBSD prior to 4.0R, that required explicit
  floating-point initialization to behave like IEEE standard
  (Hannes Mehnert, review by David Allsopp)

- #8807, #9503: Use different symbols for do_local_roots on bytecode and native
  (Stephen Dolan, review by David Allsopp and Xavier Leroy)

- #9670: Report full major collections in Gc stats.
  (Leo White, review by Gabriel Scherer)

- #9675: Remove the caml_static_{alloc,free,resize} primitives, now unused.
  (Xavier Leroy, review by Gabriel Scherer)

- #9710: Drop "support" for an hypothetical JIT for OCaml bytecode
   which has never existed.
  (Jacques-Henri Jourdan, review by Xavier Leroy)

- #9742, #9989: Ephemerons are now compatible with infix pointers occurring
   when using mutually recursive functions.
   (Jacques-Henri Jourdan, review by François Bobot)

- #9888, #9890: Fixes a bug in the `riscv` backend where register t0 was not
  saved/restored when performing a GC. This could potentially lead to a
  segfault.
  (Nicolás Ojeda Bär, report by Xavier Leroy, review by Xavier Leroy)

- #9907: Fix native toplevel on native Windows.
  (David Allsopp, review by Florian Angeletti)

- #9909: Remove caml_code_area_start and caml_code_area_end globals (no longer
  needed as the pagetable heads towards retirement).
  (David Allsopp, review by Xavier Leroy)

- #9949: Clarify documentation of GC message 0x1 and make sure it is
  displayed every time a major cycle is forcibly finished.
  (Damien Doligez, review by Xavier Leroy)

- #10062: set ARCH_INT64_PRINTF_FORMAT correctly for both modes of mingw-w64
  (David Allsopp, review by Xavier Leroy)

### Code generation and optimizations:

- #9551: ocamlc no longer loads DLLs at link time to check that
  external functions referenced from OCaml code are defined.
  Instead, .so/.dll files are parsed directly by pure OCaml code.
  (Nicolás Ojeda Bär, review by Daniel Bünzli, Gabriel Scherer,
   Anil Madhavapeddy, and Xavier Leroy)

- #9620: Limit the number of parameters for an uncurried or untupled
   function.  Functions with more parameters than that are left
   partially curried or tupled.
   (Xavier Leroy, review by Mark Shinwell)

- #9752: Revised handling of calling conventions for external C functions.
   Provide a more precise description of the types of unboxed arguments,
   so that the ARM64 iOS/macOS calling conventions can be honored.
   (Xavier Leroy, review by Mark Shinwell and Eduardo Rafael)

- #9838: Ensure that Cmm immediates are generated as Cconst_int where
  possible, improving instruction selection.
  (Stephen Dolan, review by Leo White and Xavier Leroy)

- #9864: Revised recognition of immediate arguments to integer operations.
  Fixes several issues that could have led to producing assembly code
  that is rejected by the assembler.
  (Xavier Leroy, review by Stephen Dolan)

- #9969, #9981: Added mergeable flag to ELF sections containing mergeable
  constants.  Fixes compatibility with the integrated assembler in clang 11.0.0.
  (Jacob Young, review by Nicolás Ojeda Bär)

### Standard library:

- #9781: add injectivity annotations to parameterized abstract types
  (Jeremy Yallop, review by Nicolás Ojeda Bär)

* #9554: add primitive __FUNCTION__ that returns the name of the current method
  or function, including any enclosing module or class.
  (Nicolás Ojeda Bär, Stephen Dolan, review by Stephen Dolan)

- #9075: define to_rev_seq in Set and Map modules.
  (Sébastien Briais, review by Gabriel Scherer and Nicolás Ojeda Bär)

- #9561: Unbox Unix.gettimeofday and Unix.time
  (Stephen Dolan, review by David Allsopp)

- #9570: Provide an Atomic module with a trivial purely-sequential
  implementation, to help write code that is compatible with Multicore
  OCaml.
  (Gabriel Scherer, review by Xavier Leroy)

- #10035: Make sure that flambda respects atomicity in the Atomic module.
  (Guillaume Munch-Maccagnoni, review by Gabriel Scherer)

- #9571: Make at_exit and Printexc.register_printer thread-safe.
  (Guillaume Munch-Maccagnoni, review by Gabriel Scherer and Xavier Leroy)

- #9587: Arg: new Rest_all spec to get all rest arguments in a list
  (this is similar to Rest, but makes it possible to detect when there
   are no arguments (an empty list) after the rest marker)
  (Gabriel Scherer, review by Nicolás Ojeda Bär and David Allsopp)

- #9655: Obj: introduce type raw_data and functions raw_field, set_raw_field
   to manipulate out-of-heap pointers in no-naked-pointer mode,
   and more generally all other data that is not a well-formed OCaml value
   (Xavier Leroy, review by Damien Doligez and Gabriel Scherer)

- #9663: Extend Printexc API for raw backtrace entries.
  (Stephen Dolan, review by Nicolás Ojeda Bär and Gabriel Scherer)

- #9763: Add function Hashtbl.rebuild to convert from old hash table
  formats (that may have been saved to persistent storage) to the
  current hash table format.  Remove leftover support for the hash
  table format and generic hash function that were in use before OCaml 4.00.
  (Xavier Leroy, review by Nicolás Ojeda Bär)

- #10070: Fix Float.Array.blit when source and destination arrays coincide.
  (Nicolás Ojeda Bär, review by Alain Frisch and Xavier Leroy)

### Other libraries:

- #8796: On Windows, make Unix.utimes use FILE_FLAG_BACKUP_SEMANTICS flag
  to allow it to work with directories.
  (Daniil Baturin, review by Damien Doligez)

- #9593: Use new flag for non-elevated symbolic links and test for Developer
  Mode on Windows
  (Manuel Hornung, review by David Allsopp and Nicolás Ojeda Bär)

* #9601: Return EPERM for EUNKNOWN -1314 in win32unix (principally affects
  error handling when Unix.symlink is unavailable)
  (David Allsopp, review by Xavier Leroy)

- #9338, #9790: Dynlink: make sure *_units () functions report accurate
  information before the first load.
  (Daniel Bünzli, review by Xavier Leroy and Nicolás Ojeda Bär)

* #9757, #9846, #10161: check proper ownership when operating over mutexes.
  Now, unlocking a mutex held by another thread or not locked at all
  reliably raises a Sys_error exception.  Before, it was undefined
  behavior, but the documentation did not say so.
  Likewise, locking a mutex already locked by the current thread
  reliably raises a Sys_error exception.  Before, it could
  deadlock or succeed (and do recursive locking), depending on the OS.
  (Xavier Leroy, report by Guillaume Munch-Maccagnoni, review by
  Guillaume Munch-Maccagnoni, David Allsopp, and Stephen Dolan)

- #9802: Ensure signals are handled before Unix.kill returns
  (Stephen Dolan, review by Jacques-Henri Jourdan)

- #9869, #10073: Add Unix.SO_REUSEPORT
  (Yishuai Li, review by Xavier Leroy, amended by David Allsopp)

- #9906, #9914: Add Unix._exit as a way to exit the process immediately,
  skipping any finalization action
  (Ivan Gotovchits and Xavier Leroy, review by Sébastien Hinderer and
   David Allsopp)

- #9958: Raise exception in case of error in Unix.setsid.
  (Nicolás Ojeda Bär, review by Stephen Dolan)

- #9971, #9973: Make sure the process can terminate when the last thread
  calls Thread.exit.
  (Xavier Leroy, report by Jacques-Henri Jourdan, review by David Allsopp
  and Jacques-Henri Jourdan).

### Tools:

- #9551: ocamlobjinfo is now able to display information on .cmxs shared
  libraries natively; it no longer requires libbfd to do so
  (Nicolás Ojeda Bär, review by Daniel Bünzli, Gabriel Scherer,
   Anil Madhavapeddy, and Xavier Leroy)

* #9299, #9795: ocamldep: do not process files during cli parsing. Fixes
  various broken cli behaviours.
  (Daniel Bünzli, review by Nicolás Ojeda Bär)

### Debugging and profiling:

- #9606, #9635, #9637: fix 4.10 performance regression in the debugger
  (behaviors quadratic in the size of the debugged program)
  (Xavier Leroy, report by Jacques Garrigue and Virgile Prevosto,
  review by David Allsopp and Jacques-Henri Jourdan)

- #9948: Remove Spacetime.
  (Nicolás Ojeda Bär, review by Stephen Dolan and Xavier Leroy)

### Manual and documentation:

- #10142, #10154: improved rendering and latex code for toplevel code examples.
  (Florian Angeletti, report by John Whitington, review by Gabriel Scherer)

- #9745: Manual: Standard Library labeled and unlabeled documentation unified
  (John Whitington, review by Nicolás Ojeda Bär, David Allsopp,
   Thomas Refis, and Florian Angeletti)

- #9877: manual, warn that multi-index indexing operators should be defined in
  conjunction of single-index ones.
  (Florian Angeletti, review by Hezekiah M. Carty, Gabriel Scherer,
   and Marcello Seri)

- #10233: Document `-save-ir-after scheduling` and update `-stop-after` options.
  (Greta Yorsh, review by Gabriel Scherer and Florian Angeletti)

### Compiler user-interface and warnings:

- #1931: rely on levels to enforce principality in patterns
  (Thomas Refis and Leo White, review by Jacques Garrigue)

* #9011: Do not create .a/.lib files when creating a .cmxa with no modules.
  macOS ar doesn't support creating empty .a files (#1094) and MSVC doesn't
  permit .lib files to contain no objects. When linking with a .cmxa containing
  no modules, it is now not an error for there to be no .a/.lib file.
  (David Allsopp, review by Xavier Leroy)

- #9560: Report partial application warnings on type errors in applications.
  (Stephen Dolan, report and testcase by whitequark, review by Gabriel Scherer
   and Thomas Refis)

- #9583: when bytecode linking fails due to an unavailable module, the module
  that requires it is now included in the error message.
  (Nicolás Ojeda Bär, review by Vincent Laviron)

- #9615: Attach package type attributes to core_type.
  When parsing constraints on a first class module, attributes found after the
  module type were parsed but ignored. Now they are attached to the
  corresponding core_type.
  (Etienne Millon, review by Thomas Refis)

- #6633, #9673: Add hint when a module is used instead of a module type or
  when a module type is used instead of a module or when a class type is used
  instead of a class.
  (Xavier Van de Woestyne, report by whitequark, review by Florian Angeletti
  and Gabriel Scherer)

- #9754: allow [@tailcall true] (equivalent to [@tailcall]) and
  [@tailcall false] (warns if on a tailcall)
  (Gabriel Scherer, review by Nicolás Ojeda Bär)

- #9751: Add warning 68. Pattern-matching depending on mutable state
  prevents the remaining arguments from being uncurried.
  (Hugo Heuzard, review by Leo White)

- #9783: Widen warning 16 (Unerasable optional argument) to more cases.
  (Leo White, review by Florian Angeletti)

- #10008: Improve error message for aliases to the current compilation unit.
  (Leo White, review by Gabriel Scherer)

- #10046: Link all DLLs with -static-libgcc on mingw32 to prevent dependency
  on libgcc_s_sjlj-1.dll with mingw-w64 runtime 8.0.0 (previously this was
  only needed for dllunix.dll).
  (David Allsopp, report by Andreas Hauptmann, review by Xavier Leroy)

- #9634: Allow initial and repeated commas in `OCAMLRUNPARAM`.
  (Nicolás Ojeda Bär, review by Gabriel Scherer)

### Internal/compiler-libs changes:

- #8987: Make some locations more accurate
  (Thomas Refis, review by Gabriel Scherer)

- #9216: add Lambda.duplicate which refreshes bound identifiers
  (Gabriel Scherer, review by Pierre Chambart and Vincent Laviron)

- #9376: Remove spurious Ptop_defs from #use
  (Leo White, review by Damien Doligez)

- #9604: refactoring of the ocamltest codebase.
  (Nicolás Ojeda Bär, review by Gabriel Scherer and Sébastien Hinderer)

- #9498, #9511: make the pattern-matching analyzer more robust to
  or-pattern explosion, by stopping after the first counter-example to
  exhaustivity
  (Gabriel Scherer, review by Luc Maranget, Thomas Refis and Florian Angeletti,
   report by Alex Fedoseev through Hongbo Zhang)

- #9514: optimize pattern-matching exhaustivity analysis in the single-row case
  (Gabriel Scherer, review by Stephen Dolan)

- #9442: refactor the implementation of the [@tailcall] attribute
  to allow for a structured attribute payload
  (Gabriel Scherer, review by Vladimir Keleshev and Nicolás Ojeda Bär)

- #9688: Expose the main entrypoint in compilerlibs
  (Stephen Dolan, review by Nicolás Ojeda Bär, Greta Yorsh and David Allsopp)

- #9715: recheck scope escapes after normalising paths
  (Matthew Ryan, review by Gabriel Scherer and Thomas Refis)

- #9778: Fix printing for bindings where polymorphic type annotations and
  attributes are present.
  (Matthew Ryan, review by Nicolás Ojeda Bär)

- #9797, #9849: Eliminate the routine use of external commands in ocamltest.
  ocamltest no longer calls the mkdir, rm and ln external commands (at present,
  the only external command ocamltest uses is diff).
  (David Allsopp, review by Nicolás Ojeda Bär, Sébastien Hinderer and
   Xavier Leroy)

- #9801: Don't ignore EOL-at-EOF differences in ocamltest.
  (David Allsopp, review by Damien Doligez, much input and thought from
   Daniel Bünzli, Damien Doligez, Sébastien Hinderer, and Xavier Leroy)

- #9889: more caching when printing types with -short-path.
  (Florian Angeletti, review by Gabriel Scherer)

-  #9591: fix pprint of polyvariants that start with a core_type, closed,
   not low (Chet Murthy, review by Florian Angeletti)

-  #9590: fix pprint of extension constructors (and exceptions) that rebind
   (Chet Murthy, review by Florian Angeletti)

- #9963: Centralized tracking of frontend's global state
  (Frédéric Bour and Thomas Refis, review by Gabriel Scherer)

- #9631: Named text sections for caml_system__code_begin/end symbols
  (Greta Yorsh, review by Frédéric Bour)

- #9896: Share the strings representing scopes, fixing some regression
  on .cmo/.cma sizes
  (Alain Frisch and Xavier Clerc, review by Gabriel Scherer)

### Build system:

- #9332, #9518, #9529: Cease storing C dependencies in the codebase. C
  dependencies are generated on-the-fly in development mode. For incremental
  compilation, the MSVC ports require GCC to be present.
  (David Allsopp, review by Sébastien Hinderer, YAML-fu by Stephen Dolan)

- #7121, #9558: Always have the autoconf-discovered ld in PACKLD, with
  extra flags in new variable PACKLD_FLAGS. For
  cross-compilation, this means the triplet-prefixed version will always be
  used.
  (David Allsopp, report by Adrian Nader, review by Sébastien Hinderer)

- #9527: stop including configuration when running 'clean' rules
  to avoid C dependency recomputation.
  (Gabriel Scherer, review by David Allsopp)

- #9804: Build C stubs of libraries in otherlibs/ with debug info.
  (Stephen Dolan, review by Sébastien Hinderer and David Allsopp)

- #9938, #9939: Define __USE_MINGW_ANSI_STDIO=0 for the mingw-w64 ports to
  prevent their C99-compliant snprintf conflicting with ours.
  (David Allsopp, report by Michael Soegtrop, review by Xavier Leroy)

- #9895, #9523: Avoid conflict with C++20 by not installing VERSION to the OCaml
  Standard Library directory.
  (Bernhard Schommer, review by David Allsopp)

- #10044: Always report the detected ARCH, MODEL and SYSTEM, even for bytecode-
  only builds (fixes a "configuration regression" from 4.08 for the Windows
  builds)
  (David Allsopp, review by Xavier Leroy)

- #10071: Fix bug in tests/misc/weaklifetime.ml that was reported in #10055
  (Damien Doligez and Gabriel Scherer, report by David Allsopp)

### Bug fixes:

- #7538, #9669: Check for misplaced attributes on module aliases
  (Leo White, report by Thomas Leonard, review by Florian Angeletti)

- #7813, #9955: make sure the major GC cycle doesn't get stuck in Idle state
  (Damien Doligez, report by Anders Fugmann, review by Jacques-Henri Jourdan)

- #7902, #9556: Type-checker infers recursive type, even though -rectypes is
  off.
  (Jacques Garrigue, report by François Pottier, review by Leo White)

- #8746: Hashtbl: Restore ongoing traversal status after filter_map_inplace
  (Mehdi Bouaziz, review by Alain Frisch)

- #8747, #9709: incorrect principality warning on functional updates of records
  (Jacques Garrigue, report and review by Thomas Refis)

* #8907, #9878: `Typemod.normalize_signature` uses wrong environment
  (Jacques Garrigue, report and review by Leo White)

- #9421, #9427: fix printing of (::) in ocamldoc
  (Florian Angeletti, report by Yawar Amin, review by Damien Doligez)

- #9440: for a type extension constructor with parameterised arguments,
  REPL displayed <poly> for each as opposed to the concrete values used.
  (Christian Quinn, review by Gabriel Scherer)

- #9433: Fix package constraints for module aliases
  (Leo White, review by Jacques Garrigue)

- #9469: Better backtraces for lazy values
  (Leo White, review by Nicolás Ojeda Bär)

- #9521, #9522: correctly fail when comparing functions
  with Closure and Infix tags.
  (Gabriel Scherer and Jeremy Yallop and Xavier Leroy,
   report by Twitter user @st_toHKR through Jun Furuse)

- #9611: maintain order of load path entries in various situations: when passing
  them to system linker, ppx contexts, etc.
  (Nicolás Ojeda Bär, review by Jérémie Dimino and Gabriel Scherer)

- #9633: ocamltest: fix a bug when certain variables set in test scripts would
  be ignored (eg `ocamlrunparam`).
  (Nicolás Ojeda Bär, review by Sébastien Hinderer)

- #9681, #9690, #9693: small runtime changes
  for the new closure representation (#9619)
  (Xavier Leroy, Sadiq Jaffer, Gabriel Scherer,
   review by Xavier Leroy and Jacques-Henri Jourdan)

- #9739, #9747: Avoid calling type variables, types that are not variables in
  recursive occurrence error messages
  (for instance, "Type variable int occurs inside int list")
  (Florian Angeletti, report by Stephen Dolan, review by Armaël Guéneau)

- #9759, #9767: Spurious GADT ambiguity without -principal
  (Jacques Garrigue, report by Thomas Refis,
   review by Thomas Refis and Gabriel Scherer)

- #9799, #9803: make pat_env point to the correct environment
  (Thomas Refis, report by Alex Fedoseev, review by Gabriel Scherer)

- #9825, #9830: the C global variable caml_fl_merge and the C function
  caml_spacetime_my_profinfo (bytecode version) were declared and
  defined with different types.  This is undefined behavior and
  cancause link-time errors with link-time optimization (LTO).
  (Xavier Leroy, report by Richard Jones, review by Nicolás Ojeda Bär)

- #9753: fix build for Android
  (Eduardo Rafael, review by Xavier Leroy)

- #9848, #9855: Fix double free of bytecode in toplevel
  (Stephen Dolan, report by Sampsa Kiiskinen, review by Gabriel Scherer)

- #9858, #9861: Compiler fails with Ctype.Nondep_cannot_erase exception
  (Thomas Refis, report by Philippe Veber, review by Florian Angeletti)

- #9860: wrong range constraint for subtract immediate on zSystems / s390x
  (Xavier Leroy, review by Stephen Dolan)

- #9868, #9872, #9892: bugs in {in,out}_channel_length and seek_in
  for files opened in text mode under Windows
  (Xavier Leroy, report by Alain Frisch, review by Nicolás Ojeda Bär
  and Alain Frisch)

- #9925: Correct passing -fdebug-prefix-map to flexlink on Cygwin by prefixing
  it with -link.
  (David Allsopp, review by Xavier Leroy)

- #9927: Restore Cygwin64 support.
  (David Allsopp, review by Xavier Leroy)

- #9940: Fix unboxing of allocated constants from other compilation units
  (Vincent Laviron, report by Stephen Dolan, review by Xavier Leroy and
  Stephen Dolan)

- #9991: Fix reproducibility for `-no-alias-deps`
  (Leo White, review by Gabriel Scherer and Florian Angeletti)

- #9998: Use Sys.opaque_identity in CamlinternalLazy.force
  This removes extra warning 59 messages when compiling afl-instrumented
  code with flambda -O3.
  (Vincent Laviron, report by Louis Gesbert, review by Gabriel Scherer and
   Pierre Chambart)

- #9999: fix -dsource printing of the pattern (`A as x | (`B as x)).
  (Gabriel Scherer, report by Anton Bachin, review by Florian Angeletti)

- #9970, #10010: fix the declaration scope of extensible-datatype constructors.
  A regression that dates back to 4.08 makes extensible-datatype constructors
  with inline records very fragile, for example:
    type 'a t += X of {x : 'a}
  (Gabriel Scherer, review by Thomas Refis and Leo White,
   report by Nicolás Ojeda Bär)

- #10048: Fix bug with generalized local opens.
  (Leo White, review by Thomas Refis)

- #10106, #10112: some expected-type explanations where forgotten
  after some let-bindings
  (Gabriel Scherer, review by Thomas Refis and Florian Angeletti,
   report by Daniil Baturin)

OCaml 4.11 maintenance branch
-----------------------------

### Bug fixes:

- #9096, #10096: fix a 4.11.0 performance regression in classes/objects
  declared within a function
  (Gabriel Scherer, review by Leo White, report by Sacha Ayoun)

OCaml 4.11.1 (31 August 2020)
-----------------------------

### Bug fixes:

- #9856, #9857: Prevent polymorphic type annotations from generalizing
  weak polymorphic variables.
  (Leo White, review by Jacques Garrigue)

- #9859, #9862: Remove an erroneous assertion when inferred function types
  appear in the right hand side of an explicit :> coercion
  (Florian Angeletti, review by Thomas Refis)

OCaml 4.11.0 (19 August 2020)
-----------------------------

(Changes that can break existing programs are marked with a "*")

### Runtime system:

- #9096: Print function names in backtraces.
  Old output:
  > Called from file "foo.ml", line 16, characters 42-53
  New output:
  > Called from Foo.bar in file "foo.ml", line 16, characters 42-53
  (Stephen Dolan, review by Leo White and Mark Shinwell)

- #9082: The instrumented runtime now records logs in the CTF format.
  A new API is available in the runtime to collect runtime statistics,
  replacing the previous instrumented runtime macros.
  Gc.eventlog_pause and Gc.eventlog_resume were added to allow user to control
  instrumentation in a running program.
  See the manual for more information on how to use this instrumentation mode.
  (Enguerrand Decorne and Stephen Dolan, with help and review from
  David Allsopp, Sébastien Hinderer, review by Anil Madhavapeddy,
  Nicolás Ojeda Bär, Shakthi Kannan, KC Sivaramakrishnan, Gabriel Scherer,
  Guillaume Munch-Maccagnoni, Damien Doligez, Leo White, Daniel Bünzli
  and Xavier Leroy)

- #9230, #9362: Memprof support for native allocations.
  (Jacques-Henri Jourdan and Stephen Dolan, review by Gabriel Scherer)

- #8920, #9238, #9239, #9254, #9458: New API for statistical memory profiling
  in Memprof.Gc. The new version does no longer use ephemerons and allows
  registering callbacks for promotion and deallocation of memory
  blocks.
  The new API no longer gives the block tags to the allocation callback.
  (Stephen Dolan and Jacques-Henri Jourdan, review by Damien Doligez
   and Gabriel Scherer)

- #9353: Reimplement `output_value` and the `Marshal.to_*` functions
  using a hash table to detect sharing, instead of temporary in-place
  modifications.  This is a prerequisite for Multicore OCaml.
  (Xavier Leroy and Basile Clément, review by Gabriel Scherer and
  Stephen Dolan)


- #9119: Make [caml_stat_resize_noexc] compatible with the [realloc]
  API when the old block is NULL.
  (Jacques-Henri Jourdan, review by Xavier Leroy)

- #9233: Restore the bytecode stack after an allocation.
  (Stephen Dolan, review by Gabriel Scherer and Jacques-Henri Jourdan)

- #9249: restore definition of ARCH_ALIGN_INT64 in m.h if the architecture
  requires 64-bit integers to be double-word aligned (autoconf regression)
  (David Allsopp, review by Sébastien Hinderer)

- #9259: Made `Ephemeron.blit_key` and `Weak.blit` faster. They are now
  linear in the size of the range being copied instead of depending on the
  total sizes of the ephemerons or weak arrays involved.
  (Arseniy Alekseyev, design advice by Leo White, review by François Bobot
  and Damien Doligez)

- #9279: Memprof optimisation.
  (Stephen Dolan, review by Jacques-Henri Jourdan)

- #9280: Micro-optimise allocations on amd64 to save a register.
  (Stephen Dolan, review by Xavier Leroy)

- #9426: build the Mingw ports with higher levels of GCC optimization
  (Xavier Leroy, review by Sébastien Hinderer)

* #9483: Remove accidental inclusion of <stdio.h> in <caml/misc.h>
  The only release with the inclusion of stdio.h has been 4.10.0
  (Christopher Zimmermann, review by Xavier Leroy and David Allsopp)

- #9282: Make Cconst_symbol have typ_int to fix no-naked-pointers mode.
  (Stephen Dolan, review by Mark Shinwell, Xavier Leroy and Vincent Laviron)

- #9497: Harmonise behaviour between bytecode and native code for
  recursive module initialisation in one particular case (fixes #9494).
  (Mark Shinwell, David Allsopp, Vincent Laviron, Xavier Leroy,
  Geoff Reedy, original bug report by Arlen Cox)

- #8791: use a variable-length encoding when marshalling bigarray dimensions,
  avoiding overflow.
  (Jeremy Yallop, Stephen Dolan, review by Xavier Leroy)

### Code generation and optimizations:

- #9441: Add RISC-V RV64G native-code backend.
  (Nicolás Ojeda Bär, review by Xavier Leroy and Gabriel Scherer)

- #9316, #9443, #9463, #9782: Use typing information from Clambda
  for mutable Cmm variables.
  (Stephen Dolan, review by Vincent Laviron, Guillaume Bury, Xavier Leroy,
  and Gabriel Scherer; temporary bug report by Richard Jones)

- #8637, #8805, #9247, #9296: Record debug info for each allocation.
  (Stephen Dolan and Jacques-Henri Jourdan, review by Damien Doligez,
   KC Sivaramakrishnan and Xavier Leroy)


- #9193: Make tuple matching optimisation apply to Lswitch and Lstringswitch.
  (Stephen Dolan, review by Thomas Refis and Gabriel Scherer)

- #9392: Visit registers at most once in Coloring.iter_preferred.
  (Stephen Dolan, review by Pierre Chambart and Xavier Leroy)

- #9412: Keep Sys.opaque_identity in Cmm and Mach
  (Stephen Dolan, review by Mark Shinwell and Gabriel Scherer)

- #9549, #9557: Make -flarge-toc the default for PowerPC and introduce
  -fsmall-toc to enable the previous behaviour.
  (David Allsopp, report by Nathaniel Wesley Filardo, review by Xavier Leroy)

### Language features

- #8820, #9166: quoted extensions: {%foo|...|} is lighter syntax for
  [%foo {||}], and {%foo bar|...|bar} for [%foo {bar|...|bar}].
  (Gabriel Radanne, Leo White, Gabriel Scherer and Pieter Goetschalckx,
   request by Bikal Lem)

- #7364, #2188, #9592, #9609: improvement of the unboxability check for types
  with a single constructor. Mutually-recursive type declarations can
  now contain unboxed types. This is based on the paper
    https://arxiv.org/abs/1811.02300
  (Gabriel Scherer and Rodolphe Lepigre,
   review by Jeremy Yallop, Damien Doligez and Frédéric Bour)

- #1154, #1706: spellchecker hints and type-directed disambiguation
  for extensible sum type constructors
  (Florian Angeletti, review by Alain Frisch, Gabriel Radanne, Gabriel Scherer
  and Leo White)


- #6673, #1132, #9617: Relax the handling of explicit polymorphic types.
  This improves error messages in some polymorphic recursive definition,
  and requires less polymorphic annotations in some cases of
  mutually-recursive definitions involving polymorphic recursion.
  (Leo White, review by Jacques Garrigue and Gabriel Scherer)

- #9232: allow any class type paths in #-types,
  For instance, "val f: #F(X).t -> unit" is now allowed.
  (Florian Angeletti, review by Gabriel Scherer, suggestion by Leo White)

### Standard library:

- #9077: Add Seq.cons and Seq.append
  (Sébastien Briais, review by Yawar Amin and Florian Angeletti)

- #9235: Add Array.exists2 and Array.for_all2
  (Bernhard Schommer, review by Armaël Guéneau)

- #9226: Add Seq.unfold.
   (Jeremy Yallop, review by Hezekiah M. Carty, Gabriel Scherer and
   Gabriel Radanne)

- #9059: Added List.filteri function, same as List.filter but
  with the index of the element.
  (Léo Andrès, review by Alain Frisch)

- #8894: Added List.fold_left_map function combining map and fold.
  (Bernhard Schommer, review by Alain Frisch and github user @cfcs)

- #9365: Set.filter_map and Map.filter_map
  (Gabriel Scherer, review by Stephen Dolan and Nicolás Ojeda Bär)


- #9248: Add Printexc.default_uncaught_exception_handler
  (Raphael Sousa Santos, review by Daniel Bünzli)

- #8771: Lexing: add set_position and set_filename to change (fake)
   the initial tracking position of the lexbuf.
   (Konstantin Romanov, Miguel Lumapat, review by Gabriel Scherer,
    Sébastien Hinderer, and David Allsopp)

- #9237: `Format.pp_update_geometry ppf (fun geo -> {geo with ...})`
  for formatter geometry changes that are robust to new geometry fields.
  (Gabriel Scherer, review by Josh Berdine and Florian Angeletti)

- #7110: Added Printf.ikbprintf and Printf.ibprintf
  (Muskan Garg, review by Gabriel Scherer and Florian Angeletti)

- #9266: Install pretty-printer for the exception Fun.Finally_raised.
  (Guillaume Munch-Maccagnoni, review by Daniel Bünzli, Gabriel Radanne,
   and Gabriel Scherer)

### Other libraries:

- #9106: Register printer for Unix_error in win32unix, as in unix.
  (Christopher Zimmermann, review by David Allsopp)

- #9183: Preserve exception backtrace of exceptions raised by top-level phrases
  of dynlinked modules.
  (Nicolás Ojeda Bär, review by Xavier Clerc and Gabriel Scherer)

- #9320, #9550: under Windows, make sure that the Unix.exec* functions
  properly quote their argument lists.
  (Xavier Leroy, report by André Maroneze, review by Nicolás Ojeda Bär
   and David Allsopp)

- #9490, #9505: ensure proper rounding of file times returned by
  Unix.stat, Unix.lstat, Unix.fstat.
  (Xavier Leroy and Guillaume Melquiond, report by David Brown,
   review by Gabriel Scherer and David Allsopp)

### Tools:

- #9283, #9455, #9457: add a new toplevel directive `#use_output "<command>"` to
  run a command and evaluate its output.
  (Jérémie Dimino, review by David Allsopp)


- #6969: Argument -nocwd added to ocamldep
  (Muskan Garg, review by Florian Angeletti)

- #8676, #9594: turn debugger off in programs launched by the program
  being debugged
  (Xavier Leroy, report by Michael Soegtrop, review by Gabriel Scherer)

- #9057: aid debugging the debugger by preserving backtraces of unhandled
  exceptions.
  (David Allsopp, review by Gabriel Scherer)

- #9276: objinfo: cm[x]a print extra C options, objects and dlls in
  the order given on the cli. Follow up to #4949.
  (Daniel Bünzli, review by Gabriel Scherer)

- #463: objinfo: better errors on object files coming
  from a different (older or newer), incompatible compiler version.
  (Gabriel Scherer, review by Gabriel Radanne and Damien Doligez)

* #9197: remove compatibility logic from #244 that was designed to
  synchronize toplevel printing margins with Format.std_formatter,
  but also resulted in unpredictable/fragile changes to formatter
  margins.
  Setting the margins on the desired formatters should now work.
  typically on `Format.std_formatter`.
  Note that there currently is no robust way to do this from the
  toplevel, as applications may redirect toplevel printing. In
  a compiler/toplevel driver, one should instead access
  `Location.formatter_for_warnings`; it is not currently exposed
  to the toplevel.
  (Gabriel Scherer, review by Armaël Guéneau)

- #9207, #9210: fix ocamlyacc to work correctly with up to 255 entry
  points to the grammar.
  (Andreas Abel, review by Xavier Leroy)

- #9482, #9492: use diversions (@file) to work around OS limitations
  on length of Sys.command argument.
  (Xavier Leroy, report by Jérémie Dimino, review by David Allsopp)

### Manual and documentation:

- #9141: beginning of the ocamltest reference manual
  (Sébastien Hinderer, review by Gabriel Scherer and Thomas Refis)

- #9228: Various Map documentation improvements: add missing key argument in
  the 'merge' example; clarify the relationship between input and output keys
  in 'union'; note that find and find_opt return values, not bindings.
  (Jeremy Yallop, review by Gabriel Scherer and Florian Angeletti)

- #9255, #9300: reference chapter, split the expression grammar
  (Florian Angeletti, report by Harrison Ainsworth, review by Gabriel Scherer)

- #9325: documented base case for `List.for_all` and `List.exists`
  (Glenn Slotte, review by Florian Angeletti)

- #9410, #9422: replaced naive fibonacci example with gcd
  (Anukriti Kumar, review by San Vũ Ngọc, Florian Angeletti, Léo Andrès)

- #9541: Add a documentation page for the instrumented runtime;
  additional changes to option names in the instrumented runtime.
  (Enguerrand Decorne, review by Anil Madhavapeddy, Gabriel Scherer,
   Daniel Bünzli, David Allsopp, Florian Angeletti,
   and Sébastien Hinderer)

- #9610: manual, C FFI: naked pointers are deprecated, detail the
  forward-compatible options for handling out-of-heap pointers.
  (Xavier Leroy, review by Mark Shinwell, David Allsopp and Florian Angeletti)

- #9618: clarify the Format documentation on the margin and maximum indentation
  limit
  (Florian Angeletti, review by Josh Berdine)


- #8644: fix formatting comment about @raise in stdlib's mli files
  (Élie Brami, review by David Allsopp)

- #9327, #9401: manual, fix infix attribute examples
  (Florian Angeletti, report by David Cadé, review by Gabriel Scherer)

- #9403: added a description for warning 67 and added a "." at the end of
  warnings for consistency.
  (Muskan Garg, review by Gabriel Scherer and Florian Angeletti)

- #7708, #9580: Ensure Stdlib documentation index refers to Stdlib.
  (Stephen Dolan, review by Florian Angeletti, report by Hannes Mehnert)

### Compiler user-interface and warnings:

- #9712: Update the version format to allow "~".
  The new format is "major.minor[.patchlevel][(+|~)additional-info]",
  for instance "4.12.0~beta1+flambda".
  This is a documentation-only change for the 4.11 branch, the new format
  will be used starting with the 4.12 branch.
  (Florian Angeletti, review by Damien Doligez and Xavier Leroy)

- #1664: make -output-complete-obj link the runtime native c libraries when
  building shared libraries like `-output-obj`.
  (Florian Angeletti, review by Nicolás Ojeda Bär)

- #9349: Support [@inlined hint] attribute.
  (Leo White, review by Stephen Dolan)

- #2141: generate .annot files from cmt data; deprecate -annot.
  (Nicolás Ojeda Bär, review by Alain Frisch, Gabriel Scherer and Damien
  Doligez)


* #7678, #8631: ocamlc -c and ocamlopt -c pass same switches to the C
  compiler when compiling .c files (in particular, this means ocamlopt
  passes -fPIC on systems requiring it for shared library support).
  (David Allsopp, report by Daniel Bünzli, review by Sébastien Hinderer)

- #9074: reworded error message for non-regular structural types
  (Florian Angeletti, review by Jacques Garrigue and Leo White,
   report by Chas Emerick)

- #8938: Extend ocamlopt option "-stop-after" to handle "scheduling" argument.
  (Greta Yorsh, review by Florian Angeletti and Sébastien Hinderer)

- #8945, #9086: Fix toplevel show directive to work with constructors
  (Simon Parry, review by Gabriel Scherer, Jeremy Yallop,
  Alain Frisch, Florian Angeletti)

- #9107: improved error message for exceptions in module signature errors
  (Gabriel Scherer, review by Florian Angeletti)

- #9208: -dno-locations option to hide source locations (and debug events)
  from intermediate-representation dumps (-dfoo).
  (Gabriel Scherer, review by Vincent Laviron)

- #9393: Improve recursive module usage warnings
  (Leo White, review by Thomas Refis)

- #9486: Fix configuration for the Haiku operating system
  (Sylvain Kerjean, review by David Allsopp and Sébastien Hinderer)

### Internal/compiler-libs changes:

- #9021: expose compiler Longident.t parsers
  (Florian Angeletti, review by Gabriel Scherer)

- #9452: Add locations to docstring attributes
  (Leo White, review by Gabriel Scherer)


- #463: a new Misc.Magic_number module for user-friendly parsing
  and validation of OCaml magic numbers.
  (Gabriel Scherer, review by Gabriel Radanne and Damien Doligez)

- #1176: encourage better compatibility with older Microsoft C compilers by
  using GCC's -Wdeclaration-after-statement when available. Introduce
  Caml_inline to stop abuse of the inline keyword on MSVC and to help ensure
  that only static inline is used in the codebase (erroneous instance in
  runtime/win32.c removed).
  (David Allsopp, review by Olivier Andrieu and Xavier Leroy)

- #8934: Stop relying on location to track usage
  (Thomas Refis, review by Gabriel Radanne)

- #8970: separate value patterns (matching on values) from computation patterns
  (matching on the effects of a copmutation) in the typedtree.
  (Gabriel Scherer, review by Jacques Garrigue and Alain Frisch)

- #9060: ensure that Misc.protect_refs preserves backtraces
  (Gabriel Scherer, review by Guillaume Munch-Maccagnoni and David Allsopp)

- #9078: make all compilerlibs/ available to ocamltest.
  (Gabriel Scherer, review by Sébastien Hinderer)

- #9079: typecore/parmatch: refactor ppat_of_type and refine
  the use of backtracking on wildcard patterns
  (Florian Angeletti, Jacques Garrigue, Gabriel Scherer,
   review by Thomas Refis)

- #9081: typedtree, make the pat_env field of pattern data immutable
  (Gabriel Scherer, review by Jacques Garrigue, report by Alain Frisch)

- #9178, #9182, #9196: refactor label-disambiguation (Typecore.NameChoice)
  (Gabriel Scherer, Thomas Refis, Florian Angeletti and Jacques Garrigue,
   reviewing each other without self-loops)

- #9321, #9322, #9359, #9361, #9417, #9447: refactor the
  pattern-matching compiler
  (Thomas Refis and Gabriel Scherer, review by Florian Angeletti)

- #9211, #9215, #9222: fix Makefile dependencies in
  compilerlibs, dynlink, ocamltest.
  (Gabriel Scherer, review by Vincent Laviron and David Allsopp)

- #9275: Short circuit simple inclusion checks
  (Leo White, review by Thomas Refis)

- #9305: Avoid polymorphic compare in Ident
  (Leo White, review by Xavier Leroy and Gabriel Scherer)

- #7927: refactor val_env met_env par_env to class_env
  (Muskan Garg, review by Gabriel Scherer and Florian Angeletti)

- #2324, #9613: Replace the caml_int_compare and caml_float_compare
  (C functions) with primitives.
  (Greta Yorsh, review by Stephen Dolan and Vincent Laviron)

- #9246: Avoid rechecking functor applications
  (Leo White, review by Jacques Garrigue)

- #9402: Remove `sudo:false` from .travis.yml
  (Hikaru Yoshimura)

* #9411: forbid optional arguments reordering with -nolabels
  (Thomas Refis, review by Frédéric Bour and Jacques Garrigue)

- #9414: testsuite, ocamltest: keep test artifacts only on failure.
  Use KEEP_TEST_DIR_ON_SUCCESS=1 to keep all artifacts.
  (Gabriel Scherer, review by Sébastien Hinderer)


### Build system:

- #9250: Add --disable-ocamltest to configure and disable building for
  non-development builds.
  (David Allsopp, review by Sébastien Hinderer)

### Bug fixes:

- #7520, #9547: Odd behaviour of refutation cases with polymorphic variants
  (Jacques Garrigue, report by Leo White, reviews by Gabriel Scherer and Leo)

- #7562, #9456: ocamlopt-generated code crashed on Alpine Linux on
  ppc64le, arm, and i386.  Fixed by turning PIE off for musl-based Linux
  systems except amd64 (x86_64) and s390x.
  (Xavier Leroy, review by Gabriel Scherer)

- #7683, #1499: Fixes one case where the evaluation order in native-code
  may not match the one in bytecode.
  (Nicolás Ojeda Bär, report by Pierre Chambart, review by Gabriel Scherer)

- #7696, #6608: Record expression deleted when all fields specified
  (Jacques Garrigue, report by Jeremy Yallop)

- #7741, #9645: Failure to report escaping type variable
  (Jacques Garrigue, report by Gabriel Radanne, review by Gabriel Scherer)

- #7817, #9546: Unsound inclusion check for polymorphic variant
  (Jacques Garrigue, report by Mikhail Mandrykin, review by Gabriel Scherer)

- #7897, #9537: Fix warning 38 for rebound extension constructors
  (Leo White, review by Florian Angeletti)

- #7917, #9426: Use GCC option -fexcess-precision=standard when available,
  avoiding a problem with x87 excess precision in Float.round.
  (Xavier Leroy, review by Sébastien Hinderer)

- #9011: Allow linking .cmxa files with no units on MSVC by not requiring the
  .lib file to be present.
  (David Allsopp, report by Dmitry Bely, review by Xavier Leroy)

- #9064: Relax the level handling when unifying row fields
  (Leo White, review by Jacques Garrigue)

- #9097: Do not emit references to dead labels introduced by #2321 (spacetime).
  (Greta Yorsh, review by Mark Shinwell)

- #9163: Treat loops properly in un_anf
  (Leo White, review by Mark Shinwell, Pierre Chambart and Vincent Laviron)

- #9189, #9281: fix a conflict with Gentoo build system
  by removing an one-letter Makefile variable.
  (Florian Angeletti, report by Ralph Seichter, review by David Allsopp
   and Damien Doligez)

- #9225: Do not drop bytecode debug info after C calls.
  (Stephen Dolan, review by Gabriel Scherer and Jacques-Henri Jourdan)

- #9231: Make sure a debug event (and the corresponding debug
  information) is inserted after every primitive that can appear in a
  collected call stack, and make sure ocamlc preserves such events
  even if they are at tail position.
  (Jacques-Henri Jourdan, review by Gabriel Scherer)

- #9244: Fix some missing usage warnings
  (Leo White, review by Florian Angeletti)

- #9274, avoid reading cmi file while printing types
  (Florian Angeletti, review by Gabriel Scherer)

- #9307, #9345: reproducible env summaries for reproducible compilation
  (Florian Angeletti, review by Leo White)

- #9309, #9318: Fix exhaustivity checking with empty types
  (Florian Angeletti, Stefan Muenzel and Thomas Refis, review by Gabriel Scherer
  and Thomas Refis)

- #9335: actually have --disable-stdlib-manpages not build the manpages
  (implementation conflicted with #8837 which wasn't picked up in review)
  (David Allsopp, review by Florian Angeletti and Sébastien Hinderer)

- #9343: Re-enable `-short-paths` for some error messages
  (Leo White, review by Florian Angeletti)

- #9355, #9356: ocamldebug, fix a fatal error when printing values
  whose type involves a functor application.
  (Florian Angeletti, review by Gabriel Scherer, report by Cyril Six)

- #9367: Make bytecode and native-code backtraces agree.
  (Stephen Dolan, review by Gabriel Scherer)

- #9375, #9477: add forgotten substitution when compiling anonymous modules
  (Thomas Refis, review by Frédéric Bour, report by Andreas Hauptmann)

- #9384, #9385: Fix copy scope bugs in substitutions
  (Leo White, review by Thomas Refis, report by Nick Roberts)

* #9388: Prohibit signature local types with constraints
  (Leo White, review by Jacques Garrigue)

- #7141, #9389: returns exit_code for better user response on linking_error
  (Anukriti Kumar, review by Gabriel Scherer and Valentin Gatien-Baron)

- #9406, #9409: fix an error with packed module types from missing
  cmis.
  (Florian Angeletti, report by Thomas Leonard, review by Gabriel Radanne
   and Gabriel Scherer)

- #9415: Treat `open struct` as `include struct` in toplevel
  (Leo White, review by Thomas Refis)

- #9416: Avoid warning 58 in flambda ocamlnat
  (Leo White, review by Florian Angeletti)

- #9420: Fix memory leak when `caml_output_value_to_block` raises an exception
  (Xavier Leroy, review by Guillaume Munch-Maccagnoni)

- #9428: Fix truncated exception backtrace for C->OCaml callbacks
  on Power and Z System
  (Xavier Leroy, review by Nicolás Ojeda Bär)

- #9623, #9642: fix typing environments in Typedecl.transl_with_constraint
  (Gabriel Scherer, review by Jacques Garrigue and Leo White,
   report by Hugo Heuzard)

- #9695, #9702: no error when opening an alias to a missing module
  (Jacques Garrigue, report and review by Gabriel Scherer)

- #9714, #9724: Add a terminator to the `caml_domain_state` structure
  to better ensure that members are correctly spaced.
  (Antonin Décimo, review by David Allsopp and Xavier Leroy)

OCaml 4.10 maintenance branch
-----------------------------

### Runtime system:

- #9344, #9368: Disable exception backtraces in bytecode programs
  built with "-output-complete-exe". At the moment, such programs do
  not embed debug information and exception backtraces where causing
  them to crash.
  (Jérémie Dimino, review by Nicolás Ojeda Bär)

### Build system:

- #9531: fix support for the BFD library on FreeBSD
  (Hannes Mehnert, review by Gabriel Scherer and David Allsopp)

### Bug fixes:

- #9068, #9437: ocamlopt -output-complete-obj failure on FreeBSD 12
  (Xavier Leroy, report by Hannes Mehnert, review by Sébastien Hinderer)

- #9165, #9840: Add missing -function-sections flag in Makefiles.
  (Greta Yorsh, review by David Allsopp)

- #9495: fix a bug where bytecode binaries compiled with `-output-complete-exe`
  would not execute `at_exit` hooks at program termination (in particular,
  output channels would not be flushed).
  (Nicolás Ojeda Bär, review by David Allsopp)

- #9714, #9724: Use the C++ alignas keyword when compiling in C++ in MSVC.
  Fixes a bug with MSVC C++ 2015 onwards.
  (Antonin Décimo, review by David Allsopp and Xavier Leroy)

- #9736, #9749: Compaction must start in a heap where all free blocks are
  blue, which was not the case with the best-fit allocator.
  (Damien Doligez, report and review by Leo White)

### Tools:

- #9552: restore ocamloptp build and installation
  (Florian Angeletti, review by David Allsopp and Xavier Leroy)

OCaml 4.10.0 (21 February 2020)
-------------------------------

(Changes that can break existing programs are marked with a "*")

### Language features

- #7757, #1726: multi-indices for extended indexing operators:
  `a.%{0;1;2}` desugars to `( .%{ ;.. } ) a [|0;1;2|]`
  (Florian Angeletti, review by Gabriel Radanne)

* #1859, #9117: enforce safe (immutable) strings by removing
  the -unsafe-string option by default. This can be overridden by
  a configure-time option (available since 4.04 in 2016):
  --disable-force-safe-string since 4.08, -no-force-safe-since
  between 4.07 and 4.04.
  In the force-safe-string mode (now the default), the return type of the
  String_val macro in C stubs is `const char*` instead of
  `char*`. This change may break C FFI code.
  (Kate Deplaix)


- #6662, #8908: allow writing "module _ = E" to ignore module expressions
  (Thomas Refis, review by Gabriel Radanne)

### Runtime system:

- #8809, #9292: Add a best-fit allocator for the major heap; still
  experimental, it should be much better than current allocation
  policies (first-fit and next-fit) for programs with large heaps,
  reducing both GC cost and memory usage.
  This new best-fit is not (yet) the default; set it explicitly with
  OCAMLRUNPARAM="a=2" (or Gc.set from the program). You may also want
  to increase the `space_overhead` parameter of the GC (a percentage,
  80 by default), for example OCAMLRUNPARAM="o=85", for optimal
  speed.
  (Damien Doligez, review by Stephen Dolan, Jacques-Henri Jourdan,
   Xavier Leroy, Leo White)

* #8713, #8940, #9115, #9143, #9202, #9251:
  Introduce a state table in the runtime to contain the global variables.
  (The Multicore runtime will have one such state for each domain.)

   This changes the status of some internal variables of the OCaml runtime;
   in many cases the header file originally defining the internal variable
   provides a compatibility macro with the old name, but programs
   re-defining those variables by hand need to be fixed.

   (KC Sivaramakrishnan and Stephen Dolan,
    compatibility hacking by David Allsopp, Florian Angeletti, Kate Deplaix,
    Jacques Garrigue, Guillaume Munch-Maccagnoni and Nicolás Ojeda Bär,
    review by David Allsopp, Alain Frisch, Nicolás Ojeda Bär,
    Gabriel Scherer, Damien Doligez, and Guillaume Munch-Maccagnoni)

- #8993: New C functions caml_process_pending_actions{,_exn} in
  caml/signals.h, intended for executing all pending actions inside
  long-running C functions (requested minor and major collections,
  signal handlers, finalisers, and memprof callbacks). The function
  caml_process_pending_actions_exn returns any exception arising
  during their execution, allowing resources to be cleaned-up before
  re-raising.
  (Guillaume Munch-Maccagnoni, review by Jacques-Henri Jourdan,
   Stephen Dolan, and Gabriel Scherer)

* #8691, #8897, #9027: Allocation functions are now guaranteed not to
  trigger any OCaml callback when called from C. In long-running C
  functions, this can be replaced with calls to
  caml_process_pending_actions at safe points.
  Side effect of this change: in bytecode mode, polling for
  asynchronous callbacks is performed at every minor heap allocation,
  in addition to function calls and loops as in previous OCaml
  releases.
  (Jacques-Henri Jourdan, review by Stephen Dolan, Gabriel Scherer and
   Guillaume Munch-Maccagnoni)

* #9037: caml_check_urgent_gc is now guaranteed not to trigger any
  finaliser. In long-running C functions, this can be replaced
  with calls to caml_process_pending_actions at safe points.
  (Guillaume Munch-Maccagnoni, review by Jacques-Henri Jourdan and
   Stephen Dolan)


- #8619: Ensure Gc.minor_words remains accurate after a GC.
  (Stephen Dolan, Xavier Leroy and David Allsopp,
   review by Xavier Leroy and Gabriel Scherer)

- #8667: Limit GC credit to 1.0
  (Leo White, review by Damien Doligez)

- #8670: Fix stack overflow detection with systhreads
  (Stephen Dolan, review by Xavier Leroy, Anil Madhavapeddy, Gabriel Scherer,
   Frédéric Bour and Guillaume Munch-Maccagnoni)

* #8711: The major GC hooks are no longer allowed to interact with the
   OCaml heap.
   (Jacques-Henri Jourdan, review by Damien Doligez)

- #8630: Use abort() instead of exit(2) in caml_fatal_error, and add
  the new hook caml_fatal_error_hook.
  (Jacques-Henri Jourdan, review by Xavier Leroy)

- #8641: Better call stacks when a C call is involved in byte code mode
  (Jacques-Henri Jourdan, review by Xavier Leroy)

- #8634, #8668, #8684, #9103 (originally #847): Statistical memory profiling.
  In OCaml 4.10, support for allocations in the minor heap in native
  mode is not available, and callbacks for promotions and
  deallocations are not available.
  Hence, there is not any public API for this feature yet.
  (Jacques-Henri Jourdan, review by Stephen Dolan, Gabriel Scherer
   and Damien Doligez)

- #9268, #9271: Fix bytecode backtrace generation with large integers present.
  (Stephen Dolan and Mark Shinwell, review by Gabriel Scherer and
   Jacques-Henri Jourdan)

### Standard library:

- #8760: List.concat_map : ('a -> 'b list) -> 'a list -> 'b list
  (Gabriel Scherer, review by Daniel Bünzli and Thomas Refis)

- #8832: List.find_map : ('a -> 'b option) -> 'a list -> 'b option
  (Gabriel Scherer, review by Jeremy Yallop, Nicolás Ojeda Bär
   and Daniel Bünzli)

- #7672, #1492: Add `Filename.quote_command` to produce properly-quoted
  commands for execution by Sys.command.
  (Xavier Leroy, review by David Allsopp and Damien Doligez)

- #8971: Add `Filename.null`, the conventional name of the "null" device.
  (Nicolás Ojeda Bär, review by Xavier Leroy and Alain Frisch)

- #8651: add '%#F' modifier in printf to output OCaml float constants
  in hexadecimal
  (Pierre Roux, review by Gabriel Scherer and Xavier Leroy)


- #8657: Optimization in [Array.make] when initializing with unboxed
   or young values.
   (Jacques-Henri Jourdan, review by Gabriel Scherer and Stephen Dolan)

- #8716: Optimize [Array.fill] and [Hashtbl.clear] with a new runtime primitive
  (Alain Frisch, review by David Allsopp, Stephen Dolan and Damien Doligez)

- #8530: List.sort: avoid duplicate work by chop
  (Guillaume Munch-Maccagnoni, review by David Allsopp, Damien Doligez and
   Gabriel Scherer)

### Other libraries:

- #1939, #2023: Implement Unix.truncate and Unix.ftruncate on Windows.
  (Florent Monnier and Nicolás Ojeda Bär, review by David Allsopp)

### Code generation and optimizations:

- #8806: Add an [@@immediate64] attribute for types that are known to
  be immediate only on 64 bit platforms
  (Jérémie Dimino, review by Vladimir Keleshev)

- #9028, #9032: Fix miscompilation by no longer assuming that
  untag_int (tag_int x) = x in Cmmgen; the compilation of `(n lsl 1) + 1`,
  for example, would be incorrect if evaluated with a large value for `n`.
  (Stephen Dolan, review by Vincent Laviron and Xavier Leroy)

- #8672: Optimise Switch code generation on booleans.
  (Stephen Dolan, review by Pierre Chambart)


- #8990: amd64: Emit 32bit registers for Iconst_int when we can
  (Xavier Clerc, Tom Kelly and Mark Shinwell, review by Xavier Leroy)

- #2322: Add pseudo-instruction `Ladjust_trap_depth` to replace
  dummy Lpushtrap generated in linearize
  (Greta Yorsh and Vincent Laviron, review by Xavier Leroy)

- #8707: Simplif: more regular treatment of Tupled and Curried functions
  (Gabriel Scherer, review by Leo White and Alain Frisch)

- #8526: Add compile-time option -function-sections in ocamlopt to emit
  each function in a separate named text section on supported targets.
  (Greta Yorsh, review by Pierre Chambart)

- #2321: Eliminate dead ICatch handlers
  (Greta Yorsh, review by Pierre Chambart and Vincent Laviron)

- #8919: lift mutable lets along with immutable ones
  (Leo White, review by Pierre Chambart)

- #8909: Graph coloring register allocator: the weights put on
  preference edges should not be divided by 2 in branches of
  conditional constructs, because it is not good for performance
  and because it leads to ignoring preference edges with 0 weight.
  (Eric Stavarache, review by Xavier Leroy)

- #9006: int32 code generation improvements
  (Stephen Dolan, designed with Greta Yorsh, review by Xavier Clerc,
   Xavier Leroy and Alain Frisch)

- #9041: amd64: Avoid stall in sqrtsd by clearing destination.
  (Stephen Dolan, with thanks to Andrew Hunter, Will Hasenplaugh,
   Spiros Eliopoulos and Brian Nigito. Review by Xavier Leroy)

- #2165: better unboxing heuristics for let-bound identifiers
  (Alain Frisch, review by Vincent Laviron and Gabriel Scherer)

- #8735: unbox across static handlers
  (Alain Frisch, review by Vincent Laviron and Gabriel Scherer)

### Manual and documentation:

- #8718, #9089: syntactic highlighting for code examples in the manual
  (Florian Angeletti, report by Anton Kochkov, review by Gabriel Scherer)

- #9101: add links to section anchor before the section title,
  make the name of those anchor explicit.
  (Florian Angeletti, review by Daniel Bünzli, Sébastien Hinderer,
   and Gabriel Scherer)

- #9257, cautionary guidelines for using the internal runtime API
  without too much updating pain.
  (Florian Angeletti, review by Daniel Bünzli, Guillaume Munch-Maccagnoni
   and KC Sivaramakrishnan)


- #8950: move local opens in pattern out of the extension chapter
  (Florian Angeletti, review and suggestion by Gabriel Scherer)

- #9088, #9097: fix operator character classes
  (Florian Angeletti, review by Gabriel Scherer,
   report by Clément Busschaert)

- #9169: better documentation for the best-fit allocation policy
  (Gabriel Scherer, review by Guillaume Munch-Maccagnoni
   and Florian Angeletti)

### Compiler user-interface and warnings:

- #8833: Hint for (type) redefinitions in toplevel session
  (Florian Angeletti, review by Gabriel Scherer)

- #2127, #9185: Refactor lookup functions
  Included observable changes:
    - makes the location of usage warnings and alerts for constructors more
      precise
    - don't warn about a constructor never being used to build values when it
      has been defined as private
  (Leo White, Hugo Heuzard review by Thomas Refis, Florian Angeletti)

- #8702, #8777: improved error messages for fixed row polymorphic variants
  (Florian Angeletti, report by Leo White, review by Thomas Refis)

- #8844: Printing faulty constructors, inline records fields and their types
  during type mismatches. Also slightly changed other type mismatches error
  output.
  (Mekhrubon Turaev, review by Florian Angeletti, Leo White)

- #8885: Warn about unused local modules
  (Thomas Refis, review by Alain Frisch)

- #8872: Add ocamlc option "-output-complete-exe" to build a self-contained
  binary for bytecode programs, containing the runtime and C stubs.
  (Stéphane Glondu, Nicolás Ojeda Bär, review by Jérémie Dimino and Daniel
  Bünzli)

- #8874: add tests for typechecking error messages and pack them into
  pretty-printing boxes.
  (Oxana Kostikova, review by Gabriel Scherer)

- #8891: Warn about unused functor parameters
  (Thomas Refis, review by Gabriel Radanne)

- #8903: Improve errors for first-class modules
  (Leo White, review by Jacques Garrigue)

- #8914: clarify the warning on unboxable types used in external primitives (61)
  (Gabriel Scherer, review by Florian Angeletti, report on the Discourse forum)

- #9046: disable warning 30 by default
  This outdated warning complained on label/constructor name conflicts
  within a mutually-recursive type declarations; there is now no need
  to complain thanks to type-based disambiguation.
  (Gabriel Scherer)

### Tools:

* #6792, #8654 ocamldebug now supports programs using Dynlink. This
  changes ocamldebug messages, which may break compatibility
  with older emacs modes.
  (whitequark and Jacques-Henri Jourdan, review by Gabriel Scherer
   and Xavier Clerc)

- #8621: Make ocamlyacc a Windows Unicode application
  (David Allsopp, review by Nicolás Ojeda Bär)

* #8834, `ocaml`: adhere to the XDG base directory specification to
  locate an `.ocamlinit` file. Reads an `$XDG_CONFIG_HOME/ocaml/init.ml`
  file before trying to lookup `~/.ocamlinit`. On Windows the behaviour
  is unchanged.
  (Daniel Bünzli, review by David Allsopp, Armaël Guéneau and
   Nicolás Ojeda Bär)

- #9113: ocamldoc: fix the rendering of multi-line code blocks
  in the 'man' backend.
  (Gabriel Scherer, review by Florian Angeletti)

- #9127, #9130: ocamldoc: fix the formatting of closing brace in record types.
  (David Allsopp, report by San Vũ Ngọc)

- #9181: make objinfo work on Cygwin and look for the caml_plugin_header
  symbol in both the static and the dynamic symbol tables.
  (Sébastien Hinderer, review by Gabriel Scherer and David Allsopp)

### Build system:

- #8840: use ocaml{c,opt}.opt when available to build internal tools
  On my machine this reduces parallel-build times from 3m30s to 2m50s.
  (Gabriel Scherer, review by Xavier Leroy and Sébastien Hinderer)

- #8650: ensure that "make" variables are defined before use;
  revise generation of config/util.ml to better quote special characters
  (Xavier Leroy, review by David Allsopp)

- #8690, #8696: avoid rebuilding the world when files containing primitives
  change.
  (Stephen Dolan, review by Gabriel Scherer, Sébastien Hinderer and
   Thomas Refis)

- #8835: new configure option --disable-stdlib-manpages to disable building
  and installation of the library manpages.
  (David Allsopp, review by Florian Angeletti and Gabriel Scherer)

- #8837: build manpages using ocamldoc.opt when available
  cuts the manpages build time from 14s to 4s
  (Gabriel Scherer, review by David Allsopp and Sébastien Hinderer,
   report by David Allsopp)

- #8843, #8841: fix use of off_t on 32-bit systems.
  (Stephen Dolan, report by Richard Jones, review by Xavier Leroy)

- #8947, #9134, #9302, #9311: fix/improve support for the BFD library
  (Sébastien Hinderer, review by Damien Doligez and David Allsopp)

- #8951: let make's default target build the compiler
  (Sébastien Hinderer, review by David Allsopp)

- #8995: allow developers to specify frequently-used configure options in
  Git (ocaml.configure option) and a directory for host-specific, shareable
  config.cache files (ocaml.configure-cache option). See HACKING.adoc for
  further details.
  (David Allsopp, review by Gabriel Scherer)

- #9136: Don't propagate Cygwin-style prefix from configure to
  Makefile.config on Windows ports.
  (David Allsopp, review by Sébastien Hinderer)

### Internal/compiler-libs changes:

- #8828: Added abstractions for variants, records, constructors, fields and
  extension constructor types mismatch.
  (Mekhrubon Turaev, review by Florian Angeletti, Leo White and Gabriel Scherer)

- #7927, #8527: Replace long tuples into records in typeclass.ml
  (Ulugbek Abdullaev, review by David Allsopp and Gabriel Scherer)

- #1963: split cmmgen into generic Cmm helpers and clambda transformations
  (Vincent Laviron, review by Mark Shinwell)

- #1901: Fix lexing of character literals in comments
  (Pieter Goetschalckx, review by Damien Doligez)

- #1932: Allow octal escape sequences and identifiers containing apostrophes
  in ocamlyacc actions and comments.
  (Pieter Goetschalckx, review by Damien Doligez)

- #2288: Move middle end code from [Asmgen] to [Clambda_middle_end] and
  [Flambda_middle_end].  Run [Un_anf] from the middle end, not [Cmmgen].
  (Mark Shinwell, review by Pierre Chambart)

- #8692: Remove Misc.may_map and similar
  (Leo White, review by Gabriel Scherer and Thomas Refis)

- #8677: Use unsigned comparisons in amd64 and i386 emitter of Lcondbranch3.
  (Greta Yorsh, review by Xavier Leroy)

- #8766: Parmatch: introduce a type for simplified pattern heads
  (Gabriel Scherer and Thomas Refis, review by Stephen Dolan and
   Florian Angeletti)

- #8774: New implementation of Env.make_copy_of_types
  (Alain Frisch, review by Thomas Refis, Leo White and Jacques Garrigue)

- #7924: Use a variant instead of an int in Bad_variance exception
  (Rian Douglas, review by Gabriel Scherer)

- #8890: in -dtimings output, show time spent in C linker clearly
  (Valentin Gatien-Baron)

- #8910, #8911: minor improvements to the printing of module types
  (Gabriel Scherer, review by Florian Angeletti)

- #8913: ocamltest: improve 'promote' implementation to take
  skipped lines/bytes into account
  (Gabriel Scherer, review by Sébastien Hinderer)

- #8908: Use an option instead of a string for module names ("_" becomes None),
  and a dedicated type for functor parameters: "()" maps to "Unit" (instead of
  "*").
  (Thomas Refis, review by Gabriel Radanne)

- #8928: Move contains_calls and num_stack_slots from Proc to Mach.fundecl
  (Greta Yorsh, review by Florian Angeletti and Vincent Laviron)

- #8959, #8960, #8968, #9023: minor refactorings in the typing of patterns:
  + refactor the {let,pat}_bound_idents* functions
  + minor bugfix in type_pat
  + refactor the generic pattern-traversal functions
    in Typecore and Typedtree
  + restrict the use of Need_backtrack
  (Gabriel Scherer and Florian Angeletti,
   review by Thomas Refis and Gabriel Scherer)

- #9030: clarify and document the parameter space of type_pat
  (Gabriel Scherer and Florian Angeletti and Jacques Garrigue,
   review by Florian Angeletti and Thomas Refis)

- #8975: "ocamltests" files are no longer required or used by
  "ocamltest". Instead, any text file in the testsuite directory containing a
  valid "TEST" block will be automatically included in the testsuite.
  (Nicolás Ojeda Bär, review by Gabriel Scherer and Sébastien Hinderer)

- #8992: share argument implementations between executables
  (Florian Angeletti, review by Gabriel Scherer)

- #9015: fix fatal error in pprint_ast (#8789)
  (Damien Doligez, review by Thomas Refis)

### Bug fixes:

- #5673, #7636: unused type variable causes generalization error
  (Jacques Garrigue and Leo White, review by Leo White,
   reports by Jean-Louis Giavitto and Christophe Raffalli)

- #6922, #8955: Fix regression with -principal type inference for inherited
  methods, allowing to compile ocamldoc with -principal
  (Jacques Garrigue, review by Leo White)

- #7925, #8611: fix error highlighting for exceptionally
  long toplevel phrases
  (Kyle Miller, reported by Armaël Guéneau, review by Armaël Guéneau
   and Nicolás Ojeda Bär)

- #8622: Don't generate #! headers over 127 characters.
  (David Allsopp, review by Xavier Leroy and Stephen Dolan)

- #8715: minor bugfixes in CamlinternalFormat; removes the unused
  and misleading function CamlinternalFormat.string_of_formatting_gen
  (Gabriel Scherer and Florian Angeletti,
   review by Florian Angeletti and Gabriel Radanne)

- #8792, #9018: Possible (latent) bug in Ctype.normalize_type
  removed incrimined Btype.log_type, replaced by Btype.set_type
  (Jacques Garrigue, report by Alain Frisch, review by Thomas Refis)

- #8856, #8860: avoid stackoverflow when printing cyclic type expressions
  in some error submessages.
  (Florian Angeletti, report by Mekhrubon Turaev, review by Leo White)

- #8875: fix missing newlines in the output from MSVC invocation.
  (Nicolás Ojeda Bär, review by Gabriel Scherer)

- #8921, #8924: Fix stack overflow with Flambda
  (Vincent Laviron, review by Pierre Chambart and Leo White,
   report by Aleksandr Kuzmenko)

- #8892, #8895: fix the definition of Is_young when CAML_INTERNALS is not
  defined.
  (David Allsopp, review by Xavier Leroy)

- #8896: deprecate addr typedef in misc.h
  (David Allsopp, suggestion by Xavier Leroy)

- #8981: Fix check for incompatible -c and -o options.
  (Greta Yorsh, review by Damien Doligez)

- #9019, #9154: Unsound exhaustivity of GADTs from incomplete unification
  Also fixes bug found by Thomas Refis in #9012
  (Jacques Garrigue, report and review by Leo White, Thomas Refis)

- #9031: Unregister Windows stack overflow handler while shutting
  the runtime down.
  (Dmitry Bely, review by David Allsopp)

- #9051: fix unregistered local root in win32unix/select.c (could result in
  `select` returning file_descr-like values which weren't in the original sets)
  and correct initialisation of some blocks allocated with caml_alloc_small.
  (David Allsopp, review by Xavier Leroy)

- #9073, #9120: fix incorrect GC ratio multiplier when allocating custom blocks
  with caml_alloc_custom_mem in runtime/custom.c
  (Markus Mottl, review by Gabriel Scherer and Damien Doligez)

- #9209, #9212: fix a development-version regression caused by #2288
  (Kate Deplaix and David Allsopp, review by Sébastien Hinderer
   and Gabriel Scherer )

- #9218, #9269: avoid a rare wrong module name error with "-annot" and
  inline records.
  (Florian Angeletti, review by Gabriel Scherer, report by Kate Deplaix)

- #9261: Fix a soundness bug in Rec_check, new in 4.10 (from #8908)
  (Vincent Laviron, review by Jeremy Yallop and Gabriel Scherer)

OCaml 4.09 maintenance branch
-----------------------------

### Build system:

- #9383: Don't assume that AWKPATH includes .
  (David Allsopp, report by Ian Zimmerman)

OCaml 4.09.1 (16 Mars 2020)
---------------------------

- #8855, #8858: Links for tools not created when installing with
  --disable-installing-byecode-programs (e.g. ocamldep.opt installed, but
  ocamldep link not created)
  (David Allsopp, report by Thomas Leonard)

- #8953, #8954: Fix error submessages in the toplevel: do not display
  dummy locations
  (Armaël Guéneau, review by Gabriel Scherer)

- #8965, #8979: Alpine build failure caused by check-parser-uptodate-or-warn.sh
  (Gabriel Scherer and David Allsopp, report by Anton Kochkov)

- #8985, #8986: fix generation of the primitives when the locale collation is
  incompatible with C.
  (David Allsopp, review by Nicolás Ojeda Bär, report by Sebastian Rasmussen)

- #9050, #9076: install missing compilerlibs/ocamlmiddleend archives
  (Gabriel Scherer, review by Florian Angeletti, report by Olaf Hering)

- #9180: pass -fno-common option to C compiler when available,
  so as to detect problematic multiple definitions of global variables
  in the C runtime
  (Xavier Leroy, review by Mark Shinwell)

- #9144, #9180: multiple definitions of global variables in the C runtime,
  causing problems with GCC 10.0 and possibly with other C compilers
  (Xavier Leroy, report by Jürgen Reuter, review by Mark Shinwell)

- #9128: Fix a bug in bytecode mode which could lead to a segmentation
  fault. The bug was caused by the fact that the atom table shared a
  page with some bytecode. The fix makes sure both the atom table and
  the minor heap have their own pages.
  (Jacques-Henri Jourdan, review by Stephen Dolan, Xavier Leroy and
   Gabriel Scherer)

OCaml 4.09.0 (19 September 2019)
--------------------------------

### Runtime system:

* #1725, #2279: Deprecate Obj.set_tag and Obj.truncate
  (Stephen Dolan, review by Gabriel Scherer, Damien Doligez and Xavier Leroy)

* #2240: Constify "identifier" in struct custom_operations
  (Cedric Cellier, review by Xavier Leroy)

* #2293: Constify "caml_named_value"
  (Stephen Dolan, review by Xavier Leroy)

- #8787, #8788: avoid integer overflow in caml_output_value_to_bytes
  (Jeremy Yallop, report by Marcello Seri)


- #2075, #7729: rename _T macro used to support Unicode in the (Windows) runtime
  in order to avoid compiler warning
  (Nicolás Ojeda Bär, review by Gabriel Scherer and David Allsopp)

- #2250: Remove extra integer sign-extension in compare functions
  (Stefan Muenzel, review by Xavier Leroy)

- #8607: Remove obsolete macros for pre-2002 MSVC support
  (Stephen Dolan, review by Nicolás Ojeda Bär and David Allsopp)

- #8656: Fix a bug in [caml_modify_generational_global_root]
  (Jacques-Henri Jourdan, review by Gabriel Scherer)

### Standard library:

- #2262: take precision (.<n>) and flags ('+' and ' ') into account
  in printf %F
  (Pierre Roux, review by Gabriel Scherer)

- #6148, #8596: optimize some buffer operations
  (Damien Doligez, reports by John Whitington and Alain Frisch,
   review by Jeremy Yallop and Gabriel Scherer)

### Other libraries:

* #2318: Delete the graphics library. This library is now available
  as a separate "graphics" package in opam. Its new home is:
  https://github.com/ocaml/graphics
  (Jérémie Dimino, review by Nicolás Ojeda Bär, Xavier Leroy and
   Sébastien Hinderer)

* #2289: Delete the vmthreads library. This library was deprecated in 4.08.0.
  (Jérémie Dimino)

- #2112: Fix Thread.yield unfairness with busy threads yielding to each
  other.
  (Andrew Hunter, review by Jacques-Henri Jourdan, Spiros Eliopoulos, Stephen
  Weeks, Mark Shinwell)

- #7903, #2306: Make Thread.delay interruptible by signals again
  (Xavier Leroy, review by Jacques-Henri Jourdan and Edwin Török)

- #2248: Unix alloc_sockaddr: Fix read of uninitialized memory for an
  unbound Unix socket. Add support for receiving abstract (Linux) socket paths.
  (Tim Cuthbertson, review by Sébastien Hinderer and Jérémie Dimino)

### Compiler user-interface and warnings:

* #2276: Remove support for compiler plugins and hooks (also adds
  [Dynlink.unsafe_get_global_value])
  (Mark Shinwell, Xavier Clerc, review by Nicolás Ojeda Bär,
  Florian Angeletti, David Allsopp and Xavier Leroy)

- #2301: Hint on type error on int literal
  (Jules Aguillon, review by Nicolás Ojeda Bär , Florian Angeletti,
  Gabriel Scherer and Armaël Guéneau)

* #2314: Remove support for gprof profiling.
  (Mark Shinwell, review by Xavier Clerc and Stephen Dolan)

- #2190: fix pretty printing (using Pprintast) of "lazy ..." patterns and
  "fun (type t) -> ..." expressions.
  (Nicolás Ojeda Bär, review by Gabriel Scherer)

- #2277: Use newtype names as type variable names
  The inferred type of (fun (type t) (x : t) -> x)
  is now printed as ('t -> 't) rather than ('a -> 'a).
  (Matthew Ryan)


- #2309: New options -with-runtime and -without-runtime in ocamlopt/ocamlc
  that control the inclusion of the runtime system in the generated program.
  (Lucas Pluvinage, review by Daniel Bünzli, Damien Doligez, David Allsopp
   and Florian Angeletti)

- #3819, #8546 more explanations and tests for illegal permutation
  (Florian Angeletti, review by Gabriel Scherer)

- #8537: fix the -runtime-variant option for bytecode
  (Damien Doligez, review by David Allsopp)

- #8541: Correctly print multi-lines locations
  (Louis Roché, review by Gabriel Scherer)

- #8579: Better error message for private constructors
  of an extensible variant type
  (Guillaume Bury, review by many fine eyes)

### Code generation and optimizations:

- #2278: Remove native code generation support for 32-bit Intel macOS,
  iOS and other Darwin targets.
  (Mark Shinwell, review by Nicolás Ojeda Bär and Xavier Leroy)

- #8547: Optimize matches that are an affine function of the input.
  (Stefan Muenzel, review by Alain Frisch, Gabriel Scherer)


- #1904, #7931: Add FreeBSD/aarch64 support
  (Greg V, review by Sébastien Hinderer, Stephen Dolan, Damien Doligez
   and Xavier Leroy)

- #8507: Shorten symbol names of anonymous functions in Flambda mode
  (the directory portions are now hidden)
  (Mark Shinwell, review by Nicolás Ojeda Bär)

- #8681, #8699, #8712: Fix code generation with nested let rec of functions.
  (Stephen Dolan, Leo White, Gabriel Scherer and Pierre Chambart,
   review by Gabriel Scherer, reports by Alexey Solovyev and Jonathan French)

### Manual and documentation:

- #7584, #8538: Document .cmt* files in the "overview" of ocaml{c,opt}
  (Oxana Kostikova, rewiew by Florian Angeletti)


- #8757: Rename Pervasives to Stdlib in core library documentation.
  (Ian Zimmerman, review by David Allsopp)

- #8515: manual, precise constraints on reexported types
  (Florian Angeletti, review by Gabriel Scherer)

### Tools:

- #2221: ocamldep will now correctly allow a .ml file in an include directory
  that appears first in the search order to shadow a .mli appearing in a later
  include directory.
  (Nicolás Ojeda Bär, review by Florian Angeletti)

### Internal/compiler-libs changes:

- #1579: Add a separate types for clambda primitives
  (Pierre Chambart, review by Vincent Laviron and Mark Shinwell)

- #1965: remove loop constructors in Cmm and Mach
  (Vincent Laviron)

- #1973: fix compilation of catches with multiple handlers
  (Vincent Laviron)

- #2228, #8545: refactoring the handling of .cmi files
  by moving the logic from Env to a new module Persistent_env
  (Gabriel Scherer, review by Jérémie Dimino and Thomas Refis)

- #2229: Env: remove prefix_idents cache
  (Thomas Refis, review by Frédéric Bour and Gabriel Scherer)

- #2237, #8582: Reorder linearisation of Trywith to avoid a call instruction
  (Vincent Laviron and Greta Yorsh, additional review by Mark Shinwell;
  fix in #8582 by Mark Shinwell, Xavier Leroy and Anil Madhavapeddy)

- #2265: Add bytecomp/opcodes.mli
  (Mark Shinwell, review by Nicolás Ojeda Bär)

- #2268: Improve packing mechanism used for building compilerlibs modules
  into the Dynlink libraries
  (Mark Shinwell, Stephen Dolan, review by David Allsopp)

- #2280: Don't make more Clambda constants after starting Cmmgen
  (Mark Shinwell, review by Vincent Laviron)

- #2281: Move some middle-end files around
  (Mark Shinwell, review by Pierre Chambart and Vincent Laviron)

- #2283: Add [is_prefix] and [find_and_chop_longest_common_prefix] to
  [Misc.Stdlib.List]
  (Mark Shinwell, review by Alain Frisch and Stephen Dolan)

- #2284: Add various utility functions to [Misc] and remove functions
  from [Misc.Stdlib.Option] that are now in [Stdlib.Option]
  (Mark Shinwell, review by Thomas Refis)

- #2286: Functorise [Consistbl]
  (Mark Shinwell, review by Gabriel Radanne)

- #2291: Add [Compute_ranges] pass
  (Mark Shinwell, review by Vincent Laviron)

- #2292: Add [Proc.frame_required] and [Proc.prologue_required].
  Move tail recursion label creation to [Linearize].  Correctly position
  [Lprologue] relative to [Iname_for_debugger] operations.
  (Mark Shinwell, review by Vincent Laviron)

- #2308: More debugging information on [Cmm] terms
  (Mark Shinwell, review by Stephen Dolan)

- #7878, #8542: Replaced TypedtreeIter with tast_iterator
  (Isaac "Izzy" Avram, review by Gabriel Scherer and Nicolás Ojeda Bär)

- #8598: Replace "not is_nonexpansive" by "maybe_expansive".
  (Thomas Refis, review by David Allsopp, Florian Angeletti, Gabriel Radanne,
   Gabriel Scherer and Xavier Leroy)

### Compiler distribution build system:

- #2267: merge generation of header programs, also fixing parallel build on
  Cygwin.
  (David Allsopp, review by Sébastien Hinderer)

- #8514: Use boot/ocamlc.opt for building, if available.
  (Stephen Dolan, review by Gabriel Scherer)

### Bug fixes:

- #8864, #8865: Fix native compilation of left shift by (word_size - 1)
  (Vincent Laviron, report by Murilo Giacometti Rocha, review by Xavier Leroy)

- #2296: Fix parsing of hexadecimal floats with underscores in the exponent.
  (Hugo Heuzard and Xavier Leroy, review by Gabriel Scherer)

- #8800: Fix soundness bug in extension constructor inclusion
  (Leo White, review by Jacques Garrigue)

- #8848: Fix x86 stack probe CFI information in caml_c_call and
  caml_call_gc
  (Tom Kelly, review by Xavier Leroy)


- #7156, #8594: make top level use custom printers if they are available
  (Andrew Litteken, report by Martin Jambon, review by Nicolás Ojeda Bär,
   Thomas Refis, Armaël Guéneau, Gabriel Scherer, David Allsopp)

- #3249: ocamlmklib should reject .cmxa files
  (Xavier Leroy)

- #7937, #2287: fix uncaught Unify exception when looking for type
  declaration
  (Florian Angeletti, review by Jacques Garrigue)

- #8610, #8613: toplevel printing, consistent deduplicated name for types
  (Florian Angeletti, review by Thomas Refis and Gabriel Scherer,
   reported by Xavier Clerc)

- #8635, #8636: Fix a bad side-effect of the -allow-approx option of
  ocamldep. It used to turn some errors into successes
  (Jérémie Dimino)

- #8701, #8725: Variance of constrained parameters causes principality issues
  (Jacques Garrigue, report by Leo White, review by Gabriel Scherer)

- #8777(partial): fix position information in some polymorphic variant
  error messages about missing tags
  (Florian Angeletti, review by Thomas Refis)

- #8779, more cautious variance computation to avoid missing cmis
  (Florian Angeletti, report by Antonio Nuno Monteiro, review by Leo White)

- #8810: Env.lookup_module: don't allow creating loops
  (Thomas Refis, report by Leo White, review by Jacques Garrigue)

- #8862, #8871: subst: preserve scopes
  (Thomas Refis, report by Leo White, review by Jacques Garrigue)

- #8921, #8924: Fix stack overflow with Flambda
  (Vincent Laviron, review by Pierre Chambart and Leo White,
   report by Aleksandr Kuzmenko)

- #8944: Fix "open struct .. end" on clambda backend
  (Thomas Refis, review by Leo White, report by Damon Wang and Mark Shinwell)

OCaml 4.08 maintenance branch
-----------------------------

### Bug fixes:

- #9326, #10125: Gc.set incorrectly handles the three `custom_*` fields,
  causing a performance regression
  (report by Emilio Jesús Gallego Arias, analysis and fix by Stephen Dolan,
   code by Xavier Leroy, review by Hugo Heuzard and Gabriel Scherer)

OCaml 4.08.1 (5 August 2019)
----------------------------

### Bug fixes:

- #7887: ensure frame table is 8-aligned on ARM64 and PPC64
  (Xavier Leroy, report by Mark Hayden, review by Mark Shinwell
   and Gabriel Scherer)

- #8751: fix bug that could result in misaligned data section when compiling to
  native-code on amd64.  (observed with the mingw64 compiler)
  (Nicolás Ojeda Bär, review by David Allsopp)

- #8769, #8770: Fix assertion failure with -pack
  (Leo White, review by Gabriel Scherer, report by Fabian @copy)

- #8816, #8818: fix loading of packed modules with Dynlink (regression in
  #2176).
  (Leo White, report by Andre Maroneze, review by Gabriel Scherer)

- #8830: configure script: fix tool prefix detection and Debian's armhf
  detection
  (Stéphane Glondu, review by David Allsopp)

- #8843, #8841: fix use of off_t on 32-bit systems.
  (Stephen Dolan, report by Richard Jones, review by Xavier Leroy)

OCaml 4.08.0 (13 June 2019)
---------------------------

### Language features:

- #1947: Introduce binding operators (let*, let+, and* etc.)
  (Leo White, review by Thomas Refis)

- #1892: Allow shadowing of items coming from an include
  (Thomas Refis, review by Gabriel Radanne)

- #2122: Introduce local substitutions in signatures: "type t := type_expr"
  and "module M := Extended(Module).Path"
  (Thomas Refis, with help and review from Leo White, and Alain Frisch)

- #1804: New notion of "alerts" that generalizes the deprecated warning
      [@@ocaml.alert deprecated "Please use bar instead!"]
      [@@ocaml.alert unsafe "Please use safe_foo instead!"]
  (Alain Frisch, review by Leo White and Damien Doligez)

- #6422, #7083, #305, #1568: Allow `exception` under or-patterns
  (Thomas Refis, with help and review from Alain Frisch, Gabriel Scherer, Jeremy
  Yallop, Leo White and Luc Maranget)


- #1705: Allow @@attributes on exception declarations.
  (Hugo Heuzard, review by Gabriel Radanne and Thomas Refis)

- #1506, #2147, #2166, #2167: Extended `open` to arbitrary module
  expression in structures and to applicative paths in signatures
  (Runhang Li, review by Alain Frisch, Florian Angeletti, Jeremy Yallop,
  Leo White and Thomas Refis)

* #2106: .~ is now a reserved keyword, and is no longer available
  for use in extended indexing operators
  (Jeremy Yallop, review by Gabriel Scherer, Florian Angeletti, and
   Damien Doligez)

* #7841, #2041, #2235: allow modules from include directories
  to shadow other ones, even in the toplevel; for a example, including
  a directory that defines its own Result module will shadow the stdlib's.
  (Jérémie Dimino, review by Alain Frisch and David Allsopp)

### Type system:

- #2110: Partial support for GADTs inside or-patterns;
  The type equalities introduced by the GADT constructor are only
  available inside the or-pattern; they cannot be used in the
  right-hand-side of the clause, when both sides of the or-pattern
  agree on it.
  (Thomas Refis and Leo White, review by Jacques Garrigue)

- #1826: allow expanding a type to a private abbreviation instead of
  abstracting when removing references to an identifier.
  (Thomas Refis and Leo White, review by Jacques Garrigue)

- #1942, #2244: simplification of the static check
  for recursive definitions
  (Alban Reynaud and Gabriel Scherer,
   review by Jeremy Yallop, Armaël Guéneau and Damien Doligez)

### Standard library:

- #2128: Add Fun module: `id, const, flip, negate, protect`
  (protect is a "try_finally" combinator)
  https://caml.inria.fr/pub/docs/manual-ocaml/libref/Fun.html
  (Many fine eyes)

- #2010: Add Bool module
  https://caml.inria.fr/pub/docs/manual-ocaml/libref/Bool.html
  (Many fine eyes)

- #2011: Add Int module
  https://caml.inria.fr/pub/docs/manual-ocaml/libref/Int.html
  (Many fine eyes)

- #1940: Add Option module and Format.pp_print_option
  `none, some, value, get, bind, join, map, fold, iter`, etc.
  https://caml.inria.fr/pub/docs/manual-ocaml/libref/Option.html
  (Many fine eyes)

- #1956: Add Result module and Format.pp_print_result
  `ok, error, value, get_ok, bind, join, map, map_error`, etc.
  https://caml.inria.fr/pub/docs/manual-ocaml/libref/Result.html
  (Many fine eyes)

- #1855, #2118: Add `Fun.protect ~finally` for enforcing local
  invariants whether a function raises or not, similar to
  `unwind-protect` in Lisp and `FINALLY` in Modula-2. It is careful
  about preserving backtraces and treating exceptions in finally as
  errors.
  (Marcello Seri and Guillaume Munch-Maccagnoni, review by Daniel
  Bünzli, Gabriel Scherer, François Bobot, Nicolás Ojeda Bär, Xavier
  Clerc, Boris Yakobowski, Damien Doligez, and Xavier Leroy)

* #1605: Deprecate Stdlib.Pervasives. Following #1010, Pervasives
  is no longer needed and Stdlib should be used instead.
  (Jérémie Dimino, review by Nicolás Ojeda Bär)

- #2185: Add `List.filter_map`
  (Thomas Refis, review by Alain Frisch and Gabriel Scherer)

- #1957: Add Stack.{top_opt,pop_opt} and Queue.{peek_opt,take_opt}.
  (Vladimir Keleshev, review by Nicolás Ojeda Bär and Gabriel Scherer)

- #1182: Add new Printf formats %#d %#Ld %#ld %#nd (idem for %i and %u) for
  alternative integer formatting -- inserts '_' between blocks of digits.
  (ygrek, review by Gabriel Scherer)

- #1959: Add Format.dprintf, a printing function which outputs a closure
  usable with %t.
  (Gabriel Radanne, request by Armaël Guéneau,
   review by Florian Angeletti and Gabriel Scherer)

- #1986, #6450: Add Set.disjoint
  (Nicolás Ojeda Bär, review by Gabriel Scherer)

- #7812, #2125: Add Filename.chop_suffix_opt
  (Alain Frisch, review by Nicolás Ojeda Bär, suggestion by whitequark)

- #1864: Extend Bytes and Buffer with functions to read/write
  binary representations of numbers
  (Alain Frisch and Daniel Bünzli)

- #1458: Add unsigned operations unsigned_div, unsigned_rem, unsigned_compare
  and unsigned_to_int to modules Int32, Int64, Nativeint.
  (Nicolás Ojeda Bär, review by Daniel Bünzli, Alain Frisch and Max Mouratov)

- #2002: Add Format.pp_print_custom_break, a new more general kind of break
  hint that can emit non-whitespace characters.
  (Vladimir Keleshev and Pierre Weis, review by Josh Berdine, Gabriel Radanne)

- #1966: Add Format semantic tags using extensible sum types.
  (Gabriel Radanne, review by Nicolás Ojeda Bär)

- #1794: Add constants zero, one, minus_one and functions succ,
  pred, is_finite, is_infinite, is_nan, is_integer, trunc, round,
  next_after, sign_bit, min, max, min_max, min_num, max_num,
  min_max_num to module Float.
  (Christophe Troestler, review by Alain Frisch, Xavier Clerc and Daniel Bünzli)

- #1354, #2177: Add fma support to Float module.
  (Laurent Thévenoux, review by Alain Frisch, Jacques-Henri Jourdan,
  Xavier Leroy)



- #5072, #6655, #1876: add aliases in Stdlib for built-in types
  and exceptions.
  (Jeremy Yallop, reports by Pierre Letouzey and David Sheets,
   review by Valentin Gatien-Baron, Gabriel Scherer and Alain Frisch)

- #1731: Format, use raise_notrace to preserve backtraces.
  (Frédéric Bour, report by Jules Villard, review by Gabriel Scherer)

- #6701, #1185, #1803: make float_of_string and string_of_float
  locale-independent.
  (ygrek, review by Xavier Leroy and Damien Doligez)

- #7795, #1782: Fix off-by-one error in Weak.create.
  (KC Sivaramakrishnan, review by Gabriel Scherer and François Bobot)

- #7235: Format, flush err_formatter at exit.
  (Pierre Weis, request by Jun Furuse)

- #1857, #7812: Remove Sort module, deprecated since 2000 and emitting
  a deprecation warning since 4.02.
  (whitequark)

- #1923: Arg module sometimes misbehaved instead of rejecting invalid
  -keyword=arg inputs
  (Valentin Gatien-Baron, review by Gabriel Scherer)

- #1959: Small simplification and optimization to Format.ifprintf
  (Gabriel Radanne, review by Gabriel Scherer)

- #2119: clarify the documentation of Set.diff
  (Gabriel Scherer, suggestion by John Skaller)

- #2145: Deprecate the mutability of Gc.control record fields
  (Damien Doligez, review by Alain Frisch)

- #2159, #7874: annotate {String,Bytes}.equal as being [@@noalloc].
  (Pierre-Marie Pédrot, review by Nicolás Ojeda Bär)

- #1936: Add module Float.Array
  (Damien Doligez, review by Xavier Clerc and Alain Frisch)

- #2183: Fix segfault in Array.create_float with -no-flat-float-array
  (Damien Doligez, review by Gabriel Scherer and Jeremy Yallop)

- #1525: Make function set_max_indent respect documentation
  (Pierre Weis, Richard Bonichon, review by Florian Angeletti)

- #2202: Correct Hashtbl.MakeSeeded.{add_seq,replace_seq,of_seq} to use
  functor hash function instead of default hash function. Hashtbl.Make.of_seq
  shouldn't create randomized hash tables.
  (David Allsopp, review by Alain Frisch)

### Other libraries:

- #2533, #1839, #1949: added Unix.fsync
  (François Berenger, Nicolás Ojeda Bär, review by Daniel Bünzli, David Allsopp
  and ygrek)

- #1792, #7794: Add Unix.open_process_args{,_in,_out,_full} similar to
  Unix.open_process{,_in,_out,_full}, but passing an explicit argv array.
  (Nicolás Ojeda Bär, review by Jérémie Dimino, request by Volker Diels-Grabsch)

- #1999: Add Unix.process{,_in,_out,_full}_pid to retrieve opened process's
  pid.
  (Romain Beauxis, review by Nicolás Ojeda Bär)

- #2222: Set default status in waitpid when pid is zero. Otherwise,
  status value is undefined.
  (Romain Beauxis and Xavier Leroy, review by Stephen Dolan)

* #2104, #2211, #4127, #7709: Fix Thread.sigmask. When
  system threads are loaded, Unix.sigprocmask is now an alias for
  Thread.sigmask. This changes the behavior at least on MacOS, where
  Unix.sigprocmask used to change the masks of all threads.
  (Jacques-Henri Jourdan, review by Jérémie Dimino)

- #1061: Add ?follow parameter to Unix.link. This allows hardlinking
  symlinks.
  (Christopher Zimmermann, review by Xavier Leroy, Damien Doligez, David
   Allsopp, David Sheets)

- #2038: Deprecate vm threads.
  OCaml supported both "native threads", based on pthreads,
  and its own green-threads implementation, "vm threads". We are not
  aware of any recent usage of "vm threads", and removing them simplifies
  further maintenance.
  (Jérémie Dimino)

* #4208, #4229, #4839, #6462, #6957, #6950, #1063, #2176,
  #2297: Make (nat)dynlink sound by correctly failing when
  dynlinked module names clash with other modules or interfaces.
  (Mark Shinwell, Leo White, Nicolás Ojeda Bär, Pierre Chambart)

- #2263: Delete the deprecated Bigarray.*.map_file functions in
  favour of `*_of_genarray (Unix.map_file ...)` functions instead. The
  `Unix.map_file` function was introduced in OCaml 4.06.0 onwards.
  (Jérémie Dimino, reviewed by David Allsopp and Anil Madhavapeddy)

### Compiler user-interface and warnings:

- #2096: Add source highlighting for errors & warnings in batch mode
  (Armaël Guéneau, review by Gabriel Scherer and Jérémie Dimino)

- #2133: [@ocaml.warn_on_literal_pattern]: now warn on literal patterns
  found anywhere in a constructor's arguments.
  (Jeremy Yallop, review by Gabriel Scherer)

- #1720: Improve error reporting for missing 'rec' in let-bindings.
  (Arthur Charguéraud and Armaël Guéneau, with help and advice
   from Gabriel Scherer, Frédéric Bour, Xavier Clerc and Leo White)

- #7116, #1430: new -config-var option
  to get the value of a single configuration variable in scripts.
  (Gabriel Scherer, review by Sébastien Hinderer and David Allsopp,
   request by Adrien Nader)

- #1733,1993,1998,2058,2094,2140: Typing error message improvements
    - #1733, change the perspective of the unexpected existential error
      message.
    - #1993, expanded error messages for universal quantification failure
    - #1998, more context for unbound type parameter error
    - #2058, full explanation for unsafe cycles in recursive module
      definitions (suggestion by Ivan Gotovchits)
    - #2094, rewording for "constructor has no type" error
    - #7565, #2140, more context for universal variable escape
      in method type
  (Florian Angeletti, reviews by Jacques Garrigue, Armaël Guéneau,
   Gabriel Radanne, Gabriel Scherer and Jeremy Yallop)

- #1913: new flag -dump-into-file to print debug output like -dlambda into
  a file named after the file being built, instead of on stderr.
  (Valentin Gatien-Baron, review by Thomas Refis)

- #1921: in the compilation context passed to ppx extensions,
  add more configuration options related to type-checking:
  -rectypes, -principal, -alias-deps, -unboxed-types, -unsafe-string
  (Gabriel Scherer, review by Gabriel Radanne, Xavier Clerc and Frédéric Bour)

- #1976: Better error messages for extension constructor type mismatches
  (Thomas Refis, review by Gabriel Scherer)

- #1841, #7808: the environment variable OCAMLTOP_INCLUDE_PATH can now
  specify a list of additional include directories for the ocaml toplevel.
  (Nicolás Ojeda Bär, request by Daniel Bünzli, review by Daniel Bünzli and
  Damien Doligez)

- #6638, #1110: introduced a dedicated warning to report
  unused "open!" statements
  (Alain Frisch, report by dwang, review by and design from Leo White)

- #1974: Trigger warning 5 in "let _ = e" and "ignore e" if e is of function
  type and syntactically an application. (For the case of "ignore e" the warning
  already existed, but used to be triggered even when e was not an application.)
  (Nicolás Ojeda Bär, review by Alain Frisch and Jacques Garrigue)

- #7408, #7846, #2015: Check arity of primitives.
  (Hugo Heuzard, review by Nicolás Ojeda Bär)



- #2091: Add a warning triggered by type declarations "type t = ()"
  (Armaël Guéneau, report by linse, review by Florian Angeletti and Gabriel
  Scherer)

- #2004: Use common standard library path `lib/ocaml` for Windows,
  for consistency with OSX & Linux. Previously was located at `lib`.
  (Bryan Phelps, Jordan Walke, review by David Allsopp)

- #6416, #1120: unique printed names for identifiers
  (Florian Angeletti, review by Jacques Garrigue)

- #1691: add shared_libraries to ocamlc -config exporting
  SUPPORTS_SHARED_LIBRARIES from Makefile.config.
  (David Allsopp, review by Gabriel Scherer and Mark Shinwell)

- #6913, #1786: new -match-context-rows option
  to control the degree of optimization in the pattern matching compiler.
  (Dwight Guth, review by Gabriel Scherer and Luc Maranget)

- #1822: keep attributes attached to pattern variables from being discarded.
  (Nicolás Ojeda Bär, review by Thomas Refis)

- #1845: new `-dcamlprimc` option to keep the generated C file containing
  the information about primitives; pass `-fdebug-prefix-map` to the C compiler
  when supported, for reproducible builds
  (Xavier Clerc, review by Jérémie Dimino)

- #1856, #1869: use `BUILD_PATH_PREFIX_MAP` when compiling primitives
  in order to make builds reproducible if code contains uses of
  `__FILE__` or `__LOC__`
  (Xavier Clerc, review by Gabriel Scherer and Sébastien Hinderer)

- #1906: the -unsafe option does not apply to marshalled ASTs passed
  to the compiler directly or by a -pp preprocessor; add a proper
  warning (64) instead of a simple stderr message
  (Valentin Gatien-Baron)

- #1925: Print error locations more consistently between batch mode, toplevel
  and expect tests
  (Armaël Guéneau, review by Thomas Refis, Gabriel Scherer and François Bobot)

- #1930: pass the elements from `BUILD_PATH_PREFIX_MAP` to the assembler
  (Xavier Clerc, review by Gabriel Scherer, Sébastien Hinderer, and
   Xavier Leroy)

- #1945, #2032: new "-stop-after [parsing|typing]" option
  to stop compilation after the parsing or typing pass
  (Gabriel Scherer, review by Jérémie Dimino)

- #1953: Add locations to attributes in the parsetree.
  (Hugo Heuzard, review by Gabriel Radanne)

- #1954: Add locations to toplevel directives.
  (Hugo Heuzard, review by Gabriel Radanne)

* #1979: Remove support for TERM=norepeat when displaying errors
  (Armaël Guéneau, review by Gabriel Scherer and Florian Angeletti)

- #1960: The parser keeps previous location when relocating ast node.
  (Hugo Heuzard, review by Jérémie Dimino)

- #7864, #2109: remove duplicates from spelling suggestions.
  (Nicolás Ojeda Bär, review by Armaël Guéneau)

### Manual and documentation:

- #7548: printf example in the tutorial part of the manual
 (Kostikova Oxana, rewiew by Gabriel Scherer, Florian Angeletti,
 Marcello Seri and Armaël Guéneau)

- #7546, #2020: preambles and introduction for compiler-libs.
  (Florian Angeletti, review by Daniel Bünzli, Perry E. Metzger
  and Gabriel Scherer)

- #7547, #2273: Tutorial on Lazy expressions and patterns in OCaml Manual
  (Ulugbek Abdullaev, review by Florian Angeletti and Gabriel Scherer)

- #7720, #1596, precise the documentation
  of the maximum indentation limit in Format.
  (Florian Angeletti, review by Richard Bonichon and Pierre Weis)

- #7825: html manual split compilerlibs from stdlib in the html
  index of modules
  (Florian Angeletti, review by Perry E. Metzger and Gabriel Scherer)

- #1209, #2008: in the Extension section, use the caml_example environment
  (uses the compiler to check the example code).
  This change was made possible by a lot of tooling work from Florian Angeletti:
  #1702, #1765, #1863, and Gabriel Scherer's #1903.
  (Gabriel Scherer, review by Florian Angeletti)

- #1788, 1831, 2007, 2198, 2232, move language extensions to the core
  chapters:
     - #1788: quoted string description
     - #1831: local exceptions and exception cases
     - #2007: 32-bit, 64-bit and native integer literals
     - #2198: lazy patterns
     - #2232: short object copy notation
  (Florian Angeletti, review by Xavier Clerc, Perry E. Metzger, Gabriel Scherer
   and Jeremy Yallop)

- #1863: caml-tex2, move to compiler-libs
  (Florian Angeletti, review by Sébastien Hinderer and Gabriel Scherer)

- #2105: Change verbatim to caml_example in documentation
  (Maxime Flin, review by Florian Angeletti)

- #2114: ocamldoc, improved manpages for documentation inside modules
  (Florian Angeletti, review by Gabriel Scherer)

- #2117: stdlib documentation, duplicate the operator precedence table
  from the manual inside a separate "OCaml_operators" module.
  (Florian Angeletti, review by Daniel Bünzli, Perry E. Metzger
  and Gabriel Scherer)

- #2187: document "exception A | pat" patterns
  (Florian Angeletti, review by Perry E. Metzger and Jeremy Yallop)

- #8508: refresh \moduleref macro
  (Florian Angeletti, review by Gabriel Scherer)

### Code generation and optimizations:

- #7725, #1754: improve AFL instrumentation for objects and lazy values.
  (Stephen Dolan)

- #1631: AMD64 code generator: emit shorter instruction sequences for the
  sign-extension operations.
  (LemonBoy, review by Alain Frisch and Xavier Leroy)

- #7246, #2146: make a few int64 primitives use [@@unboxed]
  stubs on 32bits
  (Jérémie Dimino)

- #1917: comballoc: ensure object allocation order is preserved
  (Stephen Dolan)

- #6242, #2143, #8558, #8559: Optimize some local functions.
  Local functions that do not escape and whose calls all have
  the same continuation are lowered into a static-catch handler.
  (Alain Frisch, review by Gabriel Scherer)

- #2082: New options [-insn-sched] and [-no-insn-sched] to control
  instruction scheduling.
  (Mark Shinwell, review by Damien Doligez)

- #2239: Fix match miscompilation with flambda
  (Leo White, review by Alain Frisch)

### Runtime system:

- #7198, #7750, #1738: add a function (caml_alloc_custom_mem)
  and three GC parameters to give the user better control of the
  out-of-heap memory retained by custom values; use the function to
  allocate bigarrays and I/O channels.
  (Damien Doligez, review by Alain Frisch)

- #1793: add the -m and -M command-line options to ocamlrun.
  Option -m prints the magic number of the bytecode executable passed
  as argument, -M prints the magic number expected by ocamlrun.
  (Sébastien Hinderer, review by Xavier Clerc and Damien Doligez)

- #1867: Remove the C plugins mechanism.
  (Xavier Leroy, review by David Allsopp, Damien Doligez, Sébastien Hinderer)

- #8627: Require SSE2 for 32-bit mingw port to generate correct code
  for caml_round with GCC 7.4.
  (David Allsopp, review by Xavier Leroy)

- #7676, #2144: Remove old GC heuristic
  (Damien Doligez, report and review by Alain Frisch)

* #1683: Change Marshal format to make Custom_tag objects store their
  length. Old versions of OCaml will no longer be able to parse new marshalled
  files containing custom blocks, but old files will still parse.
  (Stephen Dolan)

- #1723: Remove internal Meta.static_{alloc,free} primitives.
  (Stephen Dolan, review by Gabriel Scherer)

- #1895: Printexc.get_callstack would return only one frame in native
  code in threads other then the initial one
  (Valentin Gatien-Baron, review by Xavier Leroy)

- #1900, #7814: avoid exporting non-prefixed identifiers in the debug
  and instrumented runtimes.
  (Damien Doligez, report by Gabriel Scherer)

- #2079: Avoid page table lookup in Pervasives.compare with
  no-naked-pointers
  (Sam Goldman, review by Gabriel Scherer, David Allsopp, Stephen Dolan)

- #7829, #8585: Fix pointer comparisons in freelist.c (for 32-bit platforms)
  (David Allsopp and Damien Doligez)

- #8567, #8569: on ARM64, use 32-bit loads to access caml_backtrace_active
  (Xavier Leroy, review by Mark Shinwell and Greta Yorsh)

- #8568: Fix a memory leak in mmapped bigarrays
  (Damien Doligez, review by Xavier Leroy and Jérémie Dimino)

### Tools

- #2182: Split Emacs caml-mode as an independent project.
  (Christophe Troestler, review by Gabriel Scherer)

- #1865: support dark themes in Emacs, and clean up usage of
  deprecated Emacs APIs
  (Wilfred Hughes, review by Clément Pit-Claudel)

- #1590: ocamllex-generated lexers can be instructed not to update
  their lex_curr_p/lex_start_p fields, resulting in a significant
  performance gain when those fields are not required.
  (Alain Frisch, review by Jérémie Dimino)

- #7843, #2013: ocamldoc, better handling of {{!label}text} in the latex
  backend.
  (Florian Angeletti, review by Nicolás Ojeda Bär and Gabriel Scherer)

- #7844, #2040: Emacs, use built-in detection of comments,
  fixes an imenu crash.
  (Wilfred Hughes, review by Christophe Troestler)

- #7850: Emacs, use symbol boundaries in regular expressions,
  fixes an imenu crash.
  (Wilfred Hughes, review by Christophe Troestler)

- #1711: the new 'open' flag in OCAMLPARAM takes a comma-separated list of
  modules to open as if they had been passed via the command line -open flag.
  (Nicolás Ojeda Bär, review by Mark Shinwell)

- #2000: ocamdoc, extended support for "include module type of ..."
  (Florian Angeletti, review by Jérémie Dimino)

- #2045: ocamlmklib now supports options -args and -args0 to provide extra
  command-line arguments in a file.
  (Nicolás Ojeda Bär, review by Gabriel Scherer and Daniel Bünzli)

- #2189: change ocamldep Makefile-output to print each dependency
  on a new line, for more readable diffs of versioned dependencies.
  (Gabriel Scherer, review by Nicolás Ojeda Bär)

- #2223: ocamltest: fix the "bsd" and "not-bsd" built-in actions to
  recognize all BSD variants
  (Damien Doligez, review by Sébastien Hinderer and David Allsopp)

### Compiler distribution build system:

- #1776: add -no-install-bytecode-programs and related configure options to
  control (non-)installation of ".byte" executables.
  (Mark Shinwell, review by Sébastien Hinderer and Gabriel Scherer)

- #1777: add -no-install-source-artifacts and related configure options to
  control installation of .cmt, .cmti, .mli and .ml files.
  (Mark Shinwell, review by Nicolás Ojeda Bär and Sébastien Hinderer)

- #1781: cleanup of the manual's build process.
  (steinuil, review by Marcello Seri, Gabriel Scherer and Florian Angeletti)

- #1797: remove the deprecated Makefile.nt files.
  (Sébastien Hinderer, review by Nicolás Ojeda Bär)

- #1805: fix the bootstrap procedure and its documentation.
  (Sébastien Hinderer, Xavier Leroy and Damien Doligez; review by
  Gabriel Scherer)

- #1840: build system enhancements.
  (Sébastien Hinderer, review by David Allsopp, Xavier Leroy and
  Damien Doligez)

- #1852: merge runtime directories
  (Sébastien Hinderer, review by Xavier Leroy and Damien Doligez)

- #1854: remove the no longer defined BYTECCCOMPOPTS build variable.
  (Sébastien Hinderer, review by Damien Doligez)

- #2024: stop supporting obsolete platforms: Rhapsody (old beta
  version of MacOS X, BeOS, alpha*-*-linux*, mips-*-irix6*,
  alpha*-*-unicos, powerpc-*-aix, *-*-solaris2*, mips*-*-irix[56]*,
  i[3456]86-*-darwin[89].*, i[3456]86-*-solaris*, *-*-sunos* *-*-unicos.
  (Sébastien Hinderer, review by Xavier Leroy, Damien Doligez, Gabriel
  Scherer and Armaël Guéneau)

- #2053: allow unix, vmthreads and str not to be built.
  (David Allsopp, review by Sébastien Hinderer)

* #2059: stop defining OCAML_STDLIB_DIR in s.h.
  (Sébastien Hinderer, review by David Allsopp and Damien Doligez)

* #2066: remove the standard_runtime configuration variable.
  (Sébastien Hinderer, review by Xavier Leroy, Stephen Dolan and
  Damien Doligez)

* #2139: use autoconf to generate the compiler's configuration script
  (Sébastien Hinderer, review by Damien Doligez and David Allsopp)

- #2148: fix a parallel build bug involving CamlinternalLazy.
  (Stephen Dolan, review by Gabriel Scherer and Nicolás Ojeda Bär)

- #2264, #7904: the configure script now sets the Unicode handling mode
  under Windows according to the value of the variable WINDOWS_UNICODE_MODE. If
  WINDOWS_UNICODE_MODE is "ansi" then it is assumed to be the current code page
  encoding. If WINDOWS_UNICODE_MODE is "compatible" or empty or not set at all,
  then encoding is UTF-8 with code page fallback.
  (Nicolás Ojeda Bär, review by Sébastien Hinderer and David Allsopp)

- #2266: ensure Cygwin ports configure with `EXE=.exe`, or the compiler is
  unable to find the camlheader files (subtle regression of #2139/2041)
  (David Allsopp, report and review by Sébastien Hinderer)

- #7919, #2311: Fix assembler detection in configure
  (Sébastien Hinderer, review by David Allsopp)

- #2295: Restore support for bytecode target XLC/AIX/Power
  (Konstantin Romanov, review by Sébastien Hinderer and David Allsopp)

- #8528: get rid of the direct call to the C preprocessor in the testsuite
  (Sébastien Hinderer, review by David Allsopp)

- #7938, #8532: Fix alignment detection for ints on 32-bits platforms
  (Sébastien Hinderer, review by Xavier Leroy)

* #8533: Remove some unused configure tests
  (Stephen Dolan, review by David Allsopp and Sébastien Hinderer)

- #2207, #8604: Add opam files to allow pinning
  (Leo White, Greta Yorsh, review by Gabriel Radanne)

- #8616: configure: use variables rather than arguments for a few options
  (Sébastien Hinderer, review by David Allsopp, Gabriel Scherer and
  Damien Doligez)

- #8632: Correctly propagate flags for --with-pic in configure.
  (David Allsopp, review by Sébastien Hinderer and Damien Doligez)

- #8673: restore SpaceTime and libunwind support in configure script
  (Sébastien Hinderer, review by Damien Doligez)

### Internal/compiler-libs changes:

- #7918, #1703, #1944, #2213, #2257: Add the module
  Compile_common, which factorizes the common part in Compile and
  Optcompile. This also makes the pipeline more modular.
  (Gabriel Radanne, help from Gabriel Scherer and Valentin
   Gatien-Baron, review by Mark Shinwell and Gabriel Radanne,
   regression spotted by Clément Franchini)

- #292: use Menhir as the parser generator for the OCaml parser.
  Satellite GPRs: #1844, #1846, #1853, #1850, #1934, #2151,
  #2174
  (Gabriel Scherer, Nicolás Ojeda Bär, Frédéric Bour, Thomas Refis
   and François Pottier,
   review by Nicolás Ojeda Bär, Leo White and David Allsopp)

- #374: use Misc.try_finally for resource cleanup in the compiler
  codebase. This should fix the problem of catch-and-reraise `try .. with`
  blocks destroying backtrace information -- in the compiler.
  (François Bobot, help from Gabriel Scherer and Nicolás Ojeda Bär,
   review by Gabriel Scherer)

- #1148, #1287, #1288, #1874: significant improvements
  of the tools/check-typo script used over the files of the whole repository;
  contributors are now expected to check that check-typo passes on their
  pull requests; see CONTRIBUTING.md for more details.
  (David Allsopp, review by Damien Doligez and Sébastien Hinderer)

- #1610, #2252: Remove positions from paths
  (Leo White, review by Frédéric Bour and Thomas Refis)

- #1745: do not generalize the type of every sub-pattern,
  only of variables. (preliminary work for GADTs in or-patterns)
  (Thomas Refis, review by Leo White)

- #1909: unsharing pattern types (preliminary work for GADTs in or-patterns)
  (Thomas Refis, with help from Leo White, review by Jacques Garrigue)

- #1748: do not error when instantiating polymorphic fields in patterns.
  (Thomas Refis, review by Gabriel Scherer)

- #2317: type_let: be more careful generalizing parts of the pattern
  (Thomas Refis and Leo White, review by Jacques Garrigue)

- #1746: remove unreachable error variant: Make_seltype_nongen.
  (Florian Angeletti, review by Gabriel Radanne)

- #1747: type_cases: always propagate (preliminary work
  for GADTs in or-patterns)
  (Thomas Refis, review by Jacques Garrigue)

- #1811: shadow the polymorphic comparison in the middle-end
  (Xavier Clerc, review by Pierre Chambart)

- #1833: allow non-val payloads in CMM Ccatch handlers
  (Simon Fowler, review by Xavier Clerc)

- #1866: document the release process
  (Damien Doligez and Gabriel Scherer, review by Sébastien Hinderer,
   Perry E. Metzger, Xavier Leroy and David Allsopp)

- #1886: move the Location.absname reference to Clflags.absname
  (Armaël Guéneau, review by Jérémie Dimino)

- #1894: generalize highlight_dumb in location.ml to handle highlighting
  several locations
  (Armaël Guéneau, review by Gabriel Scherer)

- #1903: parsetree, add locations to all nodes with attributes
  (Gabriel Scherer, review by Thomas Refis)

- #1905: add check-typo-since to check the files changed
  since a given git reference
  (Gabriel Scherer, review by David Allsopp)

- #1910: improve the check-typo use of .gitattributes
  (Gabriel Scherer, review by David Allsopp and Damien Doligez)

- #1938: always check ast invariants after preprocessing
  (Florian Angeletti, review by Alain Frisch and Gabriel Scherer)

- #1941: refactor the command line parsing of ocamlcp and ocamloptp
  (Valentin Gatien-Baron, review by Florian Angeletti)

- #1948: Refactor Stdlib.Format. Notably, use Stdlib.Stack and Stdlib.Queue,
  and avoid exceptions for control flow.
  (Vladimir Keleshev, review by Nicolás Ojeda Bär and Gabriel Scherer)

* #1952: refactor the code responsible for displaying errors and warnings
  `Location.report_error` is removed, use `Location.print_report` instead
  (Armaël Guéneau, review by Thomas Refis)

- #7835, #1980, #8548, #8586: separate scope from stamp in idents and explicitly
  rescope idents when substituting signatures.
  (Thomas Refis, review by Jacques Garrigue and Leo White)

- #1996: expose Pprintast.longident to help compiler-libs users print
  Longident.t values.
  (Gabriel Scherer, review by Florian Angeletti and Thomas Refis)

- #2030: makefile targets to build AST files of sources
  for parser testing. See parsing/HACKING.adoc.
  (Gabriel Scherer, review by Nicolás Ojeda Bär)

* #2041: add a cache for looking up files in the load path
  (Jérémie Dimino, review by Alain Frisch and David Allsopp)

- #2047, #2269: a new type for unification traces
  (Florian Angeletti, report by Leo White (#2269),
   review by Thomas Refis and Gabriel Scherer)

- #2055: Add [Linearize.Lprologue].
  (Mark Shinwell, review by Pierre Chambart)

- #2056: Use [Backend_var] rather than [Ident] from [Clambda] onwards;
  use [Backend_var.With_provenance] for variables in binding position.
  (Mark Shinwell, review by Pierre Chambart)

- #2060: "Phantom let" support for the Clambda language.
  (Mark Shinwell, review by Vincent Laviron)

- #2065: Add [Proc.destroyed_at_reloadretaddr].
  (Mark Shinwell, review by Damien Doligez)

- #2070: "Phantom let" support for the Cmm language.
  (Mark Shinwell, review by Vincent Laviron)

- #2072: Always associate a scope to a type
  (Thomas Refis, review by Jacques Garrigue and Leo White)

- #2074: Correct naming of record field inside [Ialloc] terms.
  (Mark Shinwell, review by Jérémie Dimino)

- #2076: Add [Targetint.print].
  (Mark Shinwell)

- #2080: Add [Proc.dwarf_register_numbers] and
  [Proc.stack_ptr_dwarf_register_number].
  (Mark Shinwell, review by Bernhard Schommer)

- #2088: Add [Clambda.usymbol_provenance].
  (Mark Shinwell, review by Damien Doligez)

- #2152, #2517: refactorize the fixpoint to compute type-system
  properties of mutually-recursive type declarations.
  (Gabriel Scherer and Rodolphe Lepigre, review by Armaël Guéneau)

- #2156: propagate more type information through Lambda and Clambda
  intermediate language, as a preparation step for more future optimizations
  (Pierre Chambart and Alain Frisch, cross-reviewed by themselves)

- #2160: restore --disable-shared support and ensure testsuite runs correctly
  when compiled without shared library support.
  (David Allsopp, review by Damien Doligez and Sébastien Hinderer)

* #2173: removed TypedtreeMap
  (Thomas Refis, review by Gabriel Scherer)

- #7867: Fix #mod_use raising an exception for filenames with no
  extension.
  (Geoff Gole)

- #2100: Fix Unix.getaddrinfo when called on strings containing
  null bytes; it would crash the GC later on.
  (Armaël Guéneau, report and fix by Joe, review by Sébastien Hinderer)

- #7847, #2019: Fix an infinite loop that could occur when the
  (Menhir-generated) parser encountered a syntax error in a certain
  specific state.
  (François Pottier, report by Stefan Muenzel,
  review by Frédéric Bour, Thomas Refis, Gabriel Scherer)

- #1626: Do not allow recursive modules in `with module`
  (Leo White, review by Gabriel Radanne)

- #7726, #1676: Recursive modules, equi-recursive types and stack overflow
  (Jacques Garrigue, report by Jeremy Yallop, review by Leo White)

- #7723, #1698: Ensure `with module` and `with type` do not weaken
  module aliases.
  (Leo White, review by Gabriel Radanne and Jacques Garrigue)

- #1719: fix Pervasives.LargeFile functions under Windows.
  (Alain Frisch)

- #1739: ensure ocamltest waits for child processes to terminate on Windows.
  (David Allsopp, review by Sébastien Hinderer)

- #7554, #1751: Lambda.subst: also update debug event environments
  (Thomas Refis, review by Gabriel Scherer)

- #7238, #1825: in Unix.in_channel_of_descr and Unix.out_channel_of_descr,
  raise an error if the given file description is not suitable for
  character-oriented I/O, for example if it is a block device or a
  datagram socket.
  (Xavier Leroy, review by Jérémie Dimino and Perry E. Metzger)

- #7799, #1820: fix bug where Scanf.format_from_string could fail when
  the argument string contained characters that require escaping.
  (Gabriel Scherer and Nicolás Ojeda Bär, report by Guillaume Melquiond, review
  by Gabriel Scherer)

- #1843: ocamloptp was doing the wrong thing with option -inline-max-unroll.
  (Github user @poechsel, review by Nicolás Ojeda Bär).

- #1890: remove last use of Ctype.unroll_abbrev
  (Thomas Refis, report by Leo White, review by Jacques Garrigue)

- #1893: dev-branch only, warning 40(name not in scope) triggered spurious
  warnings 49(missing cmi) with -no-alias-deps.
  (Florian Angeletti, report by Valentin Gatien-Baron,
  review by Gabriel Scherer)

- #1912: Allow quoted strings, octal/unicode escape sequences and identifiers
  containing apostrophes in ocamllex actions and comments.
  (Pieter Goetschalckx, review by Damien Doligez)

- #7828, #1935: correct the conditions that generate warning 61,
  Unboxable_type_in_prim_decl
  (Stefan Muenzel)

- #1958: allow [module M(_:S) = struct end] syntax
  (Hugo Heuzard, review by Gabriel Scherer)

- #1970: fix order of floatting documentation comments in classes
  (Hugo Heuzard, review by Nicolás Ojeda Bär)

- #1977: [@@ocaml.warning "..."] attributes attached to type declarations are
  no longer ignored.
  (Nicolás Ojeda Bär, review by Gabriel Scherer)

- #7830, #1987: fix ocamldebug crash when printing a value in the scope of
  an `open` statement for which the `.cmi` is not available.
  (Nicolás Ojeda Bär, report by Jocelyn Sérot, review by Gabriel Scherer)

- #7854, #2062: fix an issue where the wrong locale may be used when using
  the legacy ANSI encoding under Windows.
  (Nicolás Ojeda Bär, report by Tiphaine Turpin)

- #2083: Fix excessively aggressive float unboxing and introduce similar fix
  as a preventative measure for boxed int unboxing.
  (Thomas Refis, Mark Shinwell, Leo White)

- #2130: fix printing of type variables with a quote in their name
  (Alain Frisch, review by Armaël Guéneau and Gabriel Scherer,
  report by Hugo Heuzard)

- #2131: fix wrong calls to Env.normalize_path on non-module paths
  (Alain Frisch, review by Jacques Garrigue)

- #2175: Apply substitution to all modules when packing
  (Leo White, review by Gabriel Scherer)

- #2220: Remove duplicate process management code in
  otherlibs/threads/unix.ml
  (Romain Beauxis, review by Gabriel Scherer and Alain Frisch)

- #2231: Env: always freshen persistent signatures before using them
  (Thomas Refis and Leo White, review by Gabriel Radanne)

- #7851, #8570: Module type of allows to transform a malformed
  module type into a vicious signature, breaking soundness
  (Jacques Garrigue, review by Leo White)

- #7923, #2259: fix regression in FlexDLL bootstrapped build caused by
  refactoring the root Makefile for Dune in #2093)
  (David Allsopp, report by Marc Lasson)

- #7929, #2261: Subst.signature: call cleanup_types exactly once
  (Thomas Refis, review by Gabriel Scherer and Jacques Garrigue,
  report by Daniel Bünzli and Jon Ludlam)

- #8550, #8552: Soundness issue with class generalization
  (Jacques Garrigue, review by Leo White and Thomas Refis,
  report by Jeremy Yallop)

OCaml 4.07.1 (4 October 2018)
-----------------------------

### Bug fixes:

- #7815, #1896: major GC crash with first-fit policy
  (Stephen Dolan and Damien Doligez, report by Joris Giovannangeli)

* #7818, #2051: Remove local aliases in functor argument types,
  to prevent the aliasing of their target.
  (Jacques Garrigue, report by mandrykin, review by Leo White)

- #7820, #1897: Fix Array.of_seq. This function used to apply a circular
  permutation of one cell to the right on the sequence.
  (Thierry Martinez, review by Nicolás Ojeda Bär)

- #7821, #1908: make sure that the compilation of extension
  constructors doesn't cause the compiler to load more cmi files
  (Jérémie Dimino, review by Gabriel Scherer)

- #7824, #1914: subtype_row: filter out absent fields when row is closed
  (Leo White and Thomas Refis, report by talex, review by Jacques Garrigue)

- #1915: rec_check.ml is too permissive for certain class declarations.
  (Alban Reynaud with Gabriel Scherer, review by Jeremy Yallop)

- #7833, #1946: typecore: only 1k existential per match, not 100k
  (Thomas Refis, report by Jerome Simeon, review by Jacques Garrigue)

- #7838: -principal causes assertion failure in type checker
  (Jacques Garrigue, report by Markus Mottl, review by Thomas Refis)

OCaml 4.07.0 (10 July 2018)
---------------------------

(Changes that can break existing programs are marked with a "*")

### Language features:

- #6023, #1648: Allow type-based selection of GADT constructors.
  (Thomas Refis and Leo White, review by Jacques Garrigue and Gabriel Scherer)

- #1546: Allow empty variants.
  (Runhang Li, review by Gabriel Radanne and Jacques Garrigue)

### Standard library:

- #4170, #1674: add the constant `Float.pi`.
  (Christophe Troestler, review by Damien Doligez)

- #6139, #1685: Move the Bigarray module to the standard library. Keep the
  bigarray library as on overlay adding the deprecated map_file functions.
  (Jérémie Dimino, review by Mark Shinwell)

- #7528, #1500: add a Format.pp_set_geometry function to avoid memory
  effects in set_margin and set_max_indent.
  (Florian Angeletti, review by Richard Bonichon, Gabriel Radanne,
   Gabriel Scherer and Pierre Weis)

- #7690, #1528: fix the float_of_string function for hexadecimal floats
  with very large values of the exponent.
  (Olivier Andrieu)

- #1002: add a new `Seq` module defining a list-of-thunks style iterator.
  Also add `{to,of}_seq` to several standard modules.
  (Simon Cruanes, review by Alain Frisch and François Bobot)

* #1010: pack all standard library modules into a single module Stdlib
  which is the default opened module (Stdlib itself includes Pervasives) to free
  up the global namespace for other standard libraries, while still allowing any
  OCaml standard library module to be referred to as Stdlib.Module). This is
  implemented efficiently using module aliases (prefixing all modules with
  Stdlib__, e.g. Stdlib__string).
  (Jérémie Dimino, David Allsopp and Florian Angeletti, review by David Allsopp
   and Gabriel Radanne)

- #1637: String.escaped is faster and does not allocate when called with a
  string that does not contain any characters needing to be escaped.
  (Alain Frisch, review by Xavier Leroy and Gabriel Scherer)

- #1638: add a Float module.
  (Nicolás Ojeda Bär, review by Alain Frisch and Jeremy Yallop)

- #1697: Tune [List.init] tailrec threshold so that it does not stack
  overflow when compiled with the Js_of_ocaml backend.
  (Hugo Heuzard, reviewed by Gabriel Scherer)

### Other libraries:

- #7745, #1629: Graphics.open_graph displays the correct window title on
  Windows again (fault introduced by 4.06 Unicode changes).
  (David Allsopp)

* #1406: Unix.isatty now returns true in the native Windows ports when
  passed a file descriptor connected to a Cygwin PTY. In particular, compiler
  colors for the native Windows ports now work under Cygwin/MSYS2.
  (Nicolás Ojeda Bär, review by Gabriel Scherer, David Allsopp, Xavier Leroy)

- #1451: [getpwuid], [getgrgid], [getpwnam], [getgrnam] now raise Unix error
  instead of returning [Not_found] when interrupted by a signal.
  (Arseniy Alekseyev, review by Mark Shinwell and Xavier Leroy)

- #1477: raw_spacetime_lib can now be used in bytecode.
  (Nicolás Ojeda Bär, review by Mark Shinwell)

- #1533: (a) The implementation of Thread.yield for system thread
  now uses nanosleep(1) for enabling better preemption.
  (b) Thread.delay is now an alias for Unix.sleepf.
  (Jacques-Henri Jourdan, review by Xavier Leroy and David Allsopp)

### Compiler user-interface and warnings:

- #7663, #1694: print the whole cycle and add a reference to the manual in
  the unsafe recursive module evaluation error message.
  (Florian Angeletti, report by Matej Košík, review by Gabriel Scherer)

- #1166: In OCAMLPARAM, an alternative separator can be specified as
  first character (instead of comma) in the set ":|; ,"
  (Fabrice Le Fessant)

- #1358: Fix usage warnings with no mli file.
  (Leo White, review by Alain Frisch)

- #1428: give a non dummy location for warning 49 (no cmi found).
  (Valentin Gatien-Baron)

- #1491: Improve error reporting for ill-typed applicative functor
  types, F(M).t.
  (Valentin Gatien-Baron, review by Florian Angeletti and Gabriel Radanne)

- #1496: Refactor the code printing explanation for unification type errors,
  in order to avoid duplicating pattern matches.
  (Armaël Guéneau, review by Florian Angeletti and Gabriel Scherer)

- #1505: Add specific error messages for unification errors involving
  functions of type "unit -> _".
  (Arthur Charguéraud and Armaël Guéneau, with help from Leo White, review by
  Florian Angeletti and Gabriel Radanne)

- #1510: Add specific explanation for unification errors caused by type
  constraints propagated by keywords (such as if, while, for...).
  (Armaël Guéneau and Gabriel Scherer, original design by Arthur Charguéraud,
  review by Frédéric Bour, Gabriel Radanne and Alain Frisch)

- #1515: honor the BUILD_PATH_PREFIX_MAP environment variable
  to enable reproducible builds.
  (Gabriel Scherer, with help from Ximin Luo, review by Damien Doligez)

- #1534: Extend the warning printed when (*) is used, adding a hint to
  suggest using ( * ) instead.
  (Armaël Guéneau, with help and review from Florian Angeletti and Gabriel
  Scherer)

- #1552, #1577: do not warn about ambiguous variables in guards
  (warning 57) when the ambiguous values have been filtered by
  a previous clause.
  (Gabriel Scherer and Thomas Refis, review by Luc Maranget)

- #1554: warnings 52 and 57: fix reference to manual detailed explanation.
  (Florian Angeletti, review by Thomas Refis and Gabriel Scherer)

- #1618: add the -dno-unique-ids and -dunique-ids compiler flags.
  (Sébastien Hinderer, review by Leo White and Damien Doligez)

- #1649: change compilation order of toplevel definitions, so that some
  warnings emitted by the bytecode compiler appear more in-order than before.
  (Luc Maranget, advice and review by Damien Doligez)

- #1806: add linscan to OCAMLPARAM options.
  (Raja Boujbel)

### Code generation and optimizations:

- #7630, #1401: Faster compilation of large modules with Flambda.
  (Pierre Chambart, report by Emilio Jesús Gallego Arias,
  Pierre-Marie Pédrot and Paul Steckler, review by Gabriel Scherer
  and Leo White)

- #7630, #1455: Disable CSE for the initialization function.
  (Pierre Chambart, report by Emilio Jesús Gallego Arias,
   review by Gabriel Scherer and Xavier Leroy)

- #1370: Fix code duplication in Cmmgen.
  (Vincent Laviron, with help from Pierre Chambart,
   reviews by Gabriel Scherer and Luc Maranget)

- #1486: ARM 32-bit port: add support for ARMv8 in 32-bit mode,
  a.k.a. AArch32.
  For this platform, avoid ITE conditional instruction blocks and use
  simpler IT blocks instead.
  (Xavier Leroy, review by Mark Shinwell)

- #1487: Treat negated float comparisons more directly.
  (Leo White, review by Xavier Leroy)

- #1573: emitcode: merge events after instructions reordering.
  (Thomas Refis and Leo White, with help from David Allsopp, review by Frédéric
  Bour)

- #1606: Simplify the semantics of Lambda.free_variables and Lambda.subst,
  including some API changes in bytecomp/lambda.mli.
  (Pierre Chambart, review by Gabriel Scherer)

- #1613: ensure that set-of-closures are processed first so that other
  entries in the let-rec symbol do not get dummy approximations.
  (Leo White and Xavier Clerc, review by Pierre Chambart)

* #1617: Make string/bytes distinguishable in the bytecode.
  (Hugo Heuzard, reviewed by Nicolás Ojeda Bär)

- #1627: Reduce cmx sizes by sharing variable names (Flambda only).
  (Fu Yong Quah, Leo White, review by Xavier Clerc)

- #1665: reduce the size of cmx files in classic mode by dropping the
  bodies of functions that will not be inlined.
  (Fu Yong Quah, review by Leo White and Pierre Chambart)

- #1666: reduce the size of cmx files in classic mode by dropping the
  bodies of functions that cannot be reached from the module block.
  (Fu Yong Quah, review by Leo White and Pierre Chambart)

- #1686: Turn off by default flambda invariants checks.
  (Pierre Chambart)

- #1707: Add [Closure_origin.t] to trace inlined functions to prevent
  infinite loops from repeatedly inlining copies of the same function.
  (Fu Yong Quah)

- #1740: make sure startup.o is always linked in when using
  "-output-complete-obj". Previously, it was always linked in only on some
  platforms, making this option unusable on platforms where it wasn't.
  (Jérémie Dimino, review by Sébastien Hinderer and Xavier Leroy)

### Runtime system:

- #515 #676 #7173: Add a public C API for weak arrays and
  ephemerons. Update the documentation for a 4.03 change: finalisation
  functions are now run before the erasure of the corresponding
  values.
  (François Bobot and Jacques-Henri Jourdan, review by Mark Shinwell,
   Damien Doligez and Frédéric Bour)

- #6411, #1535: don't compile everything with -static-libgcc on mingw32,
  only dllbigarray.dll and libbigarray.a. Allows the use of C++ libraries which
  raise exceptions.
  (David Allsopp)

- #7100, #1476: trigger a minor GC when custom blocks accumulate
  in minor heap.
  (Alain Frisch, report by talex, review by Damien Doligez, Leo White,
  Gabriel Scherer)

- #1431: remove ocamlrun dependencies on curses/terminfo/termcap C library.
  (Xavier Leroy, review by Daniel Bünzli)

- #1478: The Spacetime profiler now works under Windows (but it is not yet
  able to collect profiling information from C stubs).
  (Nicolás Ojeda Bär, review by Xavier Leroy, Mark Shinwell)

- #1483: fix GC freelist accounting for chunks larger than the maximum block
  size.
  (David Allsopp and Damien Doligez)

- #1526: install the debug and instrumented runtimes
  (lib{caml,asm}run{d,i}.a).
  (Gabriel Scherer, reminded by Julia Lawall)

- #1563: simplify implementation of LSRINT and ASRINT.
  (Max Mouratov, review by Frédéric Bour)

- #1644: remove caml_alloc_float_array from the bytecode primitives list
  (it's a native code primitive).
  (David Allsopp)

- #1701: fix missing root bug in #1476.
  (Mark Shinwell)

- #1752: do not alias function arguments to sigprocmask.
  (Anil Madhavapeddy)

- #1753: avoid potential off-by-one overflow in debugger socket path length.
  (Anil Madhavapeddy)

### Tools:

- #7643, #1377: ocamldep, fix an exponential blowup in presence of nested
  structures and signatures, e.g. "include struct … include(struct … end) … end"
  (Florian Angeletti, review by Gabriel Scherer, report by Christophe Raffalli)

- #7687, #1653: deprecate -thread option,
  which is equivalent to -I +threads.
  (Nicolás Ojeda Bär, report by Daniel Bünzli)

- #7710: `ocamldep -sort` should exit with nonzero code in case of
  cyclic dependencies.
  (Xavier Leroy, report by Mantis user baileyparker)

- #1537: boot/ocamldep is no longer included in the source distribution;
  boot/ocamlc -depend can be used in its place.
  (Nicolás Ojeda Bär, review by Xavier Leroy and Damien Doligez)

- #1585: optimize output of "ocamllex -ml".
  (Alain Frisch, review by Frédéric Bour and Gabriel Scherer)

- #1667: add command-line options -no-prompt, -no-version, -no-time,
  -no-breakpoint-message and -topdirs-path to ocamldebug.
  (Sébastien Hinderer, review by Damien Doligez)

- #1695: add the -null-crc command-line option to ocamlobjinfo.
  (Sébastien Hinderer, review by David Allsopp and Gabriel Scherer)

- #1710: ocamldoc, improve the 'man' rendering of subscripts and
  superscripts.
  (Gabriel Scherer)

- #1771: ocamldebug, avoid out of bound access.
  (Thomas Refis)

### Manual and documentation:

- #7613: minor rewording of the "refutation cases" paragraph.
  (Florian Angeletti, review by Jacques Garrigue)

- #7647, #1384: emphasize ocaml.org website and forum in README.
  (Yawar Amin, review by Gabriel Scherer)

- #7698, #1545: improve wording in OCaml manual in several places,
  mostly in Chapter 1.  This addresses the easier changes suggested in the PR.
  (Jim Fehrle, review by Florian Angeletti and David Allsopp)

- #1540: manual, decouple verbatim and toplevel style in code examples.
  (Florian Angeletti, review by Gabriel Scherer)

- #1556: manual, add a consistency test for manual references inside
  the compiler source code.
  (Florian Angeletti, review by Gabriel Scherer)

- #1647: manual, subsection on record and variant disambiguation.
  (Florian Angeletti, review by Alain Frisch and Gabriel Scherer)

- #1702: manual, add a signature mode for code examples.
  (Florian Angeletti, review by Gabriel Scherer)

- #1741: manual, improve typesetting and legibility in HTML output.
  (steinuil, review by Gabriel Scherer)

- #1757: style the html manual, changing type and layout.
  (Charles Chamberlain, review by Florian Angeletti, Xavier Leroy,
  Gabriel Radanne, Perry E. Metzger, and Gabriel Scherer)

- #1765: manual, ellipsis in code examples.
  (Florian Angeletti, review and suggestion by Gabriel Scherer)

- #1767: change html manual to use relative font sizes.
  (Charles Chamberlain, review by Daniel Bünzli, Perry E. Metzger,
  Josh Berdine, and Gabriel Scherer)

- #1779: integrate the Bigarray documentation into the main manual.
  (Perry E. Metzger, review by Florian Angeletti and Xavier Clerc)

### Type system:

- #7611, #1491: reject the use of generative functors as applicative.
  (Valentin Gatien-Baron)

- #7706, #1565: in recursive value declarations, track
  static size of locally-defined variables.
  (Gabriel Scherer, review by Jeremy Yallop and Leo White, report by Leo White)

- #7717, #1593: in recursive value declarations, don't treat
  unboxed constructor size as statically known.
  (Jeremy Yallop, report by Pierre Chambart, review by Gabriel Scherer)

- #7767, #1712: restore legacy treatment of partially-applied
  labeled functions in 'let rec' bindings.
  (Jeremy Yallop, report by Ivan Gotovchits, review by Gabriel Scherer)

* #7787, #1652, #1743: Don't remove module aliases in `module type of`
  and `with module`.
  The old behaviour can be obtained using the `[@remove_aliases]` attribute.
  (Leo White and Thomas Refis, review by Jacques Garrigue)

- #1468: Do not enrich type_decls with incoherent manifests.
  (Thomas Refis and Leo White, review by Jacques Garrigue)

- #1469: Use the information from [@@immediate] annotations when
  computing whether a type can be [@@unboxed].
  (Damien Doligez, report by Stephan Muenzel, review by Alain Frisch)

- #1513: Allow compilation units to shadow sub-modules of Pervasives.
  For instance users can now use a largeFile.ml file in their project.
  (Jérémie Dimino, review by Nicolás Ojeda Bär, Alain Frisch and Gabriel
  Radanne)

- #1516: Allow float array construction in recursive bindings
  when configured with -no-flat-float-array.
  (Jeremy Yallop, report by Gabriel Scherer)

- #1583: propagate refined ty_arg to Parmatch checks.
  (Thomas Refis, review by Jacques Garrigue)

- #1609: Changes to ambivalence scope tracking.
  (Thomas Refis and Leo White, review by Jacques Garrigue)

- #1628: Treat reraise and raise_notrace as nonexpansive.
  (Leo White, review by Alain Frisch)

* #1778: Fix Soundness bug with non-generalized type variable and
  local modules.  This is the same bug as #7414, but using local
  modules instead of non-local ones.
  (Leo White, review by Jacques Garrigue)

### Compiler distribution build system:

- #5219, #1680, #1877: use 'install' instead of 'cp'
  in install scripts.
  (Gabriel Scherer, review by Sébastien Hinderer and Valentin Gatien-Baron)

- #7679: make sure .a files are erased before calling ar rc, otherwise
  leftover .a files from an earlier compilation may contain unwanted modules.
  (Xavier Leroy)

- #1571: do not perform architecture tests on 32-bit platforms, allowing
  64-bit back-ends to use 64-bit specific constructs.
  (Xavier Clerc, review by Damien Doligez)

### Internal/compiler-libs changes:

- #7738, #1624: Asmlink.reset also resets lib_ccobjs/ccopts.
  (Cedric Cellier, review by Gabriel Scherer)

- #1488, #1560: Refreshing parmatch.
  (Gabriel Scherer and Thomas Refis, review by Luc Maranget)

- #1502: more command line options for expect tests.
  (Florian Angeletti, review by Gabriel Scherer)

- #1511: show code at error location in expect-style tests,
  using new Location.show_code_at_location function.
  (Gabriel Scherer and Armaël Guéneau,
   review by Valentin Gatien-Baron and Damien Doligez)

- #1519, #1532, #1570: migrate tests to ocamltest.
  (Sébastien Hinderer, review by Gabriel Scherer, Valentin Gatien-Baron
  and Nicolás Ojeda Bär)

- #1520: more robust implementation of Misc.no_overflow_mul.
  (Max Mouratov, review by Xavier Leroy)

- #1557: Organise and simplify translation of primitives.
  (Leo White, review by François Bobot and Nicolás Ojeda Bär)

- #1567: register all idents relevant for reraise.
  (Thomas Refis, review by Alain Frisch and Frédéric Bour)

- #1586: testsuite: 'make promote' for ocamltest tests.
  (The new "-promote" option for ocamltest is experimental
  and subject to change/removal).
  (Gabriel Scherer)

- #1619: expect_test: print all the exceptions, even the unexpected ones.
  (Thomas Refis, review by Jérémie Dimino)

- #1621: expect_test: make sure to not use the installed stdlib.
  (Jérémie Dimino, review by Thomas Refis)

- #1646: add ocamldoc test to ocamltest and
  migrate ocamldoc tests to ocamltest.
  (Florian Angeletti, review by Sébastien Hinderer)

- #1663: refactor flambda specialise/inlining handling.
  (Leo White and Xavier Clerc, review by Pierre Chambart)

- #1679: remove Pbittest from primitives in lambda.
  (Hugo Heuzard, review by Mark Shinwell)

* #1704: Make Ident.t abstract and immutable.
  (Gabriel Radanne, review by Mark Shinwell)

- #1699: Clean up Maps and Sets throughout the compiler.
  Remove the Tbl module in favor of dedicated Maps.
  (Gabriel Radanne, review by Mark Shinwell)

### Bug fixes:

- #4499, #1479: Use native Windows API to implement Sys.getenv,
  Unix.getenv and Unix.environment under Windows.
  (Nicolás Ojeda Bär, report by Alain Frisch, review by David Allsopp, Xavier
  Leroy)

- #5250, #1435: on Cygwin, when ocamlrun searches the path
  for a bytecode executable file, skip directories and other
  non-regular files, like other Unix variants do.
  (Xavier Leroy)

- #6394, #1425: fix fatal_error from Parmatch.get_type_path.
  (Virgile Prevosto, review by David Allsopp, Thomas Refis and Jacques Garrigue)

* #6604, #931: Only allow directives with filename and at the beginning of
  the line.
  (Tadeu Zagallo, report by Roberto Di Cosmo,
   review by Hongbo Zhang, David Allsopp, Gabriel Scherer, Xavier Leroy)

- #7138, #7701, #1693: Keep documentation comments
  even in empty structures and signatures.
  (Leo White, Florian Angeletti, report by Anton Bachin)

- #7178, #7253, #7796, #1790: Make sure a function
  registered with "at_exit" is executed only once when the program exits.
  (Nicolás Ojeda Bär and Xavier Leroy, review by Max Mouratov)

- #7391, #1620: Do not put a dummy method in object types.
  (Thomas Refis, review by Jacques Garrigue)

- #7660, #1445: Use native Windows API to implement Unix.utimes in order to
  avoid unintended shifts of the argument timestamp depending on DST setting.
  (Nicolás Ojeda Bär, review by David Allsopp, Xavier Leroy)

- #7668: -principal is broken with polymorphic variants.
  (Jacques Garrigue, report by Jun Furuse)

- #7680, #1497: Incorrect interaction between Matching.for_let and
  Simplif.simplify_exits.
  (Alain Frisch, report and review by Vincent Laviron)

- #7682, #1495: fix [@@unboxed] for records with 1 polymorphic field.
  (Alain Frisch, report by Stéphane Graham-Lengrand, review by Gabriel Scherer)

- #7695, #1541: Fatal error: exception Ctype.Unify(_) with field override
  (Jacques Garrigue, report by Nicolás Ojeda Bär)

- #7704, #1564: use proper variant tag in non-exhaustiveness warning.
  (Jacques Garrigue, report by Thomas Refis)

- #7711, #1581: Internal typechecker error triggered by a constraint on
   self type in a class type.
  (Jacques Garrigue, report and review by Florian Angeletti)

- #7712, #1576: assertion failure with type abbreviations.
  (Thomas Refis, report by Michael O'Connor, review by Jacques Garrigue)

- #7747: Type checker can loop infinitely and consume all computer memory.
  (Jacques Garrigue, report by kantian)

- #7751, #1657: The toplevel prints some concrete types as abstract.
  (Jacques Garrigue, report by Matej Košík)

- #7765, #1718: When unmarshaling bigarrays, protect against integer
  overflows in size computations.
  (Xavier Leroy, report by Maximilian Tschirschnitz,
   review by Gabriel Scherer)

- #7760, #1713: Exact selection of lexing engine, that is
  correct "Segfault in ocamllex-generated code using 'shortest'".
  (Luc Maranget, Frédéric Bour, report by Stephen Dolan,
  review by Gabriel Scherer)

- #7769, #1714: calls to Stream.junk could, under some conditions, be
  ignored when used on streams based on input channels.
  (Nicolás Ojeda Bär, report by Michael Perin, review by Gabriel Scherer)

- #7793, #1766: the toplevel #use directive now accepts sequences of ';;'
  tokens. This fixes a bug in which certain files accepted by the compiler were
  rejected by ocamldep.
  (Nicolás Ojeda Bär, report by Hugo Heuzard, review by Hugo Heuzard)

- #1517: More robust handling of type variables in mcomp.
  (Leo White and Thomas Refis, review by Jacques Garrigue)

- #1530, #1574: testsuite, fix 'make parallel' and 'make one DIR=...'
  to work on ocamltest-based tests.
  (Runhang Li and Sébastien Hinderer, review by Gabriel Scherer)

- #1550, #1555: Make pattern matching warnings more robust
  to ill-typed columns.
  (Thomas Refis, with help from Gabriel Scherer and Luc Maranget)

- #1614: consider all bound variables when inlining, fixing a compiler
  fatal error.
  (Xavier Clerc, review by Pierre Chambart, Leo White)

- #1622: fix bug in the expansion of command-line arguments under Windows
  which could result in some elements of Sys.argv being truncated in some cases.
  (Nicolás Ojeda Bär, review by Sébastien Hinderer)

- #1623: Segfault on Windows 64 bits when expanding wildcards in arguments.
  (Marc Lasson, review by David Allsopp, Alain Frisch, Sébastien Hinderer,
   Xavier Leroy, Nicolás Ojeda Bär)

- #1661: more precise principality warning regarding record fields
  disambiguation.
  (Thomas Refis, review by Leo White)

- #1687: fix bug in the printing of short functor types "(S1 -> S2) -> S3".
  (Pieter Goetschalckx, review by Gabriel Scherer)

- #1722: Scrape types in Typeopt.maybe_pointer.
  (Leo White, review by Thomas Refis)

- #1755: ensure that a bigarray is never collected while reading complex
  values.
  (Xavier Clerc, Mark Shinwell and Leo White, report by Chris Hardin,
  reviews by Stephen Dolan and Xavier Leroy)

- #1764: in byterun/memory.c, struct pool_block, use C99 flexible arrays
  if available.
  (Xavier Leroy, review by Max Mouratov)

- #1774: ocamlopt for ARM could generate VFP loads and stores with bad
  offsets, rejected by the assembler.
  (Xavier Leroy, review by Mark Shinwell)

- #1808: handle `[@inlined]` attributes under a module constraint.
  (Xavier Clerc, review by Leo White)

- #1810: use bit-pattern comparison when meeting float approximations.
  (Xavier Clerc, report by Christophe Troestler, review by Nicolás Ojeda Bär
   and Gabriel Scherer)

- #1835: Fix off-by-one errors in Weak.get_copy and Weak.blit.
  (KC Sivaramakrishnan)

- #1849: bug in runtime function generic_final_minor_update()
  that could lead to crashes when Gc.finalise_last is used.
  (report and fix by Yuriy Vostrikov, review by François Bobot)


OCaml 4.06.1 (16 Feb 2018):
---------------------------

### Bug fixes:

- #7661, #1459: fix faulty compilation of patterns
  using extensible variants constructors
  (Luc Maranget, review by Thomas Refis and Gabriel Scherer, report
  by Abdelraouf Ouadjaout and Thibault Suzanne)

- #7702, #1553: refresh raise counts when inlining a function
  (Vincent Laviron, Xavier Clerc, report by Cheng Sun)

- #7704, #1559: Soundness issue with private rows and pattern-matching
  (Jacques Garrigue, report by Jeremy Yallop, review by Thomas Refis)

- #7705, #1558: add missing bounds check in Bigarray.Genarray.nth_dim.
  (Nicolás Ojeda Bär, report by Jeremy Yallop, review by Gabriel Scherer)

- #7713, #1587: Make pattern matching warnings more robust
  to ill-typed columns; this is a backport of #1550 from 4.07+dev
  (Thomas Refis, review by Gabriel Scherer, report by Andreas Hauptmann)

- #1470: Don't commute negation with float comparison
  (Leo White, review by Xavier Leroy)

- #1538: Make pattern matching compilation more robust to ill-typed columns
  (Gabriel Scherer and Thomas Refis, review by Luc Maranget)

OCaml 4.06.0 (3 Nov 2017):
--------------------------

(Changes that can break existing programs are marked with a "*")

### Language features:

- #6271, #7529, #1249: Support "let open M in ..."
  in class expressions and class type expressions.
  (Alain Frisch, reviews by Thomas Refis and Jacques Garrigue)

- #792: fix limitations of destructive substitutions, by
  allowing "S with type t := type-expr",
  "S with type M.t := type-expr", "S with module M.N := path"
  (Valentin Gatien-Baron, review by Jacques Garrigue and Leo White)

* #1064, #1392: extended indexing operators, add a new class of
  user-defined indexing operators, obtained by adding at least
  one operator character after the dot symbol to the standard indexing
  operators: e,g ".%()", ".?[]", ".@{}<-":
    let ( .%() ) = List.nth in [0; 1; 2].%(1)
  After this change, functions or methods with an explicit polymorphic type
  annotation and of which the first argument is optional now requires a space
  between the dot and the question mark,
  e.g. "<f:'a.?opt:int->unit>" must now be written "<f:'a. ?opt:int->unit>".
  (Florian Angeletti, review by Damien Doligez and Gabriel Radanne)

- #1118: Support inherited field in object type expression
    type t = < m : int >
    type u = < n : int; t; k : int >
  (Runhang Li, review by Jeremy Yallop, Leo White, Jacques Garrigue,
   and Florian Angeletti)

* #1232: Support Unicode character escape sequences in string
  literals via the \u{X+} syntax. These escapes are substituted by the
  UTF-8 encoding of the Unicode character.
  (Daniel Bünzli, review by Damien Doligez, Alain Frisch, Xavier
  Leroy and Leo White)

- #1247: M.(::) construction for expressions
  and patterns (plus fix printing of (::) in the toplevel)
  (Florian Angeletti, review by Alain Frisch, Gabriel Scherer)

* #1252: The default mode is now safe-string, can be overridden
  at configure time or at compile time.
  (See #1386 below for the configure-time options)
  This breaks the code that uses the 'string' type as mutable
  strings (instead of Bytes.t, introduced by 4.02 in 2014).
  (Damien Doligez)

* #1253: Private extensible variants
  This change breaks code relying on the undocumented ability to export
  extension constructors for abstract type in signature. Briefly,
    module type S = sig
      type t
      type t += A
    end
   must now be written
    module type S = sig
      type t = private ..
      type t += A
   end
  (Leo White, review by Alain Frisch)

- #1333: turn off warning 40 by default
  (Constructor or label name used out of scope)
  (Leo White)

- #1348: accept anonymous type parameters in `with` constraints:
    S with type _ t = int
  (Valentin Gatien-Baron, report by Jeremy Yallop)

### Type system

- #2642, #1225: unique names for weak type variables
    # ref [];;
    - : '_weak1 list ref = {contents = []}
  (Florian Angeletti, review by Frédéric Bour, Jacques Garrigue,
   Gabriel Radanne and Gabriel Scherer)

* #6738, #7215, #7231, #556: Add a new check that 'let rec'
  bindings are well formed.
  (Jeremy Yallop, reviews by Stephen Dolan, Gabriel Scherer, Leo
   White, and Damien Doligez)

- #1142: Mark assertions nonexpansive, so that 'assert false'
  can be used as a placeholder for a polymorphic function.
  (Stephen Dolan)

### Standard library:

- #8223, #7309, #1026: Add update to maps. Allows to update a
  binding in a map or create a new binding if the key had no binding
    val update: key -> ('a option -> 'a option) -> 'a t -> 'a t
  (Sébastien Briais, review by Daniel Bünzli, Alain Frisch and
  Gabriel Scherer)

- #7515, #1147: Arg.align now optionally uses the tab character '\t' to
  separate the "unaligned" and "aligned" parts of the documentation string. If
  tab is not present, then space is used as a fallback. Allows to have spaces in
  the unaligned part, which is useful for Tuple options.
  (Nicolás Ojeda Bär, review by Alain Frisch and Gabriel Scherer)

* #615: Format, add symbolic formatters that output symbolic
  pretty-printing items. New fields have been added to the
  formatter_out_functions record, thus this change will break any code building
  such record from scratch.
  When building Format.formatter_out_functions values redefining the out_spaces
  field, "{ fmt_out_funs with out_spaces = f; }" should be replaced by
  "{ fmt_out_funs with out_spaces = f; out_indent = f; }" to maintain the old
  behavior.
  (Richard Bonichon and Pierre Weis, review by Alain Frisch, original request by
  Spiros Eliopoulos in #506)

* #943: Fixed the divergence of the Pervasives module between the stdlib
  and threads implementations.  In rare circumstances this can change the
  behavior of existing applications: the implementation of Pervasives.close_out
  used when compiling with thread support was inconsistent with the manual.
  It will now not suppress exceptions escaping Pervasives.flush anymore.
  Developers who want the old behavior should use Pervasives.close_out_noerr
  instead.  The stdlib implementation, used by applications not compiled
  with thread support, will now only suppress Sys_error exceptions in
  Pervasives.flush_all.  This should allow exceedingly unlikely assertion
  exceptions to escape, which could help reveal bugs in the standard library.
  (Markus Mottl, review by Hezekiah M. Carty, Jérémie Dimino, Damien Doligez,
  Alain Frisch, Xavier Leroy, Gabriel Scherer and Mark Shinwell)

- #1034: List.init : int -> (int -> 'a) -> 'a list
  (Richard Degenne, review by David Allsopp, Thomas Braibant, Florian
  Angeletti, Gabriel Scherer, Nathan Moreau, Alain Frisch)

- #1091 Add the Uchar.{bom,rep} constants.
  (Daniel Bünzli, Alain Frisch)

- #1091: Add Buffer.add_utf_{8,16le,16be}_uchar to encode Uchar.t
  values to the corresponding UTF-X transformation formats in Buffer.t
  values.
  (Daniel Bünzli, review by Damien Doligez, Max Mouratov)

- #1175: Bigarray, add a change_layout function to each Array[N]
  submodules.
  (Florian Angeletti)

* #1306: In the MSVC and Mingw ports, "Sys.rename src dst" no longer fails if
  file "dst" exists, but replaces it with file "src", like in the other ports.
  (Xavier Leroy)

- #1314: Format, use the optional width information
  when formatting a boolean: "%8B", "%-8B" for example
  (Xavier Clerc, review by Gabriel Scherer)

- c9cc0f25138ce58e4f4e68c4219afe33e2a9d034: Resurrect tabulation boxes
  in module Format. Rewrite/extend documentation of tabulation boxes.
  (Pierre Weis)

### Other libraries:

- #7564, #1211: Allow forward slashes in the target of symbolic links
  created by Unix.symlink under Windows.
  (Nicolás Ojeda Bär, review by David Allsopp)

* #7640, #1414: reimplementation of Unix.execvpe to fix issues
  with the 4.05 implementation.  The main issue is that the current
  directory was always searched (last), even if the current directory
  is not listed in the PATH.
  (Xavier Leroy, report by Louis Gesbert and Arseniy Alekseyev,
   review by Ivan Gotovchits)

- #997, #1077: Deprecate Bigarray.*.map_file and add Unix.map_file as a
  first step towards moving Bigarray to the stdlib
  (Jérémie Dimino and Xavier Leroy)

* #1178: remove the Num library for arbitrary-precision arithmetic.
  It now lives as a separate project https://github.com/ocaml/num
  with an OPAM package called "num".
  (Xavier Leroy)

- #1217: Restrict Unix.environment in privileged contexts; add
  Unix.unsafe_environment.
  (Jeremy Yallop, review by Mark Shinwell, Nicolás Ojeda Bär,
  Damien Doligez and Hannes Mehnert)

- #1321: Reimplement Unix.isatty on Windows. It no longer returns true for
  the null device.
  (David Allsopp)

### Compiler user-interface and warnings:

- #7361, #1248: support "ocaml.warning" in all attribute contexts, and
  arrange so that "ocaml.ppwarning" is correctly scoped by surrounding
  "ocaml.warning" attributes
  (Alain Frisch, review by Florian Angeletti and Thomas Refis)

- #7444, #1138: trigger deprecation warning when a "deprecated"
  attribute is hidden by signature coercion
  (Alain Frisch, report by bmillwood, review by Leo White)

- #7472: ensure .cmi files are created atomically,
  to avoid corruption of .cmi files produced simultaneously by a run
  of ocamlc and a run of ocamlopt.
  (Xavier Leroy, from a suggestion by Gerd Stolpmann)

* #7514, #1152: add -dprofile option, similar to -dtimings but
  also displays memory allocation and consumption.
  The corresponding addition of a new compiler-internal
  Profile module may affect some users of
  compilers-libs/ocamlcommon (by creating module conflicts).
  (Valentin Gatien-Baron, report by Gabriel Scherer)

- #7620, #1317: Typecore.force_delayed_checks does not run with -i option
  (Jacques Garrigue, report by Jun Furuse)

- #7624: handle warning attributes placed on let bindings
  (Xavier Clerc, report by dinosaure, review by Alain Frisch)

- #896: "-compat-32" is now taken into account when building .cmo/.cma
  (Hugo Heuzard)

- #948: the compiler now reports warnings-as-errors by prefixing
  them with "Error (warning ..):", instead of "Warning ..:" and
  a trailing "Error: Some fatal warnings were triggered" message.
  (Valentin Gatien-Baron, review by Alain Frisch)

- #1032: display the output of -dtimings as a hierarchy
  (Valentin Gatien-Baron, review by Gabriel Scherer)

- #1114, #1393, #1429: refine the (ocamlc -config) information
  on C compilers: the variables `{bytecode,native}_c_compiler` are deprecated
  (the distinction is now mostly meaningless) in favor of a single
  `c_compiler` variable combined with `ocaml{c,opt}_cflags`
  and `ocaml{c,opt}_cppflags`.
  (Sébastien Hinderer, Jeremy Yallop, Gabriel Scherer, review by
   Adrien Nader and David Allsopp)

* #1189: allow MSVC ports to use -l option in ocamlmklib
  (David Allsopp)

- #1332: fix ocamlc handling of "-output-complete-obj"
  (François Bobot)

- #1336: -thread and -vmthread option information is propagated to
  PPX rewriters.
  (Jun Furuse, review by Alain Frisch)

### Code generation and optimizations:

- #5324, #375: An alternative Linear Scan register allocator for
  ocamlopt, activated with the -linscan command-line flag. This
  allocator represents a trade-off between worse generated code
  performance for higher compilation speed (especially interesting in
  some cases graph coloring is necessarily quadratic).
  (Marcell Fischbach and Benedikt Meurer, adapted by Nicolás Ojeda Bär, review
  by Nicolás Ojeda Bär and Alain Frisch)

- #6927, #988: On macOS, when compiling bytecode stubs, plugins,
  and shared libraries through -output-obj, generate dylibs instead of
  bundles.
  (whitequark)

- #7447, #995: incorrect code generation for nested recursive bindings
  (Leo White and Jeremy Yallop, report by Stephen Dolan)

- #7501, #1089: Consider arrays of length zero as constants
  when using Flambda.
  (Pierre Chambart, review by Mark Shinwell and Leo White)

- #7531, #1162: Erroneous code transformation at partial applications
  (Mark Shinwell)

- #7614, #1313: Ensure that inlining does not depend on the order
  of symbols (flambda)
  (Leo White, Xavier Clerc, report by Alex, review by Gabriel Scherer
  and Pierre Chambart)

- #7616, #1339: don't warn on mutation of zero size blocks.
  (Leo White)

- #7631, #1355: "-linscan" option crashes ocamlopt
  (Xavier Clerc, report by Paul Steckler)

- #7642, #1411: ARM port: wrong register allocation for integer
  multiply on ARMv4 and ARMv5; possible wrong register allocation for
  floating-point multiply and add on VFP and for floating-point
  negation and absolute value on soft FP emulation.
  (Xavier Leroy, report by Stéphane Glondu and Ximin Luo,
   review and additional sightings by Mark Shinwell)

* #659: Remove support for SPARC native code generation
  (Mark Shinwell)

- #850: Optimize away some physical equality
  (Pierre Chambart, review by Mark Shinwell and Leo White)

- #856: Register availability analysis
  (Mark Shinwell, Thomas Refis, review by Pierre Chambart)

- #1143: tweaked several allocation functions in the runtime by
  checking for likely conditions before unlikely ones and eliminating
  some redundant checks.
  (Markus Mottl, review by Alain Frisch, Xavier Leroy, Gabriel Scherer,
  Mark Shinwell and Leo White)

- #1183: compile curried functors to multi-argument functions
  earlier in the compiler pipeline; correctly propagate [@@inline]
  attributes on such functors; mark functor coercion veneers as
  stubs.
  (Mark Shinwell, review by Pierre Chambart and Leo White)

- #1195: Merge functions based on partiality rather than
  Parmatch.irrefutable.
  (Leo White, review by Thomas Refis, Alain Frisch and Gabriel Scherer)

- #1215: Improve compilation of short-circuit operators
  (Leo White, review by Frédéric Bour and Mark Shinwell)

- #1250: illegal ARM64 assembly code generated for large combined allocations
  (report and initial fix by Steve Walk, review and final fix by Xavier Leroy)

- #1271: Don't generate Ialloc instructions for closures that exceed
  Max_young_wosize; instead allocate them on the major heap.  (Related
  to #1250.)
  (Mark Shinwell)

- #1294: Add a configure-time option to remove the dynamic float array
  optimization and add a floatarray type to let the user choose when to
  flatten float arrays. Note that float-only records are unchanged: they
  are still optimized by unboxing their fields.
  (Damien Doligez, review by Alain Frisch and Mark Shinwell)

- #1304: Mark registers clobbered by PLT stubs as destroyed across
  allocations.
  (Mark Shinwell, Xavier Clerc, report and initial debugging by
  Valentin Gatien-Baron)

- #1323: make sure that frame tables are generated in the data
  section and not in the read-only data section, as was the case
  before in the PPC and System-Z ports.  This avoids relocations in
  the text segment of shared libraries and position-independent
  executables generated by ocamlopt.
  (Xavier Leroy, review by Mark Shinwell)

- #1330: when generating dynamically-linkable code on AArch64, always
  reference symbols (even locally-defined ones) through the GOT.
  (Mark Shinwell, review by Xavier Leroy)

### Tools:

- #8395, #973: tools/check-symbol-names checks for globally
  linked names not namespaced with caml_
  (Stephen Dolan)

- #6928, #1103: ocamldoc, do not introduce an empty <h1> in index.html
  when no -title has been provided
  (Pierre Boutillier)

- #7048: ocamldoc, in -latex mode, don't escape Latin-1 accented letters
  (Xavier Leroy, report by Hugo Herbelin)

* #7351: ocamldoc, use semantic tags rather than <br> tags in the html
  backend
  (Florian Angeletti, request and review by Daniel Bünzli )

* #7352, #7353: ocamldoc, better paragraphs in html output
  (Florian Angeletti, request by Daniel Bünzli)

* #7363, #830: ocamldoc, start heading levels at {1 not {2 or {6.
  This change modifies the mapping between ocamldoc heading level and
  html heading level, breaking custom css style for ocamldoc.
  (Florian Angeletti, request and review by Daniel Bünzli)

* #7478, #1037: ocamldoc, do not use as a module preamble documentation
  comments that occur after the first module element. This change may break
  existing documentation. In particular, module preambles must now come before
  any `open` statement.
  (Florian Angeletti, review by David Allsopp and report by Daniel Bünzli)

- #7521, #1159: ocamldoc, end generated latex file with a new line
  (Florian Angeletti)

- #7575, #1219: Switch compilers from -no-keep-locs
  to -keep-locs by default: produced .cmi files will contain locations.
  This provides better error messages. Note that, as a consequence,
  .cmi digests now depend on the file path as given to the compiler.
  (Daniel Bünzli)

- #7610, #1346: caml.el (the Emacs editing mode) was cleaned up
  and made compatible with Emacs 25.
  (Stefan Monnier, Christophe Troestler)

- #7635, #1383: ocamldoc, add an identifier to module
  and module type elements
  (Florian Angeletti, review by Yawar Amin and Gabriel Scherer)

- #681, #1426: Introduce ocamltest, a new test driver for the
  OCaml compiler testsuite
  (Sébastien Hinderer, review by Damien Doligez)

- #1012: ocamlyacc, fix parsing of raw strings and nested comments, as well
  as the handling of ' characters in identifiers.
  (Demi Marie Obenour)

- #1045: ocamldep, add a "-shared" option to generate dependencies
  for native plugin files (i.e. .cmxs files)
  (Florian Angeletti, suggestion by Sébastien Hinderer)

- #1078: add a subcommand "-depend" to "ocamlc" and "ocamlopt",
  to behave as ocamldep. Should be used mostly to replace "ocamldep" in the
  "boot" directory to reduce its size in the future.
  (Fabrice Le Fessant)

- #1036: ocamlcmt (tools/read_cmt) is installed, converts .cmt to .annot
  (Fabrice Le Fessant)

- #1180: Add support for recording numbers of direct and indirect
  calls over the lifetime of a program when using Spacetime profiling
  (Mark Shinwell)

- #1457, ocamldoc: restore label for exception in the latex backend
  (omitted since 4.04.0)
  (Florian Angeletti, review by Gabriel Scherer)

### Toplevel:

- #7570: remove unusable -plugin option from the toplevel
  (Florian Angeletti)

- #1041: -nostdlib no longer ignored by toplevel.
  (David Allsopp, review by Xavier Leroy)

- #1231: improved printing of unicode texts in the toplevel,
  unless OCAMLTOP_UTF_8 is set to false.
  (Florian Angeletti, review by Daniel Bünzli, Xavier Leroy and
   Gabriel Scherer)

- #1688: Fix printing of -0.
  (Nicolás Ojeda Bär, review by Jérémie Dimino)

### Runtime system:

* #3771, #153, #1200, #1357, #1362, #1363, #1369, #1398,
  #1446, #1448: Unicode support for the Windows runtime.
  (ygrek, Nicolás Ojeda Bär, review by Alain Frisch, David Allsopp, Damien
  Doligez)

* #7594, #1274, #1368: String_val now returns 'const char*', not
  'char*' when -safe-string is enabled at configure time.  New macro Bytes_val
  for accessing bytes values.
  (Jeremy Yallop, reviews by Mark Shinwell and Xavier Leroy)

- #71: The runtime can now be shut down gracefully by means of the new
  caml_shutdown and caml_startup_pooled functions. The new 'c' flag in
  OCAMLRUNPARAM enables shutting the runtime properly on process exit.
  (Max Mouratov, review and discussion by Damien Doligez, Gabriel Scherer,
  Mark Shinwell, Thomas Braibant, Stephen Dolan, Pierre Chambart,
  François Bobot, Jacques Garrigue, David Allsopp, and Alain Frisch)

- #938, #1170, #1289: Stack overflow detection on 64-bit Windows
  (Olivier Andrieu, tweaked by David Allsopp)

- #1070, #1295: enable gcc typechecking for caml_alloc_sprintf,
  caml_gc_message. Make caml_gc_message a variadic function. Fix many
  caml_gc_message format strings.
  (Olivier Andrieu, review and 32bit fix by David Allsopp)

- #1073: Remove statically allocated compare stack.
  (Stephen Dolan)

- #1086: in Sys.getcwd, just fail instead of calling getwd()
  if HAS_GETCWD is not set.
  (Report and first fix by Sebastian Markbåge, final fix by Xavier Leroy,
   review by Mark Shinwell)

- #1269: Remove 50ms delay at exit for programs using threads
  (Valentin Gatien-Baron, review by Stephen Dolan)

* #1309: open files with O_CLOEXEC (or equivalent) in caml_sys_open, thus
  unifying the semantics between Unix and Windows and also eliminating race
  condition on Unix.
  (David Allsopp, report by Andreas Hauptmann)

- #1326: Enable use of CFI directives in AArch64 and ARM runtime
  systems' assembly code (asmrun/arm64.S).  Add CFI directives to enable
  unwinding through [caml_c_call] and [caml_call_gc] with correct termination
  of unwinding at [main].
  (Mark Shinwell, review by Xavier Leroy and Gabriel Scherer, with thanks
  to Daniel Bünzli and Fu Yong Quah for testing)

- #1338: Add "-g" for bytecode runtime system compilation
  (Mark Shinwell)

* #1416, #1444: switch the Windows 10 Console to UTF-8 encoding.
  (David Allsopp, reviews by Nicolás Ojeda Bär and Xavier Leroy)

### Manual and documentation:

- #6548: remove obsolete limitation in the description of private
  type abbreviations
  (Florian Angeletti, suggestion by Leo White)

- #6676, #1110: move record notation to tutorial
  (Florian Angeletti, review by Gabriel Scherer)

- #6676, #1112: move local opens to tutorial
  (Florian Angeletti)

- #6676, #1153: move overriding class definitions to reference
  manual and tutorial
  (Florian Angeletti)

- #6709: document the associativity and precedence level of
  pervasive operators
  (Florian Angeletti, review by David Allsopp)

- #7254, #1096: Rudimentary documentation of ocamlnat
  (Mark Shinwell)

- #7281, #1259: fix .TH macros in generated manpages
  (Olaf Hering)

- #7507: Align the description of the printf conversion
  specification "%g" with the ISO C90 description.
  (Florian Angeletti, suggestion by Armaël Guéneau)

- #7551, #1194 : make the final ";;" potentially optional in
  caml_example
  (Florian Angeletti, review and suggestion by Gabriel Scherer)

- #7588, #1291: make format documentation predictable
  (Florian Angeletti, review by Gabriel Radanne)

- #7604: Minor Ephemeron documentation fixes
  (Miod Vallat, review by Florian Angeletti)

- #594: New chapter on polymorphism troubles:
  weakly polymorphic types, polymorphic recursion,and higher-ranked
  polymorphism.
  (Florian Angeletti, review by Damien Doligez, Gabriel Scherer,
   and Gerd Stolpmann)

- #1187: Minimal documentation for compiler plugins
  (Florian Angeletti)

- #1202: Fix Typos in comments as well as basic grammar errors.
  (JP Rodi, review and suggestions by David Allsopp, Max Mouratov,
  Florian Angeletti, Xavier Leroy, Mark Shinwell and Damien Doligez)

- #1220: Fix "-keep-docs" option in ocamlopt manpage
  (Etienne Millon)

### Compiler distribution build system:

- #6373, #1093: Suppress trigraph warnings from macOS assembler
  (Mark Shinwell)

- #7639, #1371: fix configure script for correct detection of
  int64 alignment on Mac OS X 10.13 (High Sierra) and above; fix bug in
  configure script relating to such detection.
  (Mark Shinwell, report by John Whitington, review by Xavier Leroy)

- #558: enable shared library and natdynlink support on more Linux
  platforms
  (Felix Janda, Mark Shinwell)

* #1104: remove support for the NeXTStep platform
  (Sébastien Hinderer)

- #1130: enable detection of IBM XL C compiler (one need to run configure
  with "-cc <path to xlc compiler>"). Enable shared library support for
  bytecode executables on AIX/xlc (tested on AIX 7.1, XL C 12).
  To enable 64-bit, run both "configure" and "make world" with OBJECT_MODE=64.
  (Konstantin Romanov, Enrique Naudon)

- #1203: speed up the manual build by using ocamldoc.opt
  (Gabriel Scherer, review by Florian Angeletti)

- #1214: harden config/Makefile against '#' characters in PREFIX
  (Gabriel Scherer, review by David Allsopp and Damien Doligez)

- #1216: move Compplugin and friends from BYTECOMP to COMP
  (Leo White, review by Mark Shinwell)

* #1242: disable C plugins loading by default
  (Alexey Egorov)

- #1275: correct configure test for Spacetime availability
  (Mark Shinwell)

- #1278: discover presence of <sys/shm.h> during configure for afl runtime
  (Hannes Mehnert)

- #1386: provide configure-time options to fine-tune the safe-string
  options and default settings changed by #1252.

  The previous configure option -safe-string is now
  renamed -force-safe-string.

  At configure-time, -force-safe-string forces all module to use
  immutable strings (this disables the per-file, compile-time
  -unsafe-string option). The new default-(un)safe-string options
  let you set the default choice for the per-file compile-time
  option. (The new #1252 behavior corresponds to having
  -default-safe-string, while 4.05 and older had
  -default-unsafe-string).

  (Gabriel Scherer, review by Kate Deplaix and Damien Doligez)

- #1409: Fix to enable NetBSD/powerpc to work.
  (Håvard Eidnes)

### Internal/compiler-libs changes:

- #6826, #828, #834: improve compilation time for open
  (Alain Frisch, review by Frédéric Bour and Jacques Garrigue)

- #7127, #454, #1058: in toplevel, print bytes and strip
  strings longer than the size specified by the "print_length" directive
  (Fabrice Le Fessant, initial PR by Junsong Li)

- #406: remove polymorphic comparison for Types.constructor_tag in compiler
  (Dwight Guth, review by Gabriel Radanne, Damien Doligez, Gabriel Scherer,
   Pierre Chambart, Mark Shinwell)

- #1119: Change Set (private) type to inline records.
  (Albin Coquereau)

* #1127: move config/{m,s}.h to byterun/caml and install them.
  User code should not have to include them directly since they are
  included by other header files.
  Previously {m,s}.h were not installed but they were substituted into
  caml/config.h; they are now just #include-d by this file. This may
  break some scripts relying on the (unspecified) presence of certain
  #define in config.h instead of m.h and s.h -- they can be rewritten
  to try to grep those files if they exist.
  (Sébastien Hinderer)

- #1281: avoid formatter flushes inside exported printers in Location
  (Florian Angeletti, review by Gabriel Scherer)

### Bug fixes:

- #5927: Type equality broken for conjunctive polymorphic variant tags
  (Jacques Garrigue, report by Leo White)

- #6329, #1437: Introduce padding word before "data_end" symbols
  to ensure page table tests work correctly on an immediately preceding
  block of zero size.
  (Mark Shinwell, review by Xavier Leroy)

- #6587: only elide Pervasives from printed type paths in unambiguous context
  (Florian Angeletti and Jacques Garrigue)

- #6934: nonrec misbehaves with GADTs
  (Jacques Garrigue, report by Markus Mottl)

- #7070, #1139: Unexported values can cause non-generalisable variables
  error
  (Leo White)

- #7261: Warn on type constraints in GADT declarations
  (Jacques Garrigue, report by Didier Le Botlan)

- #7321: Private type in signature clashes with type definition via
  functor instantiation
  (Jacques Garrigue, report by Markus Mottl)

- #7372, #834: fix type-checker bug with GADT and inline records
  (Alain Frisch, review by Frédéric Bour and Jacques Garrigue)

- #7344: Inconsistent behavior with type annotations on let
  (Jacques Garrigue, report by Leo White)

- #7468: possible GC problem in caml_alloc_sprintf
  (Xavier Leroy, discovery by Olivier Andrieu)

- #7496: Fixed conjunctive polymorphic variant tags do not unify
  with themselves
  (Jacques Garrigue, report by Leo White)

- #7506: pprintast ignores attributes in tails of a list
  (Alain Frisch, report by Kenichi Asai and Gabriel Scherer)

- #7513: List.compare_length_with mishandles negative numbers / overflow
  (Fabrice Le Fessant, report by Jeremy Yallop)

- #7519: Incorrect rejection of program due to faux scope escape
  (Jacques Garrigue, report by Markus Mottl)

- #7540, #1179: Fixed setting of breakpoints within packed modules
  for ocamldebug
  (Hugo Herbelin, review by Gabriel Scherer, Damien Doligez)

- #7543: short-paths printtyp can fail on packed type error messages
  (Florian Angeletti)

- #7553, #1191: Prevent repeated warnings with recursive modules.
  (Leo White, review by Josh Berdine and Alain Frisch)

- #7563, #1210: code generation bug when a module alias and
  an extension constructor have the same name in the same module
  (Gabriel Scherer, report by Manuel Fähndrich,
   review by Jacques Garrigue and Leo White)

- #7591, #1257: on x86-64, frame table is not 8-aligned
  (Xavier Leroy, report by Mantis user "voglerr", review by Gabriel Scherer)

- #7601, #1320: It seems like a hidden non-generalized type variable
  remains in some inferred signatures, which leads to strange errors
  (Jacques Garrigue, report by Mandrikin)

- #7609: use-after-free memory corruption if a program debugged
  under ocamldebug calls Pervasives.flush_all
  (Xavier Leroy, report by Paul Steckler, review by Gabriel Scherer)

- #7612, #1345: afl-instrumentation bugfix for classes.
  (Stephen Dolan, review by Gabriel Scherer and David Allsopp)

- #7617, #7618, #1318: Ambiguous (mistakenly) type escaping the
  scope of its equation
  (Jacques Garrigue, report by Thomas Refis)

- #7619, #1387: position of the optional last semi-column not included
  in the position of the expression (same behavior as for lists)
  (Christophe Raffalli, review by Gabriel Scherer)

- #7638: in the Windows Mingw64 port, multithreaded programs compiled
  to bytecode could crash when raising an exception from C code.
  This looks like a Mingw64 issue, which we work around with GCC builtins.
  (Xavier Leroy)

- #7656, #1423: false 'unused type/constructor/value' alarms
  in the 4.06 development version
  (Alain Frisch, review by Jacques Garrigue, report by Kate Deplaix)

- #7657, #1424: ensures correct call-by-value semantics when
  eta-expanding functions to eliminate optional arguments
  (Alain Frisch, report by sliquister, review by Leo White and Jacques
  Garrigue)

- #7658, #1439: Fix Spacetime runtime system compilation with
  -force-safe-string
  (Mark Shinwell, report by Christoph Spiel, review by Gabriel Scherer)

- #1155: Fix a race condition with WAIT_NOHANG on Windows
  (Jérémie Dimino and David Allsopp)

- #1199: Pretty-printing formatting cleanup in pprintast
  (Ethan Aubin, suggestion by Gabriel Scherer, review by David Allsopp,
  Florian Angeletti, and Gabriel Scherer)

- #1223: Fix corruption of the environment when using -short-paths
  with the toplevel.
  (Leo White, review by Alain Frisch)

- #1243: Fix pprintast for #... infix operators
  (Alain Frisch, report by Omar Chebib)

- #1324: ensure that flambda warning are printed only once
  (Xavier Clerc)

- #1329: Prevent recursive polymorphic variant names
  (Jacques Garrigue, fix suggested by Leo White)

- #1308: Only treat pure patterns as inactive
  (Leo White, review by Alain Frisch and Gabriel Scherer)

- #1390: fix the [@@unboxed] type check to accept parametrized types
  (Leo White, review by Damien Doligez)

- #1407: Fix raw_spacetime_lib
  (Leo White, review by Gabriel Scherer and Damien Doligez)

OCaml 4.05.0 (13 Jul 2017):
---------------------------

(Changes that can break existing programs are marked with a "*")

### Language features:

### Code generation and optimizations:

- #7201, #954: Correct wrong optimisation of "0 / <expr>"
  and "0 mod <expr>" in the case when <expr> was a non-constant
  evaluating to zero
  (Mark Shinwell, review by Gabriel Scherer, Leo White and Xavier Leroy)

- #7357, #832: Improve compilation time for toplevel
  include(struct ... end : sig ... end)
  (Alain Frisch, report by Hongbo Zhang, review by Jacques Garrigue)

- #7533, #1173: Correctly perform side effects for certain
  cases of "/" and "mod"
  (Mark Shinwell, report by Jan Mitgaard)

- #504: Instrumentation support for fuzzing with afl-fuzz.
  (Stephen Dolan, review by Alain Frisch, Pierre Chambart, Mark
  Shinwell, Gabriel Scherer and Damien Doligez)

- #863, #1068, #1069: Optimise matches with constant
  results to lookup tables.
  (Stephen Dolan, review by Gabriel Scherer, Pierre Chambart,
  Mark Shinwell, and bug report by Gabriel Scherer)

- #1150: Fix typo in arm64 assembler directives
  (KC Sivaramakrishnan)

### Runtime system:

- #2784, #953: Add caml_startup_exn
  (Mark Shinwell)

- #7423, #946: expose new exception-raising functions
  `void caml_{failwith,invalid_argument}_value(value msg)`
  in addition to
  `void caml_{failwith,invalid_argument}(char const *msg)`.
  The previous functions would not free their message argument, so
  were inconvient for dynamically-allocated messages; the messages
  passed to the new functions are handled by the garbage collector.
  (Gabriel Scherer, review by Mark Shinwell, request by Immanuel Litzroth)

- #7557, #1213: More security for getenv
  (Damien Doligez, reports by Seth Arnold and Eric Milliken, review by
  Xavier Leroy, David Allsopp, Stephen Dolan, Hannes Mehnert)

- #795: remove 256-character limitation on Sys.executable_name
  (Xavier Leroy)

- #891: Use -fno-builtin-memcmp when building runtime with gcc.
  (Leo White)

### Type system:

- #6608, #901: unify record types when overriding all fields
  (Tadeu Zagallo and Gabriel Scherer, report by Jeremy Yallop,
  review by David Allsopp, Jacques Garrigue)

* #7414, #929: Soundness bug with non-generalized type variables and
  functors.
  (compatibility: some code using module-global mutable state will
   fail at compile-time and is fixed by adding extra annotations;
   see the Mantis and Github discussions.)
  (Jacques Garrigue, report by Leo White)

### Compiler user-interface and warnings:

- #7050, #748 #843 #864: new `-args/-args0 <file>` parameters to
  provide extra command-line arguments in a file -- see documentation.
  User programs may implement similar options using the new `Expand`
  constructor of the `Arg` module.
  (Bernhard Schommer, review by Jérémie Dimino, Gabriel Scherer
   and Damien Doligez, discussion with Alain Frisch and Xavier Leroy,
   feature request from the Coq team)

- #7137, #960: "-open" command line flag now accepts
  a module path (not a module name)
  (Arseniy Alekseyev and Leo White)

- #7172, #970: add extra (ocamlc -config) options
  int_size, word_size, ext_exe
  (Gabriel Scherer, request by Daniel Bünzli)

- #7315, #736: refine some error locations
  (Gabriel Scherer and Alain Frisch, report by Matej Košík)

- #7473, #1025: perform proper globbing for command-line arguments on
  Windows
  (Jonathan Protzenko)

- #7479: make sure "ocamlc -pack" is only given .cmo and .cmi files,
  and that "ocamlopt -pack" is only given .cmx and .cmi files.
  (Xavier Leroy)

- #796: allow compiler plugins to declare their own arguments.
  (Fabrice Le Fessant)

- #829: better error when opening a module aliased to a functor
  (Alain Frisch)

- #911: ocamlc/ocamlopt do not pass warnings-related options to C
  compiler when called to compile third-party C source files
  (Sébastien Hinderer, review by Adrien Nader and David Allsopp)

- #915: fix -dsource (pprintast.ml) bugs
  (Runhang Li, review by Alain Frisch)

* #933: ocamlopt -p now reports an error on platforms that do not
  support profiling with gprof; dummy profiling libraries are no longer
  installed on such platforms.
  This can be tested with ocamlopt -config
  (Sébastien Hinderer)

- #1009: "ocamlc -c -linkall" and "ocamlopt -c -linkall" can now be used
  to set the "always link" flag on individual compilation units.  This
  controls linking with finer granularity than "-a -linkall", which sets
  the "always link" flag on all units of the given library.
  (Xavier Leroy)

- #1015: add option "-plugin PLUGIN" to ocamldep too. Use compilerlibs
  to build ocamldep. Add option "-depend" to ocamlc/ocamlopt to behave
  as ocamldep. Remove any use of ocamldep to build the distribution.
  (Fabrice Le Fessant)

- #1027: various improvements to -dtimings, mostly including time
  spent in subprocesses like preprocessors
  (Valentin Gatien-Baron, review by Gabriel Scherer)

- #1098: the compiler now takes the boolean "OCAML_COLOR" environment
  variable into account if "-color" is not provided.  This allows users
  to override the default behaviour without modifying invocations of ocaml
  manually.
  (Hannes Mehnert, Guillaume Bury,
   review by Daniel Bünzli, Gabriel Scherer, Damien Doligez)

### Standard library:

- #6975, #902: Truncate function added to stdlib Buffer module
  (Dhruv Makwana, review by Alain Frisch and Gabriel Scherer)

- #7279, #710: `Weak.get_copy` `Ephemeron.*_copy` doesn't copy
  custom blocks anymore
  (François Bobot, Alain Frisch, report by Martin R. Neuhäußer,
  review by Thomas Braibant and Damien Doligez)

* #7500, #1081: Remove Uchar.dump
  (Daniel Bünzli)

- #760: Add a functions List.compare_lengths and
  List.compare_length_with to avoid full list length computations
  (Fabrice Le Fessant, review by Leo White, Josh Berdine and Gabriel Scherer)

- #778: Arg: added option Expand that allows to expand a string
  argument to a string array of new arguments
  (Bernhard Schommer, review by Gabriel Scherer and Jérémie Dimino)

- #849: Expose a Spacetime.enabled value
  (Leo White)

- #885: Option-returning variants of stdlib functions
  (Alain Frisch, review by David Allsopp and Bart Jacobs)

- #869: Add find_first, find_first_opt, find_last, find_last_opt to
  maps and sets.  Find the first or last binding or element
  satisfying a monotonic predicate.
  (Gabriel de Perthuis, with contributions from Alain Frisch, review by
  Hezekiah M. Carty and Simon Cruanes, initial report by Gerd Stolpmann)

- #875: Add missing functions to ArrayLabels, BytesLabels,
  ListLabels, MoreLabels, StringLabels so they are compatible with
  non-labeled counterparts. Also add missing @@ocaml.deprecated attributes
  in StringLabels and BytesLabels.
  (Roma Sokolov, review by Gabriel Scherer, Jacques Garrigue,
   Gabriel Radanne, Alain Frisch)

- #999: Arg, do not repeat the usage message thrice when reporting an error
  (this was a regression in 4.03)
  (Florian Angeletti, review by Gabriel Scherer)

- #1042: Fix escaping of command-line arguments in
  Unix.create_process{,_env} under Windows.  Arguments with tabs should now
  be received verbatim by the child process.
  (Nicolás Ojeda Bär, Andreas Hauptmann review by Xavier Leroy)

### Debugging and profiling:

- #7258: ocamldebug's "install_printer" command had problems with
  module aliases
  (Xavier Leroy)

- #378: Add [Printexc.raise_with_backtrace] to raise an exception using
  an explicit backtrace
  (François Bobot, review by Gabriel Scherer, Xavier Leroy, Damien Doligez,
   Frédéric Bour)

### Manual and documentation:

- #6597, #1030: add forward references to language extensions
  that extend non-terminal symbols in the language reference section.
  (Florian Angeletti, review by Gabriel Scherer)

- #7497, #1095: manual, enable numbering for table of contents
  (Florian Angeletti, request by Daniel Bünzli)

- #7539, #1181: manual, update dead links in ocamldoc chapter
  (Florian Angeletti)

- #633: manpage and manual documentation for the `-opaque` option
  (Konstantin Romanov, Gabriel Scherer, review by Mark Shinwell)

- #751, #925: add a HACKING.adoc file to contain various
  tips and tricks for people hacking on the repository. See also
  CONTRIBUTING.md for advice on sending contributions upstream.
  (Gabriel Scherer and Gabriel Radanne, review by David Allsopp,
  inspired by John Whitington)

- #916: new tool lintapidiff, use it to update the manual with
  @since annotations for API changes introduced between 4.00-4.05.
  (Edwin Török, review by Gabriel Scherer, discussion with Alain Frisch,
   David Allsopp, Sébastien Hinderer, Damien Doligez and Xavier Leroy)

- #939: activate the caml_example environment in the language
  extensions section of the manual. Convert some existing code
  examples to this format.
  (Florian Angeletti)

- #1082: clarify that the use of quoted string for preprocessed
  foreign quotations still requires the use of an extension node
  [%foo ...] to mark non-standard interpretation.
  (Gabriel Scherer, request by Matthew Wahab in #1066,
   review by Florian Angeletti)

### Other libraries:

- #7158: Event.sync, Mutex.create, Condition.create cause too many GCs.
  The fix is to no longer consider mutexes and condition variables
  as rare kernel resources.
  (Xavier Leroy)

- #7264: document the different behaviors of Unix.lockf under POSIX
  and under Win32.
  (Xavier Leroy, report by David Allsopp)

- #7339, #787: Support the '0 dimension' case for bigarrays
  (see Bigarray documentation)
  (Laurent Mazare,
   review by Gabriel Scherer, Alain Frisch and Hezekiah M. Carty)

* #7342, #797: fix Unix.read on pipes with no data left on Windows
  it previously raised an EPIPE error, it now returns 0 like other OSes
  (Jonathan Protzenko, review by Andreas Hauptmann and Damien Doligez)

- #650: in the Unix library, add `?cloexec:bool` optional arguments to
  functions that create file descriptors (`dup`, `dup2`, `pipe`, `socket`,
  `socketpair`, `accept`).  Implement these optional arguments in the
  most atomic manner provided by the operating system to set (or clear)
  the close-on-exec flag at the same time the file descriptor is created,
  reducing the risk of race conditions with `exec` or `create_process`
  calls running in other threads, and improving security.  Also: add a
  `O_KEEPEXEC` flag for `openfile` by symmetry with `O_CLOEXEC`.
  (Xavier Leroy, review by Mark Shinwell, David Allsopp and Alain Frisch,
   request by Romain Beauxis)

- #996: correctly update caml_top_of_stack in systhreads
  (Fabrice Le Fessant)

- #997, #1077: Deprecate Bigarray.*.map_file and add Unix.map_file as a
  first step towards moving Bigarray to the stdlib
  (Jérémie Dimino and Xavier Leroy)

### Toplevel:

- #7060, #1035: Print exceptions in installed custom printers
  (Tadeu Zagallo, review by David Allsopp)

### Tools:

- #5163: ocamlobjinfo, dump globals defined by bytecode executables
  (Stéphane Glondu)

- #7333: ocamldoc, use the first sentence of text file as
  a short description in overviews.
  (Florian Angeletti)

- #848: ocamldoc, escape link targets in HTML output
  (Etienne Millon, review by Gabriel Scherer, Florian Angeletti and
  Daniel Bünzli)

- #986: ocamldoc, use relative paths in error message
  to solve ocamlbuild+doc usability issue (ocaml/ocamlbuild#79)
  (Gabriel Scherer, review by Florian Angeletti, discussion with Daniel Bünzli)

- #1017: ocamldoc, add an option to detect code fragments that could be
  transformed into a cross-reference to a known element.
  (Florian Angeletti, review and suggestion by David Allsopp)

- clarify ocamldoc text parsing error messages
  (Gabriel Scherer)

### Compiler distribution build system:

- #7377: remove -std=gnu99 for newer gcc versions
  (Damien Doligez, report by ygrek)

- #7452, #1228: tweak GCC options to try to avoid the
  Skylake/Kaby lake bug
  (Damien Doligez, review by David Allsopp, Xavier Leroy and Mark Shinwell)

- #693: fail on unexpected errors or warnings within caml_example
  environment.
  (Florian Angeletti)

- #803: new ocamllex-based tool to extract bytecode compiler
  opcode information from C headers.
  (Nicolás Ojeda Bär)

- #827: install missing mli and cmti files, new make target
  install-compiler-sources for installation of compiler-libs ml files
  (Hendrik Tews)

- #887: allow -with-frame-pointers if clang is used as compiler on Linux
  (Bernhard Schommer)

- #898: fix locale-dependence of primitive list order,
  detected through reproducible-builds.org.
  (Hannes Mehnert, review by Gabriel Scherer and Ximin Luo)

- #907: Remove unused variable from the build system
  (Sébastien Hinderer, review by whitequark, Gabriel Scherer, Adrien Nader)

- #911: Clarify the use of C compiler related variables in the build system.
  (Sébastien Hinderer, review by Adrien Nader, Alain Frisch, David Allsopp)

- #919: use clang as preprocessor assembler if clang is used as compiler
  (Bernhard Schommer)

- #927: improve the detection of hashbang support in the configure script
  (Armaël Guéneau)

- #932: install ocaml{c,lex}->ocaml{c,lex}.byte symlink correctly
  when the opt target is built but opt.opt target is not.
  (whitequark, review by Gabriel Scherer)

- #935: allow build in Android's termux
  (ygrek, review by Gabriel Scherer)

- #984: Fix compilation of compiler distribution when Spacetime
  enabled
  (Mark Shinwell)

- #991: On Windows, fix installation when native compiler is not
  built
  (Sébastien Hinderer, review by David Allsopp)

- #1033: merge Unix and Windows build systems in the root directory
  (Sébastien Hinderer, review by Damien Doligez and Adrien Nader)

- #1047: Make .depend files generated for C sources more portable
  (Sébastien Hinderer, review by Xavier Leroy and David Allsopp)

- #1076: Simplify ocamlyacc's build system
  (Sébastien Hinderer, review by David Allsopp)

### Compiler distribution build system: Makefile factorization

The compiler distribution build system (the set of Makefiles used to
build the compiler distribution) traditionally had separate Makefiles
for Unix and Windows, which lead to some amount of duplication and
subtle differences and technical debt in general -- for people working
on the compiler distribution, but also cross-compilation or porting to
new systems. During the 4.05 development period, Sébastien Hinderer
worked on harmonizing the build rules and merging the two build
systems.

* Some changes were made to the config/Makefile file which
  is exported as $(ocamlc -where)/Makefile.config, and on
  which some advanced users might rely. The changes are
  as follows:
  - a BYTERUN variable was added that points to the installed ocamlrun
  - the PARTIALLD variable was removed (PACKLD is more complete)
  - the always-empty DLLCCCOMPOPTS was removed
  - the SHARED variable was removed; its value is "shared" or "noshared",
    which duplicates the existing and more convenient
    SUPPORTS_SHARED_LIBRARIES variable whose value is "true" or "false".

  Note that Makefile.config may change further in the future and relying
  on it is a bit fragile. We plan to make `ocamlc -config` easier to use
  for scripting purposes, and have a stable interface there. If you rely
  on Makefile.config, you may want to get in touch with Sébastien Hinderer
  or participate to #7116 (Allow easy retrieval of Makefile.config's values)
  or #7172 (More information in ocamlc -config).

The complete list of changes is listed below.

- #705: update Makefile.nt so that ocamlnat compiles
  for non-Cygwin Windows ports.
  (Sébastien Hinderer, review by Alain Frisch)

- #729: Make sure ocamlnat is built with a $(EXE) extension, merge
  rules between Unix and Windows Makefiles
  (Sébastien Hinderer, review by Alain Frisch)

- #762: Merge build systems in the yacc/ directory.
  (Sébastien Hinderer, review by David Allsopp, Alain Frisch)

- #764: Merge build systems in the debugger/ directory.
  (Sébastien Hinderer, review by Alain Frisch)

- #785: Merge build systems in otherlibs/systhreads/
  (Sébastien Hinderer, review by Alain Frisch, David Allsopp,
   testing and regression fix by Jérémie Dimino)

- #788: Merge build systems in subdirectories of otherlibs/.
  (Sébastien Hinderer, review by Alain Frisch)

- #808, #906: Merge Unix and Windows build systems
  in the ocamldoc/ directory
  (Sébastien Hinderer, review by Alain Frisch)

- #812: Merge build systems in the tools/ subdirectory
  (Sébastien Hinderer, review by Alain Frisch)

- #866: Merge build systems in the stdlib/ directory
  (Sébastien Hinderer, review by David Allsopp and Adrien Nader)

- #941: Merge Unix and Windows build systems in the asmrun/ directory
  (Sébastien Hinderer, review by Mark Shinwell, Adrien Nader,
   Xavier Leroy, David Allsopp, Damien Doligez)

- #981: Merge build systems in the byterun/ directory
  (Sébastien Hinderer, review by Adrien Nader)

- #1033, #1048: Merge build systems in the root directory
  (Sébastien Hinderer, review by Adrien Nader and Damien Doligez,
   testing and regression fix by Andreas Hauptmann)

### Internal/compiler-libs changes:

- #673: distinguish initialization of block fields from mutation in lambda.
  (Frédéric Bour, review by Xavier Leroy, Stephen Dolan and Mark Shinwell)

- #744, #781: fix duplicate self-reference in imported cmi_crcs
  list in .cmti files + avoid rebuilding cmi_info record when creating
  .cmti files
  (Alain Frisch, report by Daniel Bünzli, review by Jérémie Dimino)

- #881: change `Outcometree.out_variant` to be more general.
  `Ovar_name of out_ident * out_type list` becomes `Ovar_type of out_type`.
  (Valentin Gatien-Baron, review by Leo White)

- #908: refactor PIC-handling in the s390x backend
  (Gabriel Scherer, review by Xavier Leroy and Mark Shinwell)

### Bug fixes:

- #5115: protect all byterun/fail.c functions against
  uninitialized caml_global_data (only changes the bytecode behavior)
  (Gabriel Scherer, review by Xavier Leroy)

- #6136, #967: Fix Closure so that overapplication evaluation order
  matches the bytecode compiler and Flambda.
  (Mark Shinwell, report by Jeremy Yallop, review by Frédéric Bour)

- #6550, #1094: Allow creation of empty .cmxa files on macOS
  (Mark Shinwell)

- #6594, #955: Remove "Istore_symbol" specific operation on x86-64.
  This is more robust and in particular avoids assembly failures on Win64.
  (Mark Shinwell, review by Xavier Leroy, testing by David Allsopp and
   Olivier Andrieu)

- #6903: Unix.execvpe doesn't change environment on Cygwin
  (Xavier Leroy, report by Adrien Nader)

- #6987: Strange error message probably caused by
  universal variable escape (with polymorphic variants)
  (Jacques Garrigue, report by Mikhail Mandrykin and Leo White)

- #7216, #949: don't require double parens in Functor((val x))
  (Jacques Garrigue, review by Valentin Gatien-Baron)

- #7331: ocamldoc, avoid infinite loop in presence of self alias,
  i.e. module rec M:sig end = M
  (Florian Angeletti, review Gabriel Scherer)

- #7346, #966: Fix evaluation order problem whereby expressions could
  be incorrectly re-ordered when compiling with Flambda.  This also fixes one
  example of evaluation order in the native code compiler not matching the
  bytecode compiler (even when not using Flambda)
  (Mark Shinwell, Leo White, code review by Pierre Chambart)

- #7348: Private row variables can escape their scope
  (Jacques Garrigue, report by Leo White)

- #7407: Two not-quite-standard C idioms rejected by SUNWSPro compilers
  (Xavier Leroy)

- #7421: Soundness bug with GADTs and lazy
  (Jacques Garrigue, report by Leo White)

- #7424: Typechecker diverges on unboxed type declaration
  (Jacques Garrigue, report by Stephen Dolan)

- #7426, #965: Fix fatal error during object compilation (also
  introduces new [Pfield_computed] and [Psetfield_computed] primitives)
  (Mark Shinwell, report by Ulrich Singer)

- #7427, #959: Don't delete let bodies in Cmmgen
  (Mark Shinwell, report by Valentin Gatien-Baron)

- #7432: Linking modules compiled with -labels and -nolabels is not safe
  (Jacques Garrigue, report by Jeremy Yallop)

- #7437: typing assert failure with nonrec priv
  (Jacques Garrigue, report by Anil Madhavapeddy)

- #7438: warning +34 exposes #row with private types
  (Alain Frisch, report by Anil Madhavapeddy)

- #7443, #990: spurious unused open warning with local open in patterns
  (Florian Angeletti, report by Gabriel Scherer)

- #7456, #1092: fix slow compilation on source files containing a lot
  of similar debugging information location entries
  (Mark Shinwell)

- #7504: fix warning 8 with unconstrained records
  (Florian Angeletti, report by John Whitington)

- #7511, #1133: Unboxed type with unboxed argument should not be accepted
  (Damien Doligez, review by Jeremy Yallop and Leo White)

- #805, #815, #833: check for integer overflow in String.concat
  (Jeremy Yallop,
   review by Damien Doligez, Alain Frisch, Daniel Bünzli, Fabrice Le Fessant)

- #881: short-paths did not apply to some polymorphic variants
  (Valentin Gatien-Baron, review by Leo White)

- #886: Fix Ctype.moregeneral's handling of row_name
  (Leo White, review by Jacques Garrigue)

- #934: check for integer overflow in Bytes.extend
  (Jeremy Yallop, review by Gabriel Scherer)

- #956: Keep possibly-effectful expressions when optimizing multiplication
  by zero.
  (Jeremy Yallop, review by Nicolás Ojeda Bär, Xavier Leroy and Mark Shinwell)

- #977: Catch Out_of_range in ocamldebug's "list" command
  (Yunxing Dai)

- #983: Avoid removing effectful expressions in Closure, and
  eliminate more non-effectful ones
  (Alain Frisch, review by Mark Shinwell and Gabriel Scherer)

- #987: alloc_sockaddr: don't assume a null terminator. It is not inserted
  on macOS by system calls that fill in a struct sockaddr (e.g. getsockname).
  (Anton Bachin)

- #998: Do not delete unused closures in un_anf.ml.
  (Leo White, review by Mark Shinwell and Pierre Chambart)

- #1019: Fix fatal error in Flambda mode "[functions] does not map set of
  closures ID"
  (Pierre Chambart, code review by Mark Shinwell and Leo White)

- #1075: Ensure that zero-sized float arrays have zero tags.
  (Mark Shinwell, Leo White, review by Xavier Leroy)

* #1088: Gc.minor_words now returns accurate numbers.
  (compatibility: the .mli declaration of `Gc.minor_words`
   and `Gc.get_minor_free` changed, which may break libraries
   re-exporting these values.)
  (Stephen Dolan, review by Pierre Chambart and Xavier Leroy)

OCaml 4.04.2 (23 Jun 2017):
---------------------------

### Security fix:

- #7557: Local privilege escalation issue with ocaml binaries.
  (Damien Doligez, report by Eric Milliken, review by Xavier Leroy)

OCaml 4.04.1 (14 Apr 2017):
---------------------------

### Standard library:

- #7403, #894: fix a bug in Set.map as introduced in 4.04.0
  (Gabriel Scherer, report by Thomas Leonard)

### Tools:

- #7411: ocamldoc, avoid nested <pre> tags in module description.
  (Florian Angeletti, report by user 'kosik')

- #7488: ocamldoc, wrong Latex output for variant types
  with constructors without arguments.
  (Florian Angeletti, report by Xavier Leroy)

### Build system:

- #7373, #1023: New flexlink target in Makefile.nt to bootstrap the
  flexlink binary only, rather than the flexlink binary and the FlexDLL C
  objects.
  (David Allsopp)

### Bug fixes:

- #7369: Str.regexp raises "Invalid_argument: index out of bounds"
  (Damien Doligez, report by John Whitington)

- #7373, #1023: Fix ocamlmklib with bootstrapped FlexDLL. Bootstrapped
  FlexDLL objects are now installed to a subdirectory flexdll of the Standard
  Library which allows the compilers to pick them up explicitly and also
  ocamlmklib to include them without unnecessarily adding the entire Standard
  Library.
  (David Allsopp)

- #7385, #1057: fix incorrect timestamps returned by Unix.stat on Windows
  when either TZ is set or system date is in DST.
  (David Allsopp, report and initial fix by Nicolás Ojeda Bär, review and
   superior implementation suggestion by Xavier Leroy)

- #7405, #903: s390x: Fix address of caml_raise_exn in native dynlink
  modules.
  (Richard Jones, review by Xavier Leroy)

- #7417, #930: ensure 16 byte stack alignment inside caml_allocN on x86-64
  for ocaml build with WITH_FRAME_POINTERS defined
  (Christoph Cullmann)

- #7456, #1092: fix slow compilation on source files containing a lot
  of similar debugging information location entries
  (Mark Shinwell)

- #7457: a case of double free in the systhreads library (POSIX
  implementation).
  (Xavier Leroy, report by Chet Murthy)

- #7460, #1011: catch uncaught exception when unknown files are passed
  as argument (regression in 4.04.0)
  (Bernhard Schommer, review by Florian Angeletti and Gabriel Scherer,
   report by Stephen Dolan)

- #7505: Memory cannot be released after calling
    Bigarray.Genarray.change_layout.
  (Damien Doligez and Xavier Leroy, report by Liang Wang)

- #912: Fix segfault in Unix.create_process on Windows caused by wrong header
  configuration.
  (David Allsopp)

- #980: add dynlink options to ocamlbytecomp.cmxa to allow ocamlopt.opt
  to load plugins. See http://github.com/OCamlPro/ocamlc-plugins for examples.
  (Fabrice Le Fessant, review by David Allsopp)

- #992: caml-types.el: Fix missing format argument, so that it can show kind
  of call at point correctly.
  (Chunhui He)

- #1043: Allow Windows CRLF line-endings in ocamlyacc on Unix and Cygwin.
  (David Allsopp, review by Damien Doligez and Xavier Leroy)

- #1072: Fix segfault in Sys.runtime_parameters when exception backtraces
  are enabled.
  (Olivier Andrieu)

OCaml 4.04.0 (4 Nov 2016):
--------------------------

(Changes that can break existing programs are marked with a "*")

### Language features:

- #7233: Support GADT equations on non-local abstract types
  (Jacques Garrigue)

- #187, #578: Local opening of modules in a pattern.
  Syntax: "M.(p)", "M.[p]","M.[| p |]", "M.{p}"
  (Florian Angeletti, Jacques Garrigue, review by Alain Frisch)

- #301: local exception declarations "let exception ... in"
  (Alain Frisch)

- #508: Allow shortcut for extension on semicolons: ;%foo
  (Jérémie Dimino)

- #606: optimized representation for immutable records with a single
  field, and concrete types with a single constructor with a single argument.
  This is triggered with a [@@unboxed] attribute on the type definition.
  Currently mutually recursive datatypes are not well supported, this
  limitation should be lifted in the future (see #7364).
  (Damien Doligez)

### Compiler user-interface and warnings:

* #6475, #464: interpret all command-line options before compiling any
  files, changes (improves) the semantics of repeated -o options or -o
  combined with -c see the super-detailed commit message at
  https://github.com/ocaml/ocaml/commit/da56cf6dfdc13c09905c2e07f1d4849c8346eec8
  (whitequark)

- #7139: clarify the wording of Warning 38
  (Unused exception or extension constructor)
  (Gabriel Scherer)

* #7147, #475: add colors when reporting errors generated by ppx rewriters.
  Remove the `Location.errorf_prefixed` function which is no longer relevant
  (Simon Cruanes, Jérémie Dimino)

- #7169, #501: clarify the wording of Warning 8
  (Non-exhaustivity warning for pattern matching)
  (Florian Angeletti, review and report by Gabriel Scherer)

* #591: Improve support for OCAMLPARAM: (i) do not use objects
  files with -a, -pack, -shared; (ii) use "before" objects in the toplevel
  (but not "after" objects); (iii) use -I dirs in the toplevel,
  (iv) fix bug where -I dirs were ignored when using threads
  (Marc Lasson, review by Damien Doligez and Alain Frisch)

- #648: New -plugin option for ocamlc and ocamlopt, to dynamically extend
  the compilers at runtime.
  (Fabrice Le Fessant)

- #684: Detect unused module declarations
  (Alain Frisch)

- #706: Add a settable Env.Persistent_signature.load function so
  that cmi files can be loaded from other sources. This can be used to
  create self-contained toplevels.
  (Jérémie Dimino)

### Standard library:

- #6279, #553: implement Set.map
  (Gabriel Scherer)

- #6820, #560: Add Obj.reachable_words to compute the
  "transitive" heap size of a value
  (Alain Frisch, review by Mark Shinwell and Damien Doligez)

- #473: Provide `Sys.backend_type` so that user can write backend-specific
  code in some cases (for example,  code generator).
  (Hongbo Zhang)

- #589: Add a non-allocating function to recover the number of
  allocated minor words.
  (Pierre Chambart, review by Damien Doligez and Gabriel Scherer)

- #626: String.split_on_char
  (Alain Frisch)

- #669: Filename.extension and Filename.remove_extension
  (Alain Frisch, request by Edgar Aroutiounian, review by Daniel Bünzli
  and Damien Doligez)

- #674: support unknown Sys.os_type in Filename, defaulting to Unix
  (Filename would previously fail at initialization time for
   Sys.os_type values other than "Unix", "Win32" and "Cygwin";
   mirage-os uses "xen")
  (Anil Madhavapeddy)

- #772 %string_safe_set and %string_unsafe_set are deprecated aliases
  for %bytes_safe_set and %bytes_unsafe_set.
  (Hongbo Zhang and Damien Doligez)

### Other libraries

- #4834, #592: Add a Biggarray.Genarray.change_layout function
  to switch bigarrays between C and fortran layouts.
  (Guillaume Hennequin, review by Florian Angeletti)

### Code generation and optimizations:

- #4747, #328: Optimize Hashtbl by using in-place updates of its
  internal bucket lists.  All operations run in constant stack size
  and are usually faster, except Hashtbl.copy which can be much
  slower
  (Alain Frisch)

- #6217, #538: Optimize performance of record update:
  no more performance cliff when { foo with t1 = ..; t2 = ...; ... }
  hits 6 updated fields
  (Olivier Nicole, review by Thomas Braibant and Pierre Chambart)

- #7023, #336: Better unboxing strategy
  (Alain Frisch, Pierre Chambart)

- #7244, #840: Ocamlopt + flambda requires a lot of memory
  to compile large array literal expressions
  (Pierre Chambart, review by Mark Shinwell)

- #7291, #780: Handle specialisation of recursive function that does
  not always preserve the arguments
  (Pierre Chambart, Mark Shinwell, report by Simon Cruanes)

- #7328, #702: Do not eliminate boxed int divisions by zero and
  avoid checking twice if divisor is zero with flambda.
  (Pierre Chambart, report by Jeremy Yallop)

- #427: Obj.is_block is now an inlined OCaml function instead of a
  C external.  This should be faster.
  (Demi Marie Obenour)

- #580: Optimize immutable float records
  (Pierre Chambart, review by Mark Shinwell)

- #602: Do not generate dummy code to force module linking
  (Pierre Chambart, reviewed by Jacques Garrigue)

- #703: Optimize some constant string operations when the "-safe-string"
  configure time option is enabled.
  (Pierre Chambart)

- #707: Load cross module information during a meet
  (Pierre Chambart, report by Leo White, review by Mark Shinwell)

- #709: Share a few more equal switch branches
  (Pierre Chambart, review by Gabriel Scherer)

- #712: Small improvements to type-based optimizations for array
  and lazy
  (Alain Frisch, review by Pierre Chambart)

- #714: Prevent warning 59 from triggering on Lazy of constants
  (Pierre Chambart, review by Leo White)

- #723 Sort emitted functions according to source location
  (Pierre Chambart, review by Mark Shinwell)

- Lack of type normalization lead to missing simple compilation for "lazy x"
  (Alain Frisch)

### Runtime system:

- #7203, #534: Add a new primitive caml_alloc_float_array to allocate an
  array of floats
  (Thomas Braibant)

- #7210, #562: Allows to register finalisation function that are
  called only when a value will never be reachable anymore. The
  drawbacks compared to the existing one is that the finalisation
  function is not called with the value as argument. These finalisers
  are registered with `GC.finalise_last`
  (François Bobot reviewed by Damien Doligez and Leo White)

- #247: In previous OCaml versions, inlining caused stack frames to
  disappear from stacktraces. This made debugging harder in presence of
  optimizations, and flambda was going to make this worse. The debugging
  information produced by the compiler now enables the reconstruction of the
  original backtrace. Use `Printexc.get_raw_backtrace_next_slot` to traverse
  the list of inlined stack frames.
  (Frédéric Bour, review by Mark Shinwell and Xavier Leroy)

- #590: Do not perform compaction if the real overhead is less than expected
  (Thomas Braibant)

### Tools:

- #7189: toplevel #show, follow chains of module aliases
  (Gabriel Scherer, report by Daniel Bünzli, review by Thomas Refis)

- #7248: have ocamldep interpret -open arguments in left-to-right order
  (Gabriel Scherer, report by Anton Bachin)

- #7272, #798: ocamldoc, missing line breaks in type_*.html files
  (Florian Angeletti)

- #7290: ocamldoc, improved support for inline records
  (Florian Angeletti)

- #7323, #750: ensure "ocamllex -ml" works with -safe-string
  (Hongbo Zhang)

- #7350, #806: ocamldoc, add viewport metadata to generated html pages
  (Florian Angeletti, request by Daniel Bünzli)

- #452: Make the output of ocamldep more stable
  (Alain Frisch)

- #548: empty documentation comments
  (Florian Angeletti)

- #575: Add the -no-version option to the toplevel
  (Sébastien Hinderer)

- #598: Add a --strict option to ocamlyacc treat conflicts as errors
  (this option is now used for the compiler's parser)
  (Jeremy Yallop)

- #613: make ocamldoc use -open arguments
  (Florian Angeletti)

- #718: ocamldoc, fix order of extensible variant constructors
  (Florian Angeletti)

### Debugging and profiling:

- #585: Spacetime, a new memory profiler (Mark Shinwell, Leo White)

### Manual and documentation:

- #7007, #7311: document the existence of OCAMLPARAM and
  ocaml_compiler_internal_params
  (Damien Doligez, reports by Wim Lewis and Gabriel Scherer)

- #7243: warn users against using WinZip to unpack the source archive
  (Damien Doligez, report by Shayne Fletcher)

- #7245, #565: clarification to the wording and documentation
  of Warning 52 (fragile constant pattern)
  (Gabriel Scherer, William, Adrien Nader, Jacques Garrigue)

- #PR7265, #769: Restore 4.02.3 behaviour of Unix.fstat, if the
  file descriptor doesn't wrap a regular file (win32unix only)
  (Andreas Hauptmann, review by David Allsopp)

- #7288: flatten : Avoid confusion
  (Damien Doligez, report by user 'tormen')

- #7355: Gc.finalise and lazy values
  (Jeremy Yallop)

- #842: Document that [Store_field] must not be used to populate
  arrays of values declared using [CAMLlocalN] (Mark Shinwell)

### Compiler distribution build system:

- #324: Compiler developers: Adding new C primitives to the
  standard runtime doesn't require anymore to run `make bootstrap`
  (François Bobot)

- #384: Fix compilation using old Microsoft C Compilers not
  supporting secure CRT functions (SDK Visual Studio 2005 compiler and
  earlier) and standard 64-bit integer literals (Visual Studio .NET
  2002 and earlier)
  (David Allsopp)

- #507: More sharing between Unix and Windows makefiles
  (whitequark, review by Alain Frisch)

* #512, #587: Installed `ocamlc`, `ocamlopt`, and `ocamllex` are
  now the native-code versions of the tools, if those versions were
  built.
  (Demi Marie Obenour)

- #525: fix build on OpenIndiana
  (Sergey Avseyev, review by Damien Doligez)

- #687: "./configure -safe-string" to get a system where
  "-unsafe-string" is not allowed, thus giving stronger non-local
  guarantees about immutability of strings
  (Alain Frisch, review by Hezekiah M. Carty)

### Bug fixes:

* #6505: Missed Type-error leads to a segfault upon record access.
  (Jacques Garrigue, extra report by Stephen Dolan)
  Proper fix required a more restrictive approach to recursive types:
  mutually recursive types are seen as abstract types (i.e. non-contractive)
  when checking the well-foundedness of the recursion.

* #6752: Nominal types and scope escaping.
  Revert to strict scope for non-generalizable type variables, cf. Mantis.
  Note that this is actually stricter than the behavior before 4.03,
  cf. #7313, meaning that you may sometimes need to add type annotations
  to explicitly instantiate non-generalizable type variables.
  (Jacques Garrigue, following discussion with Jeremy Yallop,
   Nicolás Ojeda Bär and Alain Frisch)

- #7112: Aliased arguments ignored for equality of module types
  (Jacques Garrigue, report by Leo White)

- #7134: compiler forcing aliases it shouldn't while reporting type errors
  (Jacques Garrigue, report and suggestion by sliquister)

- #7153: document that Unix.SOCK_SEQPACKET is not really usable.

- #7165, #494: uncaught exception on invalid lexer directive
  (Gabriel Scherer, report by KC Sivaramakrishnan using afl-fuzz)

- #7257, #583: revert a 4.03 change of behavior on (Unix.sleep 0.),
  it now calls (nano)sleep for 0 seconds as in (< 4.03) versions.
  (Hannes Mehnert, review by Damien Doligez)

- #7259 and #603: flambda does not collapse pattern matching
  in some cases
  (Pierre Chambart, report by Reed Wilson, review by Mark Shinwell)

- #7260: GADT + subtyping compile time crash
  (Jacques Garrigue, report by Nicolás Ojeda Bär)

- #7269: Segfault from conjunctive constraints in GADT
  (Jacques Garrigue, report by Stephen Dolan)

- #7276: Support more than FD_SETSIZE sockets in Windows' emulation
  of select
  (David Scott, review by Alain Frisch)

* #7278: Prevent private inline records from being mutated
  (Alain Frisch, report by Pierre Chambart)

- #7284: Bug in mcomp_fields leads to segfault
  (Jacques Garrigue, report by Leo White)

- #7285: Relaxed value restriction broken with principal
  (Jacques Garrigue, report by Leo White)

- #7297: -strict-sequence turns off Warning 21
  (Jacques Garrigue, report by Valentin Gatien-Baron)

- #7299: remove access to OCaml heap inside blocking section in win32unix
  (David Allsopp, report by Andreas Hauptmann)

- #7300: remove access to OCaml heap inside blocking in Unix.sleep on Windows
  (David Allsopp)

- #7305: -principal causes loop in type checker when compiling
  (Jacques Garrigue, report by Anil Madhavapeddy, analysis by Leo White)

- #7330: Missing exhaustivity check for extensible variant
  (Jacques Garrigue, report by Elarnon *)

- #7374: Contractiveness check unsound with constraints
  (Jacques Garrigue, report by Leo White)

- #7378: GADT constructors can be re-exposed with an incompatible type
  (Jacques Garrigue, report by Alain Frisch)

- #7389: Unsoundness in GADT exhaustiveness with existential variables
  (Jacques Garrigue, report by Stephen Dolan)

* #533: Thread library: fixed [Thread.wait_signal] so that it
  converts back the signal number returned by [sigwait] to an
  OS-independent number
  (Jérémie Dimino)

- #600: (similar to #555) ensure that register typing constraints are
  respected at N-way join points in the control flow graph
  (Mark Shinwell)

- #672: Fix float_of_hex parser to correctly reject some invalid forms
  (Bogdan Tătăroiu, review by Thomas Braibant and Alain Frisch)

- #700: Fix maximum weak bucket size
  (Nicolás Ojeda Bär, review by François Bobot)

- #708 Allow more module aliases in strengthening (Leo White)

- #713, #7301: Fix wrong code generation involving lazy values in Flambda
  mode
  (Mark Shinwell, review by Pierre Chambart and Alain Frisch)

- #721: Fix infinite loop in flambda due to [@@specialise] annotations

- #779: Building native runtime on Windows could fail when bootstrapping
  FlexDLL if there was also a system-installed flexlink
  (David Allsopp, report Michael Soegtrop)

- #805, #815, #833: check for integer overflow in String.concat
  (Jeremy Yallop,
   review by Damien Doligez, Alain Frisch, Daniel Bünzli, Fabrice Le Fessant)

- #810: check for integer overflow in Array.concat
  (Jeremy Yallop)

- #814: fix the Buffer.add_substring bounds check to handle overflow
  (Jeremy Yallop)

- #880: Fix [@@inline] with default parameters in flambda (Leo White)

* #1353: add labels to BytesLabels.sub_string (Jacques Garrigue)

### Internal/compiler-libs changes:

- #7200, #539: Improve, fix, and add test for parsing/pprintast.ml
  (Runhang Li, David Sheets, Alain Frisch)

- #351: make driver/pparse.ml functions type-safe
  (Gabriel Scherer, Dmitrii Kosarev, review by Jérémie Dimino)

- #516: Improve Texp_record constructor representation, and
  propagate updated record type information
  (Pierre Chambart, review by Alain Frisch)

- #678: Graphics.close_graph crashes 64-bit Windows ports (re-implementation
  of #3963)
  (David Allsopp)

- #679: delay registration of docstring after the mapper is applied
  (Hugo Heuzard, review by Leo White)

- #872: don't attach (**/**) comments to any particular node
  (Thomas Refis, review by Leo White)

OCaml 4.03.0 (25 Apr 2016):
---------------------------

(Changes that can break existing programs are marked with a "*")

### Language features:

- #5528: inline records for constructor arguments
  (Alain Frisch)

- #6220, #6403, #6437, #6801:
  Improved redundancy and exhaustiveness checks for GADTs.
  Namely, the redundancy checker now checks whether the uncovered pattern
  of the pattern is actually inhabited, exploding at most one wild card.
  This is also done for exhaustiveness when there is only one case.
  Additionally, one can now write unreachable cases, of the form
  "pat -> .", which are treated by the redundancy check.
  (Jacques Garrigue)

- #6374: allow "_ t" as a short-hand for "(_, _, ..) t" for n-ary type
  constructors
  (Alain Frisch)

- #6714: allow [@@ocaml.warning] on most structure and signature items:
  values, modules, module types
  (whitequark)

- #6806: Syntax shortcut for putting a type annotation on a record field:
  { f1 : typ = e } is sugar for { f1 = (e : typ) }
  { f1 : typ } is sugar for { f1 = (f1 : typ) }
  (Valentin Gatien-Baron, review by Jérémie Dimino)

- #6806: Allow type annotations before the "->" in "fun <args> -> <expr>"
  fun x y : (int * int) -> (x, y)
  (Valentin Gatien-Baron, review by Jérémie Dimino)

- #26: support for "(type a b)" as syntactic sugar for "(type a) (type b)"
  (Gabriel Scherer)

- #42: short functor type syntax: "S -> T" for "functor (_ : S) -> T"
  (Leo White)

- #88: allow field punning in object copying expressions:
  {< x; y; >} is sugar for {< x = x; y = y; >}
  (Jeremy Yallop)

- #112: octal escape sequences for char and string literals
  "Make it \o033[1mBOLD\o033[0m"
  (Rafaël Bocquet, request by John Whitington)

- #167: allow to annotate externals' arguments and result types so
  they can be unboxed or untagged: [@unboxed], [@untagged]. Supports
  untagging int and unboxing int32, int64, nativeint and float.
  (Jérémie Dimino, Mark Shinwell)

- #173: [@inline] and [@inlined] attributes (for function declarations
  and call sites respectively) to control inlining
  (Pierre Chambart, Mark Shinwell)

- #188: accept [@@immediate] attribute on type declarations to mark types
  that are represented at runtime by an integer
  (Will Crichton, reviewed by Leo White)

* #234: allow "[]" as a user-defined constructor. Demand parenthesis
  around "::" when using "::" as user-defined constructor:
  code using "| :: of ..." must change to "| (::) of ...".
  (Runhang Li, review by Damien Doligez)

- #240: replace special annotations on externals by attributes:
  * "float" is generalized to [@@unboxed]
  * "noalloc" becomes [@@noalloc]
  Deprecate "float" and "noalloc".
  (Jérémie Dimino)

- #254: @ocaml.warn_on_literal_pattern attribute on constructors to
  warn when the argument is matches against a constant pattern.  This
  attribute is applied on predefined exception constructors which
  carry purely informational (with no stability guarantee) messages.
  (Alain Frisch)

- #268: hexadecimal notation for floating-point literals: -0x1.ffffp+987
  In OCaml source code, FP literals can be written using the hexadecimal
  notation 0x<mantissa in hex>p<exponent> from ISO C99.
  (Xavier Leroy)

- #273: allow to get the extension slot of an extension constructor
  by writing [%extension_constructor <path>]
  (Jérémie Dimino)

- #282: change short-paths penalty heuristic to assign the same cost to
  idents containing double underscores as to idents starting with an underscore
  (Thomas Refis, Leo White)

- #6681 #326: signature items are now accepted as payloads for
  extension and attributes, using the syntax [%foo: SIG ] or [@foo: SIG ].
  Examples: "[%%client: val foo : int]" or "val%client foo : int".
  (Alain Frisch and Gabriel Radanne)

* #342: Allow shortcuts for extension and attributes on all keywords:
  module%foo, class[@foo], etc.
  The attribute in "let[@foo] .. in .." is now attached to the value binding,
  not to the expression.
  (Gabriel Radanne)

### Compilers:

* #4231, #5461: warning 31 is now fatal by default
  (Warning 31: A module is linked twice in the same executable.)
  This is an interim solution; double-linking of modules has dangerous
  semantics, eg. exception constructors end up with two distinct declarations.
  (Alain Frisch)

- #4800: better compilation of tuple assignment
  (Gabriel Scherer and Alain Frisch)

- #5995: keep -for-pack into account to name exceptions;
  -for-pack should now be used during bytecode compilation as well
  (Alain Frisch, report by Christophe Troestler)

- #6400: better error message for '_' used as an expression
  (Alain Frisch, report by whitequark)

- #6501: harden the native-code generator against certain uses of "%identity"
  (Xavier Leroy, report by Antoine Miné)

- #6636: add --version option
  (whitequark)

- #6679: fix pprintast printing of constraints in type declarations
  (Alain Frisch, report by Jun Furuse)

- #6737: fix Typedtree attributes on (fun x -> body) expressions
  (Alain Frisch, report by Oleg Kiselyov)

* #6865: remove special case for parsing "let _ = expr" in structures
  (Jérémie Dimino, Alain Frisch)

* #6438, #7059, #315: Pattern guard disables exhaustiveness check
  (function Some x when x = 0 -> ()) will now raise warning 8 (non-exhaustive)
  instead of warning 25 (all clauses are guarded). 25 isn't raised anymore.
  Projects that set warning 8 as an error may fail to compile (presumably
  this is the semantics they wanted).
  (Alain Frisch, request by Martin Jambon and John Whitington)

- #6920: fix debug information around uses of %apply or %revapply
  (Jérémie Dimino, report by Daniel Bünzli)

- #6939: Segfault with improper use of let-rec
  (Alain Frisch)

- #6943: native-code generator for POWER/PowerPC 64 bits, both in
  big-endian (ppc64) and little-endian (ppc64le) configuration,
  inspired from RedHat's unofficial ppc64 and ppc64le ports
  (Xavier Leroy)

- #6979: better code generation in x86-32 backend for copying floats to
  the stack
  (Marc Lasson, review by Xavier Leroy)

- #7018: fix missing identifier renaming during inlining
  (Alain Frisch, review by Xavier Leroy)

- #7022, #259: unbox float and boxed ints earlier, avoid second pass
  (Alain Frisch)

- #7026, #288: remove write barrier for polymorphic variants without
  arguments
  (Simon Cruanes)

- #7031: new warning 57, ambiguous guarded or-patterns
  (Luc Maranget, Gabriel Scherer, report by Martin Clochard and Claude Marché)

- #7064, #316: allowing to mark compilation units and sub-modules as
  deprecated
  (Alain Frisch)

- #7067: fix performance regression (wrt. 4.01) in the native compiler
  for long nested structures
  (Alain Frisch, report by Daniel Bünzli, review by Jacques Garrigue)

- #7097: fix strange syntax error message around illegal packaged module
  signature constraints
  (Alain Frisch, report by Jun Furuse)

- #7118, #7120, #408, #476: Bug fixed in stack unwinding
  metadata generation. Was a cause of crashes in GUI programs on OS X.
  (Bart Jacobs, review by Mark Shinwell)

- #7168: Exceeding stack limit in bytecode can lead to a crash.
  (Jacques-Henri Jourdan)

- #7232: Strange Pprintast output with ppx_deriving
  (Damien Doligez, report by Anton Bachin)

- #17: some cmm optimizations of integer operations with constants
  (Stephen Dolan, review by Pierre Chambart)

- #89: improve type-specialization of unapplied primitives:
  unapplied annotations (compare : int -> _),
  type propagation (List.sort compare [1;2;3])
  and propagation from module signatures now lead to specialization
  (Frédéric Bour, review by Gabriel Scherer)

- #107: Prevent more unnecessary float boxing, especially in `if` and `match`
  (Vladimir Brankov, review by Alain Frisch)

- #109: new (lazy) unboxing strategy for float and int references
  (Vladimir Brankov, review by Alain Frisch)

- #115: More precise typing of values at the C-- and Mach level.
  (Xavier Leroy, review by Pierre Chambart)

- #132: Flambda: new intermediate language and "middle-end" optimizers
  (Pierre Chambart, Mark Shinwell, Leo White)

- #212, #7226, #542: emit column position in gas assembly `.loc`
  (Frédéric Bour, Anton Bachin)

- #207: Colors in compiler messages (warnings, errors)
  configure with -color {auto|always|never} or TERM=dumb
  (Simon Cruanes, review by Gabriel Scherer)

- #258: more precise information on PowerPC instruction sizes
  (Pierre Chambart, Xavier Leroy)

- #263: improve code generation for if-equivalents of (&&) and (||)
  (Pierre Chambart)

- #270: Make [transl_exception_constructor] generate [Immutable] blocks
  (Mark Shinwell)

- #271: Fix incorrect mutability flag when records are built using "with"
  (Mark Shinwell)

- #275: native-code generator for IBM z System running Linux.
  In memoriam Gene Amdahl, 1922-2015.
  (Bill O'Farrell, Tristan Amini, Xavier Leroy)

- #282: relax short-paths safety check in presence of module aliases, take
  penalty into account while building the printing map.
  (Thomas Refis, Leo White)

- #306: Instrument the compiler to debug performance regressions
  (Pierre Chambart)

- #319: add warning 58 for missing cmx files, and
  extend -opaque option to mli files: a missing .cmx does not warn
  if the corresponding .cmi is compiled -opaque.
  (Leo White)

- #388: OCAML_FLEXLINK environment variable allows overriding flexlink
  command (David Allsopp)

- #392: put all parsetree invariants in a new module Ast_invariants
  (Jérémie Dimino)

- #407: don't display the name of compiled .c files when calling the
  Microsoft C Compiler (same as the assembler).
  (David Allsopp)

- #431: permit constant float arrays to be eligible for pattern match
  branch merging
  (Pierre Chambart)

- #455: provide more debugging information to Js_of_ocaml
  (Jérôme Vouillon)

- #514, #554: Added several command-line flags to explicitly enable
  settings that are currently the default:
  `-alias-deps`, `-app-funct`, `-no-keep-docs`, `-no-keep-locs`,
  `-no-principal`, `-no-rectypes`, `-no-strict-formats`
  (Demi Marie Obenour)

- #545: use reraise to preserve backtrace on
  `match .. with exception e -> raise e`
  (Nicolás Ojeda Bär, review by Gabriel Scherer)

### Runtime system:

* #596: make string/bytes distinguishable in the underlying
  compiler implementation; caml_fill_string and caml_create_string are
  deprecated and will be removed in the future, please use
  caml_fill_bytes and caml_create_bytes for migration
  (Hongbo Zhang, review by Damien Doligez, Alain Frisch, and Hugo Heuzard)

- #3612, #2429: allow allocating custom block with finalizers
  in the minor heap.
  (Pierre Chambart)

* #6517: use ISO C99 types {,u}int{32,64}_t in preference to our homegrown
  types {,u}int{32,64}.
  C stubs may have to be updated as {,u}int{32,64}_t are not defined anymore.
  (Xavier Leroy)

- #6760: closures evaluated in the toplevel can now be marshalled
  (whitequark, review by Jacques-Henri Jourdan)

- #6902, #210: emit a runtime warning on stderr
  when finalizing an I/O channel which is still open:
    "channel opened on file '...' dies without being closed"
  this is controlled by OCAMLRUNPARAM=W=1 or with Sys.enable_runtime_warnings.
  The behavior of affected program is not changed,
  but they should still be fixed.
  (Alain Frisch, review by Damien Doligez)

- Signal handling: for read-and-clear, use GCC/Clang atomic builtins
  if available.
  (Xavier Leroy)

- #6910, #224: marshaling (output_value, input_value, et al)
  now support marshaled data bigger than 4 Gb.
  (Xavier Leroy)

* #22: The undocumented layout of weak arrays has been changed. Finalisation
  functions are now run before the erasure of the corresponding values.

* #226: select higher levels of optimization for GCC >= 3.4 and Clang
  when compiling the run-time system and C stub code.
  "-std=gnu99 -O2 -fno-strict-aliasing -fwrapv" is used by default.
  This also affects default flags for user stubs compiled with "ocamlc -c foo.c"
  and may uncover bugs in them.
  (Xavier Leroy)

- #262: Multiple GC roots per compilation unit
  (Pierre Chambart, Mark Shinwell, review by Damien Doligez)

* #297: Several changes to improve the worst-case GC pause time.
  Changes Gc.control and Gc.major_slice and adds functions to the Gc module.
  (Damien Doligez, with help from François Bobot, Thomas Braibant, Leo White)

- #325: Add v=0x400 flag to OCAMLRUNPARAM to display GC stats on exit
  (Louis Gesbert, review by Alain Frisch)

### Standard library:

- #7848, #230: Array.map2, Array.iter2
  (John Christopher McAlpine)

- #5197, #63: Arg: allow flags such as --flag=arg as well as --flag arg
  (Richard Jones)

- #6017, #7034, #267: More efficient ifprintf implementation
  (Jeremy Yallop, review by Gabriel Scherer)

- #6296: Some documentation on the floating-point representations
    recognized by Pervasives.float_of_string
  (Xavier Leroy)

- #6316: Scanf.scanf failure on %u formats when reading big integers
  (Xavier Leroy, Benoît Vaugon)

- #6321: guarantee that "hypot infinity nan = infinity"
  (for conformance with ISO C99)
  (Xavier Leroy)

- #6390, #36: expose Sys.{int_size,max_wosize} for js_of_ocaml portability
  (Hugo Heuzard)

- #6449: Add Map.union
  (Alain Frisch)

* #6494: Add 'equal' functions in modules
  Bytes, Char, Digest, Int32, Int64, Nativeint, and String
  Users defining their own modules with signature 'module type of Int32'
  have to extend their implementation.
  (Romain Calascibetta)

* #6524, #79: Filename: Optional ?perms argument to open_temp_file
  May break partial applications of the function (fix by passing ?perms:None)
  (Daniel Bünzli, review by Kate Deplaix)

* #6525, #80: Add Uchar module to the standard library
  May introduce module name conflicts with existing projects.
  (Daniel Bünzli, review by Yoriyuki Yamagata and Damien Doligez)

- #6577: improve performance of %L, %l, %n, %S, %C format specifiers
  (Alain Frisch)

- #6585: fix memory leak in win32unix/createprocess.c
  (Alain Frisch, report by user 'aha')

- #6645, #174: Guarantee that Set.add, Set.remove, Set.filter
  return the original set if no change is required
  (Alain Frisch, Mohamed Iguernlala)

- #6649, #222: accept (int_of_string "+3")
  (John Christopher McAlpine)

- #6694, #6695, #124: deprecate functions using ISO-8859-1 character set
  in Char, Bytes, String and provide alternatives *_acii using US-ASCII.
  Affected functions:
    {Char,String,Bytes}.{uppercase,lowercase},
    {String,Bytes}.{capitalize,uncaptialize}
  (whitequark, review by Damien Doligez)

- #22: Add the Ephemeron module that implements ephemerons and weak
  hash table
  (François Bobot, review by Damien Doligez, Daniel Bünzli,
  Alain Frisch, Pierre Chambart)

- #164: more efficient (branchless) implementation of Pervasives.compare
  specialized at type 'float'.
  (Vladimir Brankov)

- #175: Guarantee that Map.add, Map.remove, Map.filter
  return the original map if no change is required.
  (Mohamed Iguernlala)

- #201: generalize types of Printf.{ifprintf,ikfprintf}
  (Maxence Guesdon)

- #216: add the missing POSIX.1-2001 signals in Sys
  (Guillaume Bury)

- #239: remove type-unsafe code from Stream
  (Pierre Chambart, review by Gabriel Scherer and Jeremy Yallop)

- #250: Check for negative start element in Array.sub
  (Jeremy Yallop)

- #265: new implementation of Queue avoiding Obj.magic
  (Jérémie Dimino)

- #268, #303: '%h' and '%H' modifiers for printf and scanf to
  support floating-point numbers in hexadecimal notation
  (Xavier Leroy, Benoît Vaugon)

- #272: Switch classify_float to [@@unboxed]
  (Alain Frisch)

- Improve speed of classify_float by not going through fpclassify()
  (Alain Frisch, Xavier Leroy)

- #277: Switch the following externals to [@@unboxed]:
  * {Nativeint,Int32,Int64}.{of,to}_float
  * Int{32,64}.float_of_bits
  * Int{32,64}.bits_of_float
  (Jérémie Dimino)

- #281: Switch the following externals to [@@unboxed]:
  * Sys.time (and [@@noalloc])
  * Pervasives.ldexp (and [@@noalloc])
  * Pervasives.compare for float, nativeint, int32, int64.
  (François Bobot)

- #3622, #195: add function Stack.fold
  (Simon Cruanes)

- #329: Add exists, for_all,  mem and memq functions in Array
  (Bernhard Schommer)

- #337: Add [Hashtbl.filter_map_inplace]
  (Alain Frisch)

- #356: Add [Format.kasprintf]
  (Jérémie Dimino, Mark Shinwell)

### Type system:

- #5545: Type annotations on methods cannot control the choice of abbreviation
  (Jacques Garrigue)

* #6465: allow incremental weakening of module aliases.
  This is done by adding equations to submodules when expanding aliases.
  In theory this may be incompatible is some corner cases defining a module
  type through inference, but no breakage known on published code.
  (Jacques Garrigue)

- #6593: Functor application in tests/basic-modules fails after commit 15405
  (Jacques Garrigue)

### Toplevel and debugger:

- #6113: Add descriptions to directives, and display them via #help
  (Nick Giannarakis, Berke Durak, Francis Southern and Gabriel Scherer)

- #6396: Warnings-as-errors not properly flushed in the toplevel
  (Alain Frisch)

- #6401: use proper error reporting for toplevel environment initialization:
  no more Env.Error(_) at start time
  (Gabriel Scherer, Alain Frisch)

- #6468: toplevel now supports backtraces if invoked with OCAMLRUNPARAM=b
  (whitequark and Jake Donham,
   review by Gabriel Scherer and Jacques-Henri Jourdan)

- #6906: wrong error location for unmatched paren with #use in toplevel
  (Damien Doligez, report by Kenichi Asai)

- #6935, #298: crash in debugger when load_printer is given a directory
  (Junsong Li, review by Gabriel Scherer)

- #7081: report preprocessor warnings in the toplevel
  (Valentin Gatien-Baron, review by Jérémie Dimino)

- #7098: Loss of ppx context in toplevel after an exception
  (Alain Frisch, report by whitequark)

- #7101: The toplevel does not close in_channel for libraries specified on
  its command line
  (Alain Frisch)

- #7119: the toplevel does not respect [@@@warning]
  (Alain Frisch, report by Gabriel Radanne)

### Other libraries:

* Unix library: channels created by Unix.in_channel_of_descr or
  Unix.out_channel_of_descr no longer support text mode under Windows.
  Calling [set_binary_mode_{in,out} chan false] on these channels
  now causes an error.
  (Xavier Leroy)

- #4023 and #68: add Unix.sleepf (sleep with sub-second resolution)
  (Evgenii Lepikhin and Xavier Leroy)

* Protect Unix.sleep against interruptions by handled signals.
  Before, a handled signal could cause Unix.sleep to return early.
  Now, the sleep is restarted until the given time is elapsed.
  (Xavier Leroy)

* #6120, #462: implement Unix.symlink and Unix.readlink on
  Windows. Unix.symlink has a new optional argument to_dir (ignored on
  non-native Windows platforms). stat functions reimplemented to avoid
  buggy Microsoft CRT implementations (native Windows only)
  (David Allsopp, review by Daniel Bünzli)

- #6263: add kind_size_in_bytes and size_in_bytes functions
  to Bigarray module.
  (Runhang Li, review by Mark Shinwell)

- #6289: Unix.utimes uses the current time only if both arguments
    are exactly 0.0.  Also, use sub-second resolution if available.
  (Xavier Leroy, report by Christophe Troestler)

- #6896: serious reimplementation of Big_int.float_of_big_int and
  Ratio.float_of_ratio, ensuring that the result is correctly rounded.
  (Xavier Leroy)

- #6989: in Str library, make sure that all \(...\) groups are binding
    and can be consulted with Str.matched_group.  There used to be
    a limitation to 32 binding groups.
  (Xavier Leroy)

- #7013: spurious wake-up in the Event module
  (Xavier Leroy)

- #7024: in documentation of Str regular expressions, clarify what
    "end of line" means for "^" and "$" regexps.
  (Xavier Leroy, question by Fredrik Lindgren)

- #7209: do not run at_exit handlers in [Unix.create_process] and
  similar functions when the [exec] call fails in the child process
  (Jérémie Dimino)

### OCamldep:

- #286: add support for module aliases
  (Jacques Garrigue)

### Manual:

- #302: The OCaml reference manual is now included in the manual/
  subdirectory of the main OCaml source repository. Contributions to
  the manual are warmly welcome.
  (François Bobot, review by Florian Angeletti)

- #6601: replace strcpy with caml_strdup in sample code
  (Christopher Zimmermann)

- #6676: ongoing simplification of the "Language Extensions" section
  (Alain Frisch, John Whitington)

- #6898: Update win32 support documentation of the Unix library
  (Damien Doligez, report by Daniel Bünzli)

- #7092, #379: Add missing documentation for new 4.03 features
  (Florian Angeletti)

- #7094, #468, #551: add new section 8.5 to document warnings
  The general idea is to document warnings that may require explanations.
  Currently documented warnings are:
  - 52: Fragile constant pattern.
  - 57: Ambiguous or-pattern variables under guard
  (Florian Angeletti and Gabriel Scherer)

- #7109, #380: Fix bigarray documentation layout
  (Florian Angeletti, Leo White)

### Bug fixes:

- #3612: memory leak in bigarray read from file
  (Pierre Chambart, report by Gary Huber)

* #4166, #6956: force linking when calling external C primitives
  (Jacques Garrigue, reports by Markus Mottl and Christophe Troestler)

* #4466, #5325: under Windows, concurrent read and write operations
    on the same socket could block unexpectedly.  Fixed by keeping sockets
    in asynchronous mode rather than creating them in synchronous mode.
  (Xavier Leroy)

* #4539: change exception string raised when comparing functional values
  May break programs matching on the string argument of Invalid_argument.
  Matching on the string argument of Invalid_argument or Failure is a
  programming mistake: these strings may change in future versions.
  (Nicolas Braud-Santoni, report by Eric Cooper)

- #4832: Filling bigarrays may block out runtime
  (Markus Mottl)

- #5663: program rejected due to nongeneralizable type variable that
    appears nowhere
  (Jacques Garrigue, report by Stephen Weeks)

- #5780: report more informative type names in GADTs error messages
  (Jacques Garrigue, report by Sebastien Furic)

- #5887: move the byterun/*.h headers to byterun/caml/*.h to avoid header
    name clashes
  (Jérôme Vouillon and Adrien Nader and whitequark)

* #6081: ocaml now adds script's directory to search path, not current
    directory
  (Thomas Leonard and Damien Doligez)

- #6108, #6802: fail cleanly if dynlink.cma or ocamltoplevel.cma
    are loaded inside the toplevel loop.
  (Xavier Leroy)

- #6171: Confusing error message when a type escapes its scope.
  (Jacques Garrigue and Leo White, report by John Whitington)

- #6340: Incorrect handling of \r when processing "Windows" source files
  (Damien Doligez, report by David Allsopp)

- #6342: Incorrect error message when type constraints differ
  (Alain Frisch, report by Philippe Wang)

* #6521: {Bytes,Char,String}.escaped were locale-dependent
  we now escape all non-ASCII-printable instead of a locale-dependent subset.
  (Damien Doligez, report by Jun Furuse)

- #6526: ocamllex should not warn on unescaped newline inside comments
  (Damien Doligez, report by user 'dhekir')

- #6341: ocamldoc -colorize-code adds spurious <br> tags to <pre> blocks
  (Maxence Guesdon, report by Damien Doligez)

- #6560: Wrong failure message for {Int32,Int64,NativeInt}.of_string
  It reported (Failure "int_of_string"), now "Int32.of_string" etc.
  (Maxime Dénès and Gabriel Scherer)

- #6648: show_module should indicate its elision
  (Jacques Garrigue, report by Leo White)

- #6650: Cty_constr not handled correctly by Subst
  (Jacques Garrigue, report by Leo White)

- #6651: Failing component lookup
  (Jacques Garrigue, report by Leo White)

* #6664: Crash when finalising lazy values of the wrong type.
  (Damien Doligez)

- #6672: Unused variance specification allowed in with constraint
  (Jacques Garrigue, report by Leo White)

- #6677: Allow to disable warning 39 (useless "rec") with [@ocaml.warning]
  applied to the first value binding of the would-be "rec" declaration
  (Alain Frisch, report by Jun Furuse)

- #6744: Univars can escape through polymorphic variants (partial fix)
  (Jacques Garrigue, report by Leo White)

- #6752: Extensible variant types and scope escaping
  A side-effect of the fix is that (ocamlc -i) sometimes reports
  (type-sound) invalid signature, with a type used before its declaration.
  (Jacques Garrigue, report by Maxence Guesdon)

- #6762: improve warning 45 in presence of re-exported type definitions
  (Warning 45: open statement shadows the constructor)
  (Alain Frisch, report by Olivier Andrieu)

- #6776: Failure to kill the "tick" thread, segfault when exiting the runtime
  (Damien Doligez, report by Thomas Braibant)

- #6780: Poor error message for wrong -farch and -ffpu options (ocamlopt, ARM)
  (Xavier Leroy, report by whitequark)

- #6805: Duplicated expression in case of hole in a non-failing switch.
  (Luc Maranget)

* #6808: the parsing of OCAMLRUNPARAM is too lax
  (Damien Doligez)

- #6874: Inefficient code generated for module function arguments
  (Jacques Garrigue, report by Markus Mottl)

- #6888: The list command of ocamldebug uses the wrong file
  (Damien Doligez, report by Pierre-Marie Pédrot)

- #6897: Bad error message for some pattern matching on extensible variants
  (Alain Frisch, report by Gabriel Radanne)

- #6899: Optional parameters and non generalizable type variables
  (Thomas Refis and Leo White)

- #6907: Stack overflow printing error in class declaration
  (Jacques Garrigue, report by Ivan Gotovchits)

- #6931: Incorrect error message on type error inside record construction
  (Damien Doligez, report by Leo White)

- #6938: fix regression on "%047.27{l,L,n}{d,i,x,X,o,u}"
  (Benoît Vaugon, report by Arduino Cascella)

- #6944: let module X = Path in … is not typed as a module alias
  (Jacques Garrigue, report by Frédéric Bour)

- #6945 and #227: protect Sys and Unix functions against string
    arguments containing the null character '\000'
  (Simon Cruanes and Xavier Leroy, report by Daniel Bünzli)

- #6946: Uncaught exception with wrong type for "%ignore"
  (Jacques Garrigue, report by Leo White)

- #6954: Infinite loop in type checker with module aliases
  (Jacques Garrigue, report by Markus Mottl)

- #6972, #276: 4.02.3 regression on documentation comments in .cmt files
  (Leo White, report by Olivier Andrieu)

- #6977: String literals in comments interpret escape sequences
  (Damien Doligez, report by Daniel Bünzli and David Sheets)

- #6980: Assert failure from polymorphic variants and existentials
  (Jacques Garrigue, report by Leo White)

- #6981: Ctype.Unify(_) with associated functor arg referring to previous one
  (Jacques Garrigue, report by Nicholas Labich)

- #6982: unexpected type error when packing a module alias
  (Jacques Garrigue, report by Valentin Gatien-Baron)

- #6985: `module type of struct include Bar end exposes
           %s#row when Bar contains private row types
  (Jacques Garrigue, report by Nicholas Labich)

- #6992: Segfault from bug in GADT/module typing
  (Jacques Garrigue, report by Stephen Dolan)

- #6993: Segfault from recursive modules violating exhaustiveness assumptions
  (Jacques Garrigue, report by Stephen Dolan)

- #6998: Typer fails reading unnecessary cmis with -no-alias-deps and -w -49
  (Leo White, report by Valentin Gatien-Baron)

- #7003: String.sub may cause segmentation fault on sizes above 2^31
  (Damien Doligez, report by Radek Micek)

- #7008: Fatal error in ocamlc with empty compilation unit name
  (Damien Doligez, report by Cesar Kunz)

- #7012: Variable name forgotten when it starts with a capital letter
  (Jacques Garrigue, Gabriel Scherer,
   report by Thomas Leonard and Florian Angeletti)

- #7016: fix Stack overflow in GADT typing
  Note: Equi-recursive types are considered when checking GADT pattern
  exhaustiveness, even when -rectypes is not used.
  (Jacques Garrigue, report by Mikhail Mandrykin)

- #7030: libasmrun_shared.so fails to build on SPARC Solaris
  (report and fix by Patrick Star)

- #7036: Module alias is not taken into account when checking module
  type compatibility (in a class type)
  (Jacques Garrigue)

- #7037: more reproducible builds, don't put temp file names into objects
  (Xavier Leroy)

- #7038: out of memory condition in caml_io_mutex_lock
  (Xavier Leroy, report by Marc Lasson)

- #7039: Unix.getsockname returns garbage for unnamed PF_UNIX sockets
  (Xavier Leroy)

- #7042 and #295: CSE optimization confuses the FP literals +0.0 and -0.0
  (Xavier Leroy)

- #7075: Fix repetitions in ocamldoc generated documentation
  (Florian Angeletti)

- #7082: Object type in recursive module's `with` annotation
  (Jacques Garrigue and Alain Frisch, report by Nicholas Labich)

- #7096: ocamldoc uses an incorrect subscript/superscript style
  (Gabriel Scherer, report by user 'pierpa')

- #7108: ocamldoc, have -html preserve custom/extended html generators
  (Armaël Guéneau)

- #7111: reject empty let bindings instead of printing incorrect syntax
  (Jérémie Dimino)

* #7113: -safe-string can break GADT compatibility check
  bytes and string are now considered compatible even with -safe-string,
  which may break exhaustivity for code assuming they were disjoint
  (Jacques Garrigue, report by Jeremy Yallop)

- #7115: shadowing in a branch of a GADT match breaks unused variable warning
  (Alain Frisch, report by Valentin Gatien-Baron)

- #7133, #450: generate local jump labels on OS X
  (Bart Jacobs)

- #7135: only warn about ground coercions in -principal mode
  (Jacques Garrigue, report by Jeremy Yallop)

* #7152: Typing equality involving non-generalizable type variable
  A side-effect of the fix is that, for deeply nested non generalizable
  type variables, having an interface file may no longer be sufficient,
  and you may have to add a local type annotation (cf #7313)
  (Jacques Garrigue, report by François Bobot)

- #7160: Type synonym definitions can weaken gadt constructor types
  (Jacques Garrigue, report by Mikhail Mandrykin)

- #7181: Misleading error message with GADTs and polymorphic variants
  (Jacques Garrigue, report by Pierre Chambart)

- #7182: Assertion failure with recursive modules and externals
  (Jacques Garrigue, report by Jeremy Yallop)

- #7196: "let open" is not correctly pretty-printed to the left of a ';'
  (Gabriel Scherer, report by Christophe Raffalli)

- #7214: Assertion failure in Env.add_gadt_instances
  (Jacques Garrigue, report by Stephen Dolan)

- #7220: fix a memory leak when using both threads and exception backtraces
  (Gabriel Scherer, review by François Bobot, report by Rob Hoes)

- #7222: Escaped existential type
  (Jacques Garrigue, report by Florian Angeletti)

- #7230: Scrutinee discarded in match with only refutation cases
  (Jacques Garrigue, report by Jeremy Yallop)

- #7234: Compatibility check wrong for abstract type constructors
  (Jacques Garrigue, report by Stephen Dolan)

- #7324: OCaml 4.03.0 type checker dies with an assert failure when
  given some cyclic recursive module expression
  (Jacques Garrigue, report by jmcarthur)

- #7368: Manual major GC fails to compact the heap
  (Krzysztof Pszeniczny)

- #205: Clear caml_backtrace_last_exn before registering as root
  (report and fix by Frédéric Bour)

- #220: minor -dsource error on recursive modules
  (Hongbo Zhang)

- #228: fix a dangling internal pointer in (bytecode) debug_info
  (Gabriel Scherer and Mark Shinwell and Xavier Leroy)

- #233: Make CamlinternalMod.init_mod robust to optimization
  (Pierre Chambart, Mark Shinwell)

- #249: fix a few hardcoded ar commands
  (Daniel Bünzli)

- #251: fix cross-compilation with ocamldoc enabled
  (whitequark)

- #280: Fix stdlib dependencies for .p.cmx
  (Pierre Chambart, Mark Shinwell)

- #283: Fix memory leaks in intern.c when OOM is raised
  (Marc Lasson, review by Alain Frisch)

- #22: Fix the cleaning of weak pointers. In very rare cases
  accessing a value during the cleaning of the weak pointers could
  result in the value being removed from one weak arrays and kept in
  another one. That breaks the property that a value is removed from a
  weak pointer only when it is dead and garbage collected.
  (François Bobot, review by Damien Doligez)

- #313: Prevent quadratic cases in CSE
  (Pierre Chambart, review by Xavier Leroy)

- #6795, #6996: Make ocamldep report errors passed in
  [%ocaml.error] extension points
  (Jérémie Dimino)

- #355: make ocamlnat build again
  (Jérémie Dimino, Thomas Refis)

- #405: fix compilation under Visual Studio 2015
  (David Allsopp)

- #441: better type error location in presence of type constraints
  (Thomas Refis, report by Arseniy Alekseyev)

- #477: reallow docstrings inside object types, and inside polymorphic
  variant and arrow types
  (Thomas Refis)

### Features wishes:

- #4518, #29: change location format for reporting errors in ocamldoc
  (Sergei Lebedev)

- #4714: List.cons

- #5418 (comments) : generate dependencies with $(CC) instead of gcc
  (Damien Doligez, report by Michael Grünewald)

- #6167: OCAMLPARAM support for disabling PIC generation ("pic=0")
  (Gabor Pali)

- #6367, #25: introduce Asttypes.arg_label to encode labelled arguments
  (Frédéric Bour and Jacques Garrigue)

- #6452, #140: add internal support for custom printing formats
  (Jérémie Dimino)

- #6611: remove the option wrapper on optional arguments in the syntax tree
  (Alain Frisch, review by Damien Doligez, request by whitequark)

- #6635: support M.[], M.(), M.{< >} and M.[| |]
  (Jeremy Yallop, review by Gabriel Radanne)

- #6691: install .cmt[i] files for stdlib and compiler-libs
  (David Sheets, request by Gabriel Radanne)

- #6722: compatibility with x32 architecture (x86-64 in ILP32 mode).
  ocamlopt is not supported, but bytecode compiles cleanly.
  (Adam Borowski and Xavier Leroy)

- #6742: remove duplicate virtual_flag information from Tstr_class
  (Gabriel Radanne and Jacques Garrigue)

- #6719: improve Buffer.add_channel when not enough input is available
  (Simon Cruanes)

* #6816: reject integer and float literals directly followed by an identifier.
  This was previously read as two separate tokens.
  [let abc = 1 in (+) 123abc] was accepted and is now rejected.
  (Hugo Heuzard)

- #6876: improve warning 6 by listing the omitted labels.
  (Warning 6: Label omitted in function application)
  (Eyyüb Sari)

- #6924: tiny optim to avoid some spilling of floats in x87
  (Alain Frisch)

- #111: `(f [@taillcall]) x y` warns if `f x y` is not a tail-call
  (Simon Cruanes)

- #118: ocamldep -allow-approx: fallback to a lexer-based approximation
  (Frédéric Bour)

- #137: add untypeast.ml (in open recursion style) to compiler-libs
  (Gabriel Radanne)

- #142: add a CAMLdrop macro for undoing CAMLparam*/CAMLlocal*
  (Thomas Braibant and Damien Doligez)

- #145: speeedup bigarray access by optimizing Cmmgen.bigarray_indexing
  (Vladimir Brankov, review by Gabriel Scherer)

- #147: [type 'a result = Ok of 'a | Error of 'b] in Pervasives
  (Yaron Minsky)

- #156, #279: optimize caml_frame_descriptors realloc (dynlink speedup)
  (Pierre Chambart, Alain Frisch,
   review by François Bobot, Xavier Leroy and Damien Doligez)

- #165, #221: fix windows compilation warnings
  (Bernhard Schommer, Gabriel Scherer, report by Alain Frisch)

* #170: Parse arbitrary precision integers.
  Accept a single [A-Za-z] as modifier for integers (generalizing 'l','L','n')
  and floats.
  May cause breakage (ie. ppx preprocessor) because of changes in the parsetree.
  This changes #6816 a little bit by reading the literal [123a] as a single
  token that can later be rewritten by a ppx preprocessor.
  (Hugo Heuzard)

- #189: Added .dylib and .so as extensions for ocamlmklib
  (Edgar Aroutiounian, whitequark)

- #191: Making gc.h and some part of memory.h public
  (Thomas Refis)

- #196: Make [Thread.id] and [Thread.self] [noalloc]
  (Clark Gaebel)

- #237: a CONTRIBUTING document
  (François Bobot, Gabriel Scherer, review by Xavier Leroy)

- #245: remove a few remaining French comments
  (Florian Angeletti)

- #252: improve build instructions in MSVC Windows README
  (Philip Daian)

- #308: add experimental support for NetBSD/arm (verified on RaspberryPi)
  (Rich Neswold)

- #335: Type error messages specifies if a type is abstract
  because no corresponding cmi could be found.
  (Hugo Heuzard)

- #365: prevent printing just a single type variable on one side
  of a type error clash.
  (Hugo Heuzard)

- #383: configure: define _ALL_SOURCE for build on AIX7.1
  (tkob)

- #401: automatically retry failed test directories in the testsuite
  (David Allsopp)

- #451: an optional 'parallel' target in testsuite/Makefile using the
  GNU parallel tool to run tests in parallel.
  (Gabriel Scherer)

- #555: ensure that register typing constraints are respected at
  join points in the control flow graph
  (Mark Shinwell, debugging & test case by Arseniy Alekseyev and Leo White,
    code review by Xavier Leroy)

### Build system:

- #388: FlexDLL added as a Git submodule and bootstrappable with the compiler
  (David Allsopp)

OCaml 4.02.3 (27 Jul 2015):
---------------------------

Bug fixes:
- #6908: Top-level custom printing for GADTs: interface change in 4.02.2
  (Grégoire Henry, report by Jeremy Yallop)
- #6919: corrupted final_table
  (ygrek)
- #6926: Regression: ocamldoc lost unattached comment
  (Damien Doligez, report by François Bobot)
- #6930: Aliased result type of GADT constructor results in assertion failure
  (Jacques Garrigue)

Feature wishes:
- #6691: install .cmt[i] files for stdlib and compiler-libs
  (David Sheets, request by Gabriel Radanne)
- #37: New primitive: caml_alloc_dummy_function
  (Hugo Heuzard)

OCaml 4.02.2 (17 Jun 2015):
---------------------------

(Changes that can break existing programs are marked with a "*")

Language features:
- #6583: add a new class of binary operators with the same syntactic
  precedence as method calls; these operators start with # followed
  by a non-empty sequence of operator symbols (for instance #+, #!?).
  It is also possible to use '#' as part of these extra symbols
  (for instance ##, or #+#); this is rejected by the type-checker,
  but can be used e.g. by ppx rewriters.
  (Alain Frisch, request by Gabriel Radanne)
* #6016: add a "nonrec" keyword for type declarations
  (Jérémie Dimino)
* #6612, #152: change the precedence of attributes in type declarations
  (Jérémie Dimino)

Compilers:
- #6600: make -short-paths faster by building the printing map
  incrementally
  (Jacques Garrigue)
- #6642: replace $CAMLORIGIN in -ccopt with the path to cma or cmxa
  (whitequark, Gabriel Scherer, review by Damien Doligez)
- #6797: new option -output-complete-obj
  to output an object file with included runtime and autolink libraries
  (whitequark)
- #6845: -no-check-prims to tell ocamlc not to check primitives in runtime
  (Alain Frisch)
- #149: Attach documentation comments to parse tree
  (Leo White)
- #159: Better locations for structure/signature items
  (Leo White)

Toplevel and debugger:
- #5958: generalized polymorphic #install_printer
  (Pierre Chambart and Grégoire Henry)

OCamlbuild:
- #6237: explicit "infer" tag to control or disable menhir --infer
  (Hugo Heuzard)
- #6625: pass -linkpkg to files built with -output-obj.
  (whitequark)
- #6702: explicit "linkpkg" and "dontlink(foo)" flags
  (whitequark, Gabriel Scherer)
- #6712: Ignore common VCS directories
  (whitequark)
- #6720: pass -g to C compilers when tag 'debug' is set
  (whitequark, Gabriel Scherer)
- #6733: add .byte.so and .native.so targets to pass
  -output-obj -cclib -shared.
  (whitequark)
- #6733: "runtime_variant(X)" to pass -runtime-variant X option.
  (whitequark)
- #6774: new menhir-specific flags "only_tokens" and "external_tokens(Foo)"
  (François Pottier)

Libraries:
- #6285: Add support for nanosecond precision in Unix.stat()
  (Jérémie Dimino, report by user 'gfxmonk')
- #6781: Add higher baud rates to Unix termios
  (Damien Doligez, report by Berke Durak)
- #6834: Add Obj.{first,last}_non_constant_constructor_tag
  (Mark Shinwell, request by Gabriel Scherer)

Runtime:
- #6078: Release the runtime system when calling caml_dlopen
  (Jérémie Dimino)
- #6675: GC hooks
  (Damien Doligez and Roshan James)

Build system:
- #5418 (comments) : generate dependencies with $(CC) instead of gcc
  (Damien Doligez and Michael Grünewald)
- #6266: Cross compilation for iOs, Android etc
  (whitequark, review by Damien Doligez and Mark Shinwell)

Installation procedure:
- Update instructions for x86-64 PIC mode and POWER architecture builds
  (Mark Shinwell)

Bug fixes:
- #5271: Location.prerr_warning is hard-coded to use Format.err_formatter
  (Damien Doligez, report by Rolf Rolles)
- #5395: OCamlbuild mishandles relative symlinks and include paths
  (Damien Doligez, report by Didier Le Botlan)
- #5822: wrong value of Options.ext_dll on windows
  (Damien Doligez and Daniel Weil)
- #5836, #6684: printing lazy values in ocamldebug may segfault
  (Gabriel Scherer, request by the Coq team)
- #5887: move the byterun/*.h headers to byterun/caml/*.h to avoid
  header name clashes
  (Jérôme Vouillon and Adrien Nader and whitequark)
- #6281: Graphics window does not acknowledge second click (double click)
  (Kyle Headley)
- #6490: incorrect backtraces in gdb on AArch64.  Also fixes incorrect
  backtraces on 32-bit ARM.
  (Mark Shinwell)
- #6573: extern "C" for systhreads/threads.h
  (Mickaël Delahaye)
- #6575: Array.init evaluates callback although it should not do so
  (Alain Frisch, report by Gerd Stolpmann)
- #6607: The manual doesn't mention 0x200 flag for OCAMLRUNPARAM=v
  (Alain Frisch)
- #6616: allow meaningful use of -use-runtime without -custom.
  (whitequark)
- #6617: allow android build with pthreads support (since SDK r10c)
  (whitequark)
- #6626: ocamlbuild on cygwin cannot find ocamlfind
  (Gergely Szilvasy)
- #6628: Configure script rejects legitimate arguments
  (Michael Grünewald, Damien Doligez)
- #6630: Failure of tests/prim-bigstring/{big,}string.ml on big-endian
  architectures
  (Pierre Chambart, testing by Mark Shinwell)
- #6640: ocamlbuild: wrong "unused tag" warning on "precious"
  (report by user 'william')
- #6652: ocamlbuild -clean does not print a newline after output
  (Damien Doligez, report by Andi McClure)
- #6658: cross-compiler: version check not working on OS X
  (Gerd Stolpmann)
- #6665: Failure of tests/asmcomp on sparc
  (Stéphane Glondu)
- #6667: wrong implementation of %bswap16 on ARM64
  (Xavier Leroy)
- #6669: fix 4.02 regression in toplevel printing of lazy values
  (Leo White, review by Gabriel Scherer)
- #6671: Windows: environment variable 'TZ' affects Unix.gettimeofday
  (Mickaël Delahaye and Damien Doligez)
- #6680: Missing parentheses in warning about polymorphic variant value
  (Jacques Garrigue and Gabriel Scherer, report by Philippe Veber)
- #6686: Bug in [subst_boxed_number]
  (Jérémie Dimino, Mark Shinwell)
- #6690: Uncaught exception (Not_found) with (wrong) wildcard or unification
  type variable in place of a local abstract type
  (Jacques Garrigue, report by Mikhail Mandrykin)
- #6693 (part two): Incorrect relocation types in x86-64 runtime system
  (whitequark, review by Jacques-Henri Jourdan, Xavier Leroy and Mark Shinwell)
- #6717: Pprintast does not print let-pattern attributes
  (Gabriel Scherer, report by whitequark)
- #6727: Printf.sprintf "%F" misbehavior
  (Benoît Vaugon, report by Vassili Karpov)
- #6747: ocamlobjinfo: missing symbol caml_plugin_header due to underscore
  (Damien Doligez, Maverick Woo)
- #6749: ocamlopt returns n for (n mod 1) instead of 0
  (Mark Shinwell and Jérémie Dimino)
- #6753: Num.quo_num and Num.mod_num incorrect for some negative arguments
  (Xavier Leroy)
- #6758: Ocamldoc "analyse_module: parsetree and typedtree don't match"
  (Damien Doligez, report by user 'maro')
- #6759: big_int_of_string incorrectly parses some hexa literals
  (Damien Doligez, report by Pierre-yves Strub)
- #6763: #show with -short-paths doesn't select shortest type paths
  (Jacques Garrigue, report by David Sheets)
- #6768: Typechecker overflow the stack on cyclic type
  (Jacques Garrigue, report by user 'darktenaibre')
- #6770: duplicate of #6686
- #6772: asmrun/signals_asm.c doesn't compile on NetBSD/i386
  (Kenji Tokudome)
- #6775: Digest.file leaks file descriptor on error
  (Valentin Gatien-Baron)
- #6779: Cross-compilers cannot link bytecode using custom primitives
  (Damien Doligez, request by whitequark)
- #6787: Soundness bug with polymorphic variants
  (Jacques Garrigue, with help from Leo White and Grégoire Henry,
   report by Michael O'Connor)
- #6790: otherlibs should be built with -g
  (Damien Doligez, report by whitequark)
- #6791: "%s@[", "%s@{" regression in Scanf
  (Benoît Vaugon)
- #6793: ocamlbuild passes nonsensical "-ocamlc ..." commands to menhir
  (Gabriel Scherer, report by Damien Doligez)
- #6799: include guards missing for unixsupport.h and other files
  (Andreas Hauptmann)
- #6810: Improve documentation of Bigarray.Genarray.map_file
  (Mark Shinwell and Daniel Bünzli)
- #6812: -short-paths and -no-alias-deps can create inconsistent assumptions
  (Jacques Garrigue, report by Valentin Gatien-Baron)
- #6817: GADT exhaustiveness breakage with modules
  (Leo White, report by Pierre Chambart)
- #6824: fix buffer sharing on partial application of Format.asprintf
  (Gabriel Scherer, report by Alain Frisch)
- #6831: Build breaks for -aspp gcc on solaris-like OSs
  (John Tibble)
- #6836: Assertion failure using -short-paths
  (Jacques Garrigue, report by David Sheets)
- #6837: Build profiling libraries on FreeBSD and NetBSD x86-64
  (Mark Shinwell, report by Michael Grünewald)
- #6841: Changing compilation unit name with -o breaks ocamldebug
  (Jacques Garrigue, report by Jordan Walke)
- #6842: export Typemod.modtype_of_package
- #6843: record weak dependencies even when the .cmi is missing
  (Leo White, Gabriel Scherer)
- #6849: Inverted pattern unification error
  (Jacques Garrigue, report by Leo White)
- #6857: __MODULE__ doesn't give the current module with -o
  (Jacques Garrigue, report by Valentin Gatien-Baron)
- #6862: Exhaustiveness check wrong for class constructor arguments
  (Jacques Garrigue)
- #6869: Improve comment on [Hashtbl.hash_param]
  (Mark Shinwell, report by Jun Furuse)
- #6870: Unsoundness when -rectypes fails to detect non-contractive type
  (Jacques Garrigue, report by Stephen Dolan)
- #6872: Type-directed propagation fails to disambiguate variants
  that are also exception constructors
  (Jacques Garrigue, report by Romain Beauxis)
- #6878: AArch64 backend generates invalid asm: conditional branch
  out of range (Mark Shinwell, report by Richard Jones, testing by Richard
  Jones and Xavier Leroy, code review by Xavier Leroy and Thomas Refis)
- #6879: Wrong optimization of 1 mod n
  (Mark Shinwell, report by Jean-Christophe Filliâtre)
- #6884: The __CYGWIN32__ #define should be replaced with __CYGWIN__
  (Adrien Nader)
- #6886: -no-alias-deps allows to build self-referential compilation units
  (Jacques Garrigue, report by Valentin Gatien-Baron)
- #6889: ast_mapper fails to rewrite class attributes
  (Sébastien Briais)
- #6893: ocamlbuild:  "tag not used" warning when using (p)dep
  (Gabriel Scherer, report by Christiano Haesbaert)
- #143: fix getsockopt behaviour for boolean socket options
  (Anil Madhavapeddy and Andrew Ray)
- #190: typo in pervasives
  (Guillaume Bury)
- Misplaced assertion in major_gc.c for no-naked-pointers mode
  (Stephen Dolan, Mark Shinwell)

Feature wishes:
- #6452, #140: add internal support for custom printing formats
  (Jérémie Dimino)
- #6641: add -g, -ocamlcflags, -ocamloptflags options to ocamlmklib
  (whitequark)
- #6693: also build libasmrun_shared.so and lib{asm,caml}run_pic.a
  (whitequark, review by Mark Shinwell)
- #6842: export Typemod.modtype_of_package
  (Jacques Garrigue, request by Jun Furuse)
- #139: more versatile specification of locations of .annot
  (Christophe Troestler, review by Damien Doligez)
- #171: allow custom warning printers / catchers
  (Benjamin Canou, review by Damien Doligez)
- #191: Making gc.h and some part of memory.h public
  (Thomas Refis)

OCaml 4.02.1 (14 Oct 2014):
---------------------------

(Changes that can break existing programs are marked with a "*")

Standard library:
* Add optional argument ?limit to Arg.align.

Bug Fixes:
- #4099: Bug in Makefile.nt: won't stop on error
  (George Necula)
- #6181: Improve MSVC build
  (Chen Gang)
- #6207: Configure doesn't detect features correctly on Haiku
  (Jessica Hamilton)
- #6466: Non-exhaustive matching warning message for open types is confusing
  (whitequark)
- #6529: fix quadratic-time algorithm in Consistbl.extract.
  (Xavier Leroy, Alain Frisch, relase-worthy report by Kate Deplaix)
- #6530: Add stack overflow handling for native code (OpenBSD i386 and amd64)
  (Cristopher Zimmermann)
- #6533: broken semantics of %(%) when substituted by a box
  (Benoît Vaugon, report by Boris Yakobowski)
- #6534: legacy support for %.10s
  (Benoît Vaugon, Gabriel Scherer, report by Nick Chapman)
- #6536: better documentation of flag # in format strings
  (Damien Doligez, report by Nick Chapman)
- #6544: Bytes and CamlinternalFormat missing from threads stdlib.cma
  (Christopher Zimmermann)
- #6546: -dsource omits parens for `List ((`String "A")::[]) in patterns
  (Gabriel Scherer, report by whitequark)
- #6547: __MODULE__ aborts the compiler if the module name cannot be inferred
  (Jacques Garrigue, report by Kaustuv Chaudhuri)
- #6549: Debug section is sometimes not readable when using -pack
  (Hugo Heuzard, review by Gabriel Scherer)
- #6553: Missing command line options for ocamldoc
  (Maxence Guesdon)
- #6554: fix race condition when retrieving backtraces
  (Jérémie Dimino, Mark Shinwell).
- #6557: String.sub throws Invalid_argument("Bytes.sub")
  (Damien Doligez, report by Oliver Bandel)
- #6562: Fix ocamldebug module source lookup
  (Leo White)
- #6563: Inclusion of packs failing to run module initializers
  (Jacques Garrigue, report by Mark Shinwell)
- #6564: infinite loop in Mtype.remove_aliases
  (Jacques Garrigue, report by Mark Shinwell)
- #6565: compilation fails with Env.Error(_)
  (Jacques Garrigue and Mark Shinwell)
- #6566: -short-paths and signature inclusion errors
  (Jacques Garrigue, report by Mark Shinwell)
- #6572: Fatal error with recursive modules
  (Jacques Garrigue, report by Quentin Stievenart)
- #6575: Array.init evaluates callback although it should not do so
  (Alain Frisch, report by Gerd Stolpmann)
- #6578: Recursive module containing alias causes Segmentation fault
  (Jacques Garrigue)
- #6581: Some bugs in generative functors
  (Jacques Garrigue, report by Mark Shinwell)
- #6584: ocamldep support for "-open M"
  (Gabriel Scherer, review by Damien Doligez, report by Hezekiah M. Carty)
- #6588: Code generation errors for ARM
  (Mark Shinwell, Xavier Leroy)
- #6590: Improve Windows (MSVC and mingw) build
  (Chen Gang)
- #6599: ocamlbuild: add -bin-annot when using -pack
  (Christopher Zimmermann)
- #6602: Fatal error when tracing a function with abstract type
  (Jacques Garrigue, report by Hugo Herbelin)
- ocamlbuild: add an -ocamlmklib option to change the ocamlmklib command
  (Jérôme Vouillon)

OCaml 4.02.0 (29 Aug 2014):
---------------------------

(Changes that can break existing programs are marked with a "*")

Language features:
- Attributes and extension nodes
  (Alain Frisch)
- Generative functors (#5905)
  (Jacques Garrigue)
* Module aliases
  (Jacques Garrigue)
* Alternative syntax for string literals {id|...|id} (can break comments)
  (Alain Frisch)
- Separation between read-only strings (type string) and read-write byte
  sequences (type bytes). Activated by command-line option -safe-string.
  (Damien Doligez)
- #6318: Exception cases in pattern matching
  (Jeremy Yallop, backend by Alain Frisch)
- #5584: Extensible open datatypes
  (Leo White)

Build system for the OCaml distribution:
- Use -bin-annot when building.
- Use GNU make instead of portable makefiles.
- Updated build instructions for 32-bit Mac OS X on Intel hardware.

Shedding weight:
* Removed Camlp4 from the distribution, now available as third-party software.
* Removed Labltk from the distribution, now available as a third-party library.

Type system:
* #6235: Keep typing of pattern cases independent in principal mode
  (i.e. information from previous cases is no longer used when typing
  patterns; cf. '#6235' in testsuite/test/typing-warnings/records.ml)
  (Jacques Garrigue)
- Allow opening a first-class module or applying a generative functor
  in the body of a generative functor. Allow it also in the body of
  an applicative functor if no types are created
  (Jacques Garrigue, suggestion by Leo White)
* Module aliases are now typed in a specific way, which remembers their
  identity. Compiled interfaces become smaller, but may depend on the
  original modules. This also changes the signature inferred by
  "module type of".
  (Jacques Garrigue, feedback from Leo White, Mark Shinwell and Nick Chapman)
- #6331: Slight change in the criterion to distinguish private
  abbreviations and private row types: create a private abbreviation for
  closed objects and fixed polymorphic variants.
  (Jacques Garrigue)
* #6333: Compare first class module types structurally rather than
  nominally. Value subtyping allows module subtyping as long as the internal
  representation is unchanged.
  (Jacques Garrigue)

Compilers:
- More aggressive constant propagation, including float and
  int32/int64/nativeint arithmetic.  Constant propagation for floats
  can be turned off with option -no-float-const-prop, for codes that
  change FP rounding modes at run-time.
  (Xavier Leroy)
- New back-end optimization pass: common subexpression elimination (CSE).
  (Reuses results of previous computations instead of recomputing them.)
  (Xavier Leroy)
- New back-end optimization pass: dead code elimination.
  (Removes arithmetic and load instructions whose results are unused.)
  (Xavier Leroy)
- #6269: Optimization of sequences of string patterns
  (Benoît Vaugon and Luc Maranget)
- Experimental native code generator for AArch64 (ARM 64 bits)
  (Xavier Leroy)
- #6042: Optimization of integer division and modulus by constant divisors
  (Xavier Leroy and Phil Denys)
- Add "-open" command line flag for opening a single module before typing
  (Leo White, Mark Shinwell and Nick Chapman)
* "-o" now sets module name to the output file name up to the first "."
  (it also applies when "-o" is not given, i.e. the module name is then
   the input file name up to the first ".")
  (Leo White, Mark Shinwell and Nick Chapman)
* #5779: better sharing of structured constants
  (Alain Frisch)
- #5817: new flag to keep locations in cmi files
  (Alain Frisch)
- #5854: issue warning 3 when referring to a value marked with
  the [@@ocaml.deprecated] attribute
  (Alain Frisch, suggestion by Pierre-Marie Pédrot)
- #6017: a new format implementation based on GADTs
  (Benoît Vaugon and Gabriel Scherer)
* #6203: Constant exception constructors no longer allocate
  (Alain Frisch)
- #6260: avoid unnecessary boxing in let
  (Vladimir Brankov)
- #6345: Better compilation of optional arguments with default values
  (Alain Frisch, review by Jacques Garrigue)
- #6389: ocamlopt -opaque option for incremental native compilation
  (Pierre Chambart, Gabriel Scherer)

Toplevel interactive system:
- #5377: New "#show_*" directives
  (ygrek, Jacques Garrigue and Alain Frisch)

Runtime system:
- New configure option "-no-naked-pointers" to improve performance by
  avoiding page table tests during block darkening and the marking phase
  of the major GC.  In this mode, all out-of-heap pointers must point at
  things that look like OCaml values: in particular they must have a valid
  header.  The colour of said headers should be black.
  (Mark Shinwell, reviews by Damien Doligez and Xavier Leroy)
- Fixed bug in native code version of [caml_raise_with_string] that could
  potentially lead to heap corruption.
  (Mark Shinwell)
* Blocks initialized by [CAMLlocal*] and [caml_alloc] are now filled with
  [Val_unit] rather than zero.
  (Mark Shinwell)
- Fixed a major performance problem on large heaps (~1GB) by making heap
  increments proportional to heap size by default
  (Damien Doligez)
- #4765: Structural equality treats exception specifically
  (Alain Frisch)
- #5009: efficient comparison/indexing of exceptions
  (Alain Frisch, request by Markus Mottl)
- #6075: avoid using unsafe C library functions (strcpy, strcat, sprintf)
  (Xavier Leroy, reports from user 'jfc' and Anil Madhavapeddy)
- An ISO C99-compliant C compiler and standard library is now assumed.
  (Plus special exceptions for MSVC.)  In particular, emulation code for
  64-bit integer arithmetic was removed, the C compiler must support a
  64-bit integer type.
  (Xavier Leroy)

Standard library:
* Add new modules Bytes and BytesLabels for mutable byte sequences.
  (Damien Doligez)
- #4986: add List.sort_uniq and Set.of_list
  (Alain Frisch)
- #5935: a faster version of "raise" which does not maintain the backtrace
  (Alain Frisch)
- #6146: support "Unix.kill pid Sys.sigkill" under Windows
  (Romain Bardou and Alain Frisch)
- #6148: speed improvement for Buffer
  (John Whitington)
- #6180: efficient creation of uninitialized float arrays
  (Alain Frisch, request by Markus Mottl)
- #6355: Improve documentation regarding finalisers and multithreading
  (Daniel Bünzli, Mark Shinwell)
- Trigger warning 3 for all values marked as deprecated in the documentation.
  (Damien Doligez)

OCamldoc:
- #6257: handle full doc comments for variant constructors and
  record fields
  (Maxence Guesdon, request by ygrek)
- #6274: allow doc comments on object types
  (Thomas Refis)
- #6310: fix ocamldoc's subscript/superscript CSS font size
  (Anil Madhavapeddy)
- #6425: fix generation of man pages
  (Maxence Guesdon, report by Anil Madhavapeddy)

Bug fixes:
- #2719: wrong scheduling of bound checks within a
  try...with Invalid_argument -> _ ...  (Xavier Leroy)
- #4719: Sys.executable_name wrong if executable name contains dots (Windows)
  (Alain Frisch, report by Bart Jacobs)
- #5406 ocamlbuild: "tag 'package' does not expect a parameter"
  (Gabriel Scherer)
- #5598, #6165: Alterations to handling of \013 in source files
  breaking other tools
  (David Allsopp and Damien Doligez)
- #5820: Fix camlp4 lexer roll back problem
  (Hongbo Zhang)
- #5946: CAMLprim taking (void) as argument
  (Benoît Vaugon)
- #6038: on x86-32, enforce 16-byte stack alignment for compatibility
  with recent GCC and Clang.  Win32/MSVC keeps 4-byte stack alignment.
  (Xavier Leroy)
- #6062: Fix a 4.01 camlp4 DELETE_RULE regression caused by commit 13047
  (Hongbo Zhang, report by Christophe Troestler)
- #6173: Typing error message is worse than before
  (Jacques Garrigue and John Whitington)
- #6174: OCaml compiler loops on an example using GADTs (-rectypes case)
  (Jacques Garrigue and Grégoire Henry, report by Chantal Keller)
- #6175: open! was not supported by camlp4
  (Hongbo Zhang)
- #6184: ocamlbuild: `ocamlfind ocamldep` does not support -predicate
  (Kate Deplaix)
- #6194: Incorrect unused warning with first-class modules in patterns
  (Jacques Garrigue, report by Markus Mottl and Leo White)
- #6211: in toplevel interactive use, bad interaction between uncaught
  exceptions and multiple bindings of the form "let x = a let y = b;;".
  (Xavier Leroy)
- #6216: inlining of GADT matches generates invalid assembly
  (Xavier Leroy and Alain Frisch, report by Mark Shinwell)
- #6232: Don't use [mktemp] on platforms where [mkstemp] is available
  (Stéphane Glondu, Mark Shinwell)
- #6233: out-of-bounds exceptions lose their locations on ARM, PowerPC
  (Jacques-Henri Jourdan and Xavier Leroy,
   report and testing by Stéphane Glondu)
- #6235: Issue with type information flowing through a variant pattern
  (Jacques Garrigue, report by Hongbo Zhang)
- #6239: sometimes wrong stack alignment when raising exceptions
           in -g mode with backtraces active
  (Xavier Leroy, report by Yaron Minsky)
- #6240: Fail to expand module type abbreviation during substyping
  (Jacques Garrigue, report by Leo White)
- #6241: Assumed inequality between paths involving functor arguments
  (Jacques Garrigue, report by Jeremy Yallop)
- #6243: Make "ocamlopt -g" more resistant to ill-formed locations
  (Xavier Leroy, report by Pierre-Marie Pédrot)
- #6262: equality of first-class modules take module aliases into account
  (Alain Frisch and Leo White)
- #6268: -DMODEL_$(MODEL) not passed when building asmrun/arm.p.o
  (Peter Michael Green)
- #6273: fix Sys.file_exists on large files (Win32)
  (Christoph Bauer)
- #6275: Soundness bug related to type constraints
  (Jacques Garrigue, report by Leo White)
- #6293: Assert_failure with invalid package type
  (Jacques Garrigue, report by Elnatan Reisner)
- #6300: ocamlbuild -use-ocamlfind conflicts with -ocamlc
  (Gabriel Scherer)
- #6302: bytecode debug information re-read from filesystem every time
  (Jacques-Henri Jourdan)
- #6307: Behavior of 'module type of' w.r.t. module aliases
  (Jacques Garrigue, report by Alain Frisch)
- #6332: Unix.open_process fails to pass empty arguments under Windows
  (Damien Doligez, report Virgile Prevosto)
- #6346: Build failure with latest version of xcode on OSX
  (Jérémie Dimino)
- #6348: Unification failure for GADT when original definition is hidden
  (Leo White and Jacques Garrigue, report by Jeremy Yallop)
- #6352: Automatic removal of optional arguments and sequencing
  (Jacques Garrigue and Alain Frisch)
- #6361: Hashtbl.hash not terminating on some lazy values w/ recursive types
  (Xavier Leroy, report by Leo White)
- #6383: Exception Not_found when using object type in absent module
  (Jacques Garrigue, report by Sébastien Briais)
- #6384: Uncaught Not_found exception with a hidden .cmi file
  (Leo White)
- #6385: wrong allocation of large closures by the bytecode interpreter
  (Xavier Leroy, report by Stephen Dolan)
- #6394: Assertion failed in Typecore.expand_path
  (Alain Frisch and Jacques Garrigue)
- #6405: unsound interaction of -rectypes and GADTs
  (Jacques Garrigue, report by Gabriel Scherer and Benoît Vaugon)
- #6408: Optional arguments given as ~?arg instead of ?arg in message
  (Michael O'Connor)
- #6411: missing libgcc_s_sjlj-1.dll in mingw (add -static-libgcc)
  (Jun Furuse and Alain Frisch, Jonathan Protzenko and Adrien Nader)
- #6436: Typos in @deprecated text in stdlib/arrayLabels.mli
  (John Whitington)
- #6439: Don't use the deprecated [getpagesize] function
  (John Whitington, Mark Shinwell)
- #6441: undetected tail-call in some mutually-recursive functions
  (many arguments, and mutual block mixes functions and non-functions)
  (Stefan Holdermans, review by Xavier Leroy)
- #6443: ocaml segfault when List.fold_left is traced then executed
  (Jacques Garrigue, report by user 'Reventlov')
- #6451: some bugs in untypeast.ml
  (Jun Furuse, review by Alain Frisch)
- #6460: runtime assertion failure with large [| e1;...eN |]
  float array expressions
  (Leo White)
- #6463: -dtypedtree fails on class fields
  (Leo White)
- #6469: invalid -dsource printing of "external _pipe = ...", "Pervasives.(!)"
  (Gabriel Scherer and Damien Doligez, user 'ngunn')
- #6482: ocamlbuild fails when _tags file in unhygienic directory
  (Gabriel Scherer)
- #6502: ocamlbuild spurious warning on "use_menhir" tag
  (Xavier Leroy)
- #6505: Missed Type-error leads to a segfault upon record access
  (Jacques Garrigue, Jeremy Yallop, report by Christoph Höger)
- #6507: crash on AArch64 resulting from incorrect setting of
  [caml_bottom_of_stack].  (Richard Jones, Mark Shinwell)
- #6509: add -linkall flag to ocamlcommon.cma
  (Frédéric Bour)
- #6513: Fatal error Ctype.Unify(_) in functor type
- #6523: failure upon character bigarray access, and unnecessary change
  in comparison ordering (Jeremy Yallop, Mark Shinwell)
- bound-checking bug in caml_string_{get,set}{16,32,64}
  (Pierre Chambart and Gabriel Scherer, report by Nicolas Trangez)
- sometimes wrong stack alignment at out-of-bounds array access
  (Gabriel Scherer and Xavier Leroy, report by Pierre Chambart)

Features wishes:
- #4243: make the Makefiles parallelizable
  (Grégoire Henry and Damien Doligez)
- #4323: have "of_string" in Num and Big_int work with binary and
           hex representations
  (Zoe Paraskevopoulou, review by Gabriel Scherer)
- #4771: Clarify documentation of Dynlink.allow_only
  (Damien Doligez, report by David Allsopp)
- #4855: 'camlp4 -I +dir' accepted, dir is relative to 'camlp4 -where'
  (Jun Furuse and Hongbo Zhang, report by Dmitry Grebeniuk)
- #5201: ocamlbuild: add --norc to the bash invocation to help performances
  (Daniel Weil)
- #5650: Camlp4FoldGenerator doesn't handle well "abstract" types
  (Hongbo Zhang)
- #5808: allow simple patterns, not just identifiers, in "let p : t = ..."
  (Alain Frisch)
- #5851: warn when -r is disabled because no _tags file is present
  (Gabriel Scherer)
- #5899: a programmer-friendly access to backtrace information
  (Jacques-Henri Jourdan and Gabriel Scherer)
- #6000 comment 9644: add a warning for non-principal coercions to format
  (Jacques Garrigue, report by Damien Doligez)
- #6054: add support for M.[ foo ], M.[| foo |] etc.
  (Kaustuv Chaudhuri)
- #6064: GADT representation for Bigarray.kind + CAML_BA_CHAR runtime kind
  (Jeremy Yallop, review by Gabriel Scherer)
- #6071: Add a -noinit option to the toplevel
  (David Sheets)
- #6087: ocamlbuild, improve _tags parsing of escaped newlines
  (Gabriel Scherer, request by Daniel Bünzli)
- #6109: Typos in ocamlbuild error messages
  (Gabriel Kerneis)
- #6116: more efficient implementation of Digest.to_hex
  (ygrek)
- #6142: add cmt file support to ocamlobjinfo
  (Anil Madhavapeddy)
- #6166: document -ocamldoc option of ocamlbuild
  (Xavier Clerc)
- #6182: better message for virtual objects and class types
  (Leo White, Stephen Dolan)
- #6183: enhanced documentation for 'Unix.shutdown_connection'
  (Anil Madhavapeddy, report by Jun Furuse)
- #6187: ocamlbuild: warn when using -plugin-tag(s) without myocamlbuild.ml
  (Kate Deplaix)
- #6246: allow wildcard _ as for-loop index
  (Alain Frisch, request by ygrek)
- #6267: more information printed by "bt" command of ocamldebug
  (Josh Watzman)
- #6270: remove need for -I directives to ocamldebug in common case
  (Josh Watzman, review by Xavier Clerc and Alain Frisch)
- #6311: Improve signature mismatch error messages
  (Alain Frisch, suggestion by Daniel Bünzli)
- #6358: obey DESTDIR in install targets
  (Gabriel Scherer, request by François Berenger)
- #6388, #6424: more parsetree correctness checks for -ppx users
  (Alain Frisch, request by whitequark and Jun Furuse)
- #6406: Expose OCaml version in C headers
  (whitequark and Romain Calascibetta)
- #6446: improve "unused declaration" warnings wrt. name shadowing
  (Alain Frisch)
- #6495: ocamlbuild tags 'safe_string', 'unsafe_string'
  (Anil Madhavapeddy)
- #6497: pass context information to -ppx preprocessors
  (whitequark, Alain Frisch)
- ocamllex: user-definable refill action
  (Frédéric Bour, review by Gabriel Scherer and Luc Maranget)
- shorten syntax for functor signatures: "functor (M1:S1) (M2:S2) .. -> .."
  (Thomas Gazagnaire and Jeremy Yallop, review by Gabriel Scherer)
- make ocamldebug -I auto-detection work with ocamlbuild
  (Josh Watzman)

OCaml 4.01.0 (12 Sep 2013):
---------------------------

(Changes that can break existing programs are marked with a "*")

Other libraries:
- Labltk: updated to Tcl/Tk 8.6.

Type system:
- #5759: use well-disciplined type information propagation to
  disambiguate label and constructor names
  (Jacques Garrigue, Alain Frisch and Leo White)
* Propagate type information towards pattern-matching, even in the presence of
  polymorphic variants (discarding only information about possibly-present
  constructors). As a result, matching against absent constructors is no longer
  allowed for exact and fixed polymorphic variant types.
  (Jacques Garrigue)
* #6035: Reject multiple declarations of the same method or instance variable
  in an object
  (Alain Frisch)

Compilers:
- #5861: raise an error when multiple private keywords are used in type
  declarations
  (Hongbo Zhang)
- #5634: parsetree rewriter (-ppx flag)
  (Alain Frisch)
- ocamldep now supports -absname
  (Alain Frisch)
- #5768: On "unbound identifier" errors, use spell-checking to suggest names
  present in the environment
  (Gabriel Scherer)
- ocamlc has a new option -dsource to visualize the parsetree
  (Alain Frisch, Hongbo Zhang)
- tools/eqparsetree compares two parsetree ignoring location
  (Hongbo Zhang)
- ocamlopt now uses clang as assembler on OS X if available, which enables
  CFI support for OS X.
  (Benedikt Meurer)
- Added a new -short-paths option, which attempts to use the shortest
  representation for type constructors inside types, taking open modules
  into account. This can make types much more readable if your code
  uses lots of functors.
  (Jacques Garrigue)
- #5986: added flag -compat-32 to ocamlc, ensuring that the generated
  bytecode executable can be loaded on 32-bit hosts.
  (Xavier Leroy)
- #5980: warning on open statements which shadow an existing
  identifier (if it is actually used in the scope of the open); new
  open! syntax to silence it locally
  (Alain Frisch, thanks to a report of Daniel Bünzli)
* warning 3 is extended to warn about other deprecated features:
  - ISO-latin1 characters in identifiers
  - uses of the (&) and (or) operators instead of (&&) and (||)
  (Damien Doligez)
- Experimental OCAMLPARAM for ocamlc and ocamlopt
  (Fabrice Le Fessant)
- #5571: incorrect ordinal number in error message
  (Alain Frisch, report by John Carr)
- #6073: add signature to Tstr_include
  (patch by Leo White)

Standard library:
- #5899: expose a way to inspect the current call stack,
  Printexc.get_callstack
  (Gabriel Scherer, Jacques-Henri Jourdan, Alain Frisch)
- #5986: new flag Marshal.Compat_32 for the serialization functions
  (Marshal.to_*), forcing the output to be readable on 32-bit hosts.
  (Xavier Leroy)
- infix application operators |> and @@ in Pervasives
  (Fabrice Le Fessant)
- #6176: new Format.asprintf function with a %a formatter
  compatible with Format.fprintf (unlike Format.sprintf)
  (Pierre Weis)

Other libraries:
- #5568: add O_CLOEXEC flag to Unix.openfile, so that the returned
  file descriptor is created in close-on-exec mode
  (Xavier Leroy)

Runtime system:
* #6019: more efficient implementation of caml_modify() and caml_initialize().
  The new implementations are less lenient than the old ones: now,
  the destination pointer of caml_modify() must point within the minor or
  major heaps, and the destination pointer of caml_initialize() must
  point within the major heap.
  (Xavier Leroy, from an experiment by Brian Nigito, with feedback
  from Yaron Minsky and Gerd Stolpmann)

Internals:
- Moved debugger/envaux.ml to typing/envaux.ml to publish env_of_only_summary
  as part of compilerlibs, to be used on bin-annot files.
  (Fabrice Le Fessant)
- The test suite can now be run without installing OCaml first.
  (Damien Doligez)

Bug fixes:
- #3236: Document the fact that queues are not thread-safe
  (Damien Doligez)
- #3468: (part 1) Sys_error documentation
  (Damien Doligez)
- #3679: Warning display problems
  (Fabrice Le Fessant)
- #3963: Graphics.wait_next_event in Win32 hangs if window closed
  (Damien Doligez)
- #4079: Queue.copy is now tail-recursive
  (patch by Christophe Papazian)
- #4138: Documentation for Unix.mkdir
  (Damien Doligez)
- #4469: emacs mode: caml-set-compile-command is annoying with ocamlbuild
  (Daniel Bünzli)
- #4485: Graphics: Keyboard events incorrectly delivered in native code
  (Damien Doligez, report by Sharvil Nanavati)
- #4502: ocamlbuild now reliably excludes the build-dir from hygiene check
  (Gabriel Scherer, report by Romain Bardou)
- #4762: ?? is not used at all, but registered as a lexer token
  (Alain Frisch)
- #4788: wrong error message when executable file is not found for backtrace
  (Damien Doligez, report by Claudio Sacerdoti Coen)
- #4812: otherlibs/unix: add extern int code_of_unix_error (value error);
  (Goswin von Brederlow)
- #4887: input_char after close_in crashes ocaml (msvc runtime)
  (Alain Frisch and Christoph Bauer, report by ygrek)
- #4994: ocaml-mode doesn't work with xemacs21
  (Damien Doligez, report by Stéphane Glondu)
- #5098: creating module values may lead to memory leaks
  (Alain Frisch, report by Milan Stanojević)
- #5102: ocamlbuild fails when using an unbound variable in rule dependency
  (Xavier Clerc, report by Daniel Bünzli)
* #5119: camlp4 now raises a specific exception when 'DELETE_RULE' fails,
  rather than raising 'Not_found'
  (ygrek)
- #5121: %( %) in Format module seems to be broken
  (Pierre Weis, first patch by Valentin Gatien-Baron, report by Khoo Yit Phang)
- #5178: document in INSTALL how to build a 32-bit version under Linux x86-64
  (Benjamin Monate)
- #5212: Improve ocamlbuild error messages of _tags parser
  (ygrek)
- #5240: register exception printers for Unix.Unix_error and Dynlink.Error
  (Jérémie Dimino)
- #5300: ocamlbuild: verbose parameter should implicitly set classic display
  (Xavier Clerc, report by Robert Jakob)
- #5327: (Windows) Unix.select blocks if same socket listed in first and
  third arguments
  (David Allsopp, displaying impressive MSDN skills)
- #5343: ocaml -rectypes is unsound wrt module subtyping (was still unsound)
  (Jacques Garrigue)
- #5350: missing return code checks in the runtime system
  (Xavier Leroy)
- #5468: ocamlbuild should preserve order of parametric tags
  (Wojciech Meyer, report by Dario Teixeira)
- #5551: Avoid repeated lookups for missing cmi files
  (Alain Frisch)
- #5552: unrecognized gcc option -no-cpp-precomp
  (Damien Doligez, report by Markus Mottl)
* #5580: missed opportunities for constant propagation
  (Xavier Leroy and John Carr)
- #5611: avoid clashes between .cmo files and output files during linking
  (Wojciech Meyer)
- #5662: typo in md5.c
  (Olivier Andrieu)
- #5673: type equality in a polymorphic field
  (Jacques Garrigue, report by Jean-Louis Giavitto)
- #5674: Methods call are 2 times slower with 4.00 than with 3.12
  (Jacques Garrigue, Gabriel Scherer, report by Jean-Louis Giavitto)
- #5694: Exception raised by type checker
  (Jacques Garrigue, report by Markus Mottl)
- #5695: remove warnings on sparc code emitter
  (Fabrice Le Fessant)
- #5697: better location for warnings on statement expressions
  (Dan Bensen)
- #5698: remove hardcoded limit of 200000 labels in emitaux.ml
  (Fabrice Le Fessant, report by Marcin Sawicki)
- #5702: bytecomp/bytelibrarian lib_sharedobjs was defined but never used
  (Hongbo Zhang, Fabrice Le Fessant)
- #5708: catch Failure"int_of_string" in ocamldebug
  (Fabrice Le Fessant, report by user 'schommer')
- #5712: (9) new option -bin-annot is not documented
  (Damien Doligez, report by Hendrik Tews)
- #5731: instruction scheduling forgot to account for destroyed registers
  (Xavier Leroy, Benedikt Meurer, reported by Jeffrey Scofield)
- #5734: improved Win32 implementation of Unix.gettimeofday
  (David Allsopp)
- #5735: %apply and %revapply not first class citizens
  (Fabrice Le Fessant, reported by Jun Furuse)
- #5738: first class module patterns not handled by ocamldep
  (Fabrice Le Fessant, Jacques Garrigue, reported by Hongbo Zhang)
- #5739: Printf.printf "%F" (-.nan) returns -nan
  (Xavier Leroy, David Allsopp, reported by Samuel Mimram)
- #5741: make pprintast.ml in compiler_libs
  (Alain Frisch, Hongbo Zhang)
- #5747: 'unused open' warning not given when compiling with -annot
  (Alain Frisch, reported by Valentin Gatien-Baron)
- #5752: missing dependencies at byte-code link with mlpack
  (Wojciech Meyer, Nicholas Lucaroni)
- #5763: ocamlbuild does not give correct flags when running menhir
  (Gabriel Scherer, reported by Philippe Veber)
- #5765: ocamllex doesn't preserve line directives
  (Damien Doligez, reported by Martin Jambon)
- #5770: Syntax error messages involving unclosed parens are sometimes
  incorrect
  (Michel Mauny)
- #5772: problem with marshaling of mutually-recursive functions
  (Jacques-Henri Jourdan, reported by Cédric Pasteur)
- #5775: several bug fixes for tools/pprintast.ml
  (Hongbo Zhang)
- #5784: -dclambda option is ignored
  (Pierre Chambart)
- #5785: misbehaviour with abstracted structural type used as GADT index
  (Jacques Garrigue, report by Jeremy Yallop)
- #5787: Bad behavior of 'Unused ...' warnings in the toplevel
  (Alain Frisch)
- #5793: integer marshalling is inconsistent between architectures
  (Xavier Clerc, report by Pierre-Marie Pédrot)
- #5798: add ARM VFPv2 support for Raspbian (ocamlopt)
  (Jeffrey Scofield and Anil Madhavapeddy, patch review by Benedikt Meurer)
- #5802: Avoiding "let" as a value name
  (Jacques Garrigue, report by Tiphaine Turpin)
- #5805: Assert failure with warning 34 on pre-processed file
  (Alain Frisch, report by Tiphaine Turpin)
- #5806: ensure that backtrace tests are always run (testsuite)
  (Xavier Clerc, report by user 'michi')
- #5809: Generating .cmt files takes a long time, in case of type error
  (Alain Frisch)
- #5810: error in switch printing when using -dclambda
  (Pierre Chambart)
- #5811: Untypeast produces singleton tuples for constructor patterns
  with only one argument
  (Tiphaine Turpin)
- #5813: GC not called when unmarshaling repeatedly in a tight loop (ocamlopt)
  (Xavier Leroy, report by David Waern)
- #5814: read_cmt -annot does not report internal references
  (Alain Frisch)
- #5815: Multiple exceptions in signatures gives an error
  (Leo White)
- #5816: read_cmt -annot does not work for partial .cmt files
  (Alain Frisch)
- #5819: segfault when using [with] on large recursive record (ocamlopt)
  (Xavier Leroy, Damien Doligez)
- #5821: Wrong record field is reported as duplicate
  (Alain Frisch, report by Martin Jambon)
- #5824: Generate more efficient code for immediate right shifts.
  (Pierre Chambart, review by Xavier Leroy)
- #5825: Add a toplevel primitive to use source file wrapped with the
  corresponding module
  (Grégoire Henry, Wojciech Meyer, caml-list discussion)
- #5833: README.win32 can leave the wrong flexlink in the path
  (Damien Doligez, report by William Smith)
- #5835: nonoptional labeled arguments can be passed with '?'
  (Jacques Garrigue, report by Elnatan Reisner)
- #5840: improved documentation for 'Unix.lseek'
  (Xavier Clerc, report by Matej Košík)
- #5848: Assertion failure in type checker
  (Jacques Garrigue, Alain Frisch, report by David Waern)
- #5858: Assert failure during typing of class
  (Jacques Garrigue, report by Julien Signoles)
- #5865: assert failure when reporting undefined field label
  (Jacques Garrigue, report by Anil Madhavapeddy)
- #5872: Performance: Buffer.add_char is not inlined
  (Gerd Stolpmann, Damien Doligez)
- #5876: Uncaught exception with a typing error
  (Alain Frisch, Gabriel Scherer, report by Julien Moutinho)
- #5877: multiple "open" can become expensive in memory
  (Fabrice Le Fessant and Alain Frisch)
- #5880: 'Genlex.make_lexer' documentation mentions the wrong exception
  (Xavier Clerc, report by Virgile Prevosto)
- #5885: Incorrect rule for compiling C stubs when shared libraries are not
  supported.
  (Jérôme Vouillon)
- #5891: ocamlbuild: support rectypes tag for mlpack
  (Khoo Yit Phang)
- #5892: GADT exhaustiveness check is broken
  (Jacques Garrigue and Leo White)
- #5906: GADT exhaustiveness check is still broken
  (Jacques Garrigue, report by Sébastien Briais)
- #5907: Undetected cycle during typecheck causes exceptions
  (Jacques Garrigue, report by Pascal Zimmer)
- #5910: Fix code generation bug for "mod 1" on ARM.
  (Benedikt Meurer, report by user 'jteg68')
- #5911: Signature substitutions fail in submodules
  (Jacques Garrigue, report by Markus Mottl)
- #5912: add configure option -no-cfi (for OSX 10.6.x with XCode 4.0.2)
  (Damien Doligez against XCode versions, report by Thomas Gazagnaire)
- #5914: Functor breaks with an equivalent argument signature
  (Jacques Garrigue, report by Markus Mottl and Grégoire Henry)
- #5920, #5957: linking failure for big bytecodes on 32bit architectures
  (Benoît Vaugon and Chet Murthy, report by Jun Furuse and Sebastien Mondet)
- #5928: Missing space between words in manual page for ocamlmktop
  (Damien Doligez, report by Matej Košík)
- #5930: ocamldep leaks temporary preprocessing files
  (Gabriel Scherer, report by Valentin Gatien-Baron)
- #5933: Linking is slow when there are functions with large arities
  (Valentin Gatien-Baron, review by Gabriel Scherer)
- #5934: integer shift by negative amount (in otherlibs/num)
  (Xavier Leroy, report by John Regehr)
- #5944: Bad typing performances of big variant type declaration
  (Benoît Vaugon)
- #5945: Mix-up of Minor_heap_min and Minor_heap_max units
  (Benoît Vaugon)
- #5948: GADT with polymorphic variants bug
  (Jacques Garrigue, report by Leo White)
- #5953: Unix.system does not handle EINTR
  (Jérémie Dimino)
- #5965: disallow auto-reference to a recursive module in its definition
  (Alain Frisch, report by Arthur Windler via Gabriel Scherer)
- #5973: Format module incorrectly parses format string
  (Pierre Weis, report by Frédéric Bour)
- #5974: better documentation for Str.regexp
  (Damien Doligez, report by william)
- #5976: crash after recovering from two stack overflows (ocamlopt on MacOS X)
  (Xavier Leroy, report by Pierre Boutillier)
- #5977: Build failure on raspberry pi: "input_value: integer too large"
  (Alain Frisch, report by Sylvain Le Gall)
- #5981: Incompatibility check assumes abstracted types are injective
  (Jacques Garrigue, report by Jeremy Yallop)
- #5982: caml_leave_blocking section and errno corruption
  (Jérémie Dimino)
- #5985: Unexpected interaction between variance and GADTs
  (Jacques Garrigue, Jeremy Yallop and Leo White and Gabriel Scherer)
- #5988: missing from the documentation: -impl is a valid flag for ocamlopt
  (Damien Doligez, report by Vincent Bernardoff)
- #5989: Assumed inequalities involving private rows
  (Jacques Garrigue, report by Jeremy Yallop)
- #5992: Crash when pattern-matching lazy values modifies the scrutinee
  (Luc Maranget, Leo White)
- #5993: Variance of private type abbreviations not checked for modules
  (Jacques Garrigue)
- #5997: Non-compatibility assumed for concrete types with same constructor
  (Jacques Garrigue, report by Gabriel Scherer)
- #6004: Type information does not flow to "inherit" parameters
  (Jacques Garrigue, report by Alain Frisch)
- #6005: Type unsoundness with recursive modules
  (Jacques Garrigue, report by Jérémie Dimino and Josh Berdine)
- #6010: Big_int.extract_big_int gives wrong results on negative arguments
  (Xavier Leroy, report by Drake Wilson via Stéphane Glondu)
- #6024: Format syntax for printing @ is incompatible with 3.12.1
  (Damien Doligez, report by Boris Yakobowski)
- #6001: Reduce the memory used by compiling Camlp4
  (Hongbo Zhang and Gabriel Scherer, report by Henri Gouraud)
- #6031: Camomile problem with -with-frame-pointers
  (Fabrice Le Fessant, report by Anil Madhavapeddy)
- #6032: better Random.self_init under Windows
  (Alain Frisch, Xavier Leroy)
- #6033: Matching.inline_lazy_force needs eta-expansion (command-line flags)
  (Pierre Chambart, Xavier Leroy and Luc Maranget,
   regression report by Gabriel Scherer)
- #6046: testsuite picks up the wrong ocamlrun dlls
  (Anil Madhavapeddy)
- #6056: Using 'match' prevents generalization of values
  (Jacques Garrigue, report by Elnatan Reisner)
- #6058: 'ocamlbuild -use-ocamlfind -tag thread -package threads t.cma' fails
  (Gabriel Scherer, report by Hezekiah M. Carty)
- #6069: ocamldoc: lexing: empty token
  (Maxence Guesdon, Grégoire Henry, report by ygrek)
- #6072: configure does not handle FreeBSD current (i.e. 10) correctly
  (Damien Doligez, report by Prashanth Mundkur)
- #6074: Wrong error message for failing Condition.broadcast
  (Markus Mottl)
- #6084: Define caml_modify and caml_initialize as weak symbols to help
  with Netmulticore
  (Xavier Leroy, Gerd Stolpmann)
- #6090: Module constraint + private type seems broken in ocaml 4.01.0
  (Jacques Garrigue, report by Kate Deplaix)
- #6109: Typos in ocamlbuild error messages
  (Gabriel Kerneis)
- #6123: Assert failure when self escapes its class
  (Jacques Garrigue, report by whitequark)
- #6158: Fatal error using GADTs
  (Jacques Garrigue, report by Jeremy Yallop)
- #6163: Assert_failure using polymorphic variants in GADTs
  (Jacques Garrigue, report by Leo White)
- #6164: segmentation fault on Num.power_num of 0/1
  (Fabrice Le Fessant, report by Johannes Kanig)
- #6210: Camlp4 location error
  (Hongbo Zhang, report by Jun Furuse)

Feature wishes:
- #5181: Merge common floating point constants in ocamlopt
  (Benedikt Meurer)
- #5243: improve the ocamlbuild API documentation in signatures.mli
  (Christophe Troestler)
- #5546: moving a function into an internal module slows down its use
  (Alain Frisch, report by Fabrice Le Fessant)
- #5597: add instruction trace option 't' to OCAMLRUNPARAM
  (Anil Madhavapeddy, Wojciech Meyer)
- #5676: IPv6 support under Windows
  (Jérôme Vouillon, review by Jonathan Protzenko)
- #5721: configure -with-frame-pointers for Linux perf profiling
  (Fabrice Le Fessant, test by Jérémie Dimino)
- #5722: toplevel: print full module path only for first record field
  (Jacques Garrigue, report by ygrek)
- #5762: Add primitives for fast access to bigarray dimensions
  (Pierre Chambart)
- #5769: Allow propagation of Sys.big_endian in native code
  (Pierre Chambart, stealth commit by Fabrice Le Fessant)
- #5771: Add primitives for reading 2, 4, 8 bytes in strings and bigarrays
  (Pierre Chambart)
- #5774: Add bswap primitives for amd64 and arm
  (Pierre Chambart, test by Alain Frisch)
- #5795: Generate sqrtsd opcode instead of external call to sqrt on amd64
  (Pierre Chambart)
- #5827: provide a dynamic command line parsing mechanism
  (Hongbo Zhang)
- #5832: patch to improve "wrong file naming" error messages
  (William Smith)
- #5864: Add a find operation to Set
  (François Berenger)
- #5886: Small changes to compile for Android
  (Jérôme Vouillon, review by Benedikt Meurer)
- #5902: -ppx based pre-processor executables accept arguments
  (Alain Frisch, report by Wojciech Meyer)
- #5986: Protect against marshaling 64-bit integers in bytecode
  (Xavier Leroy, report by Alain Frisch)
- #6049: support for OpenBSD/macppc platform
  (Anil Madhavapeddy, review by Benedikt Meurer)
- #6059: add -output-obj rules for ocamlbuild
  (Anil Madhavapeddy)
- #6060: ocamlbuild tags 'principal', 'strict_sequence' and 'short_paths'
  (Anil Madhavapeddy)
- ocamlbuild tag 'no_alias_deps'
  (Daniel Bünzli)

Tools:
- OCamlbuild now features a bin_annot tag to generate .cmt files.
  (Jonathan Protzenko)
- OCamlbuild now features a strict_sequence tag to trigger the
  strict-sequence option.
  (Jonathan Protzenko)
- OCamlbuild now picks the non-core tools like ocamlfind and menhir from PATH
  (Wojciech Meyer)
- #5884: Misc minor fixes and cleanup for emacs mode
  (Stefan Monnier)
- #6030: Improve performance of -annot
  (Guillaume Melquiond, Alain Frisch)

OCaml 4.00.1 (5 Oct 2012):
--------------------------

Bug fixes:
- #4019: better documentation of Str.matched_string
- #5111: ocamldoc, heading tags inside spans tags is illegal in html
- #5278: better error message when typing "make"
- #5468: ocamlbuild should preserve order of parametric tags
- #5563: harden Unix.select against file descriptors above FD_SETSIZE
- #5690: "ocamldoc ... -text README" raises exception
- #5700: crash with native-code stack backtraces under MacOS 10.8 x86-64
- #5707: AMD64 code generator: do not use r10 and r11 for parameter passing,
  as these registers can be destroyed by the dynamic loader
- #5712: some documentation problems
- #5715: configuring with -no-shared-libs breaks under cygwin
- #5718: false positive on 'unused constructor' warning
- #5719: ocamlyacc generates code that is not warning 33-compliant
- #5725: ocamldoc output of preformatted code
- #5727: emacs caml-mode indents shebang line in toplevel scripts
- #5729: tools/untypeast.ml creates unary Pexp_tuple
- #5731: instruction scheduling forgot to account for destroyed registers
- #5735: %apply and %revapply not first class citizens
- #5738: first class module patterns not handled by ocamldep
- #5742: missing bound checks in Array.sub
- #5744: ocamldoc error on "val virtual"
- #5757: GC compaction bug (crash)
- #5758: Compiler bug when matching on floats
- #5761: Incorrect bigarray custom block size


OCaml 4.00.0 (26 Jul 2012):
---------------------------

(Changes that can break existing programs are marked with a "*")

- The official name of the language is now OCaml.

Language features:
- Added Generalized Algebraic Data Types (GADTs) to the language.
  See chapter "Language extensions" of the reference manual for documentation.
- It is now possible to omit type annotations when packing and unpacking
  first-class modules. The type-checker attempts to infer it from the context.
  Using the -principal option guarantees forward compatibility.
- New (module M) and (module M : S) syntax in patterns, for immediate
  unpacking of a first-class module.

Compilers:
- Revised simplification of let-alias (#5205, #5288)
- Better reporting of compiler version mismatch in .cmi files
* Warning 28 is now enabled by default.
- New option -absname to use absolute paths in error messages
- Optimize away compile-time beta-redexes, e.g. (fun x y -> e) a b.
- Added option -bin-annot to dump the AST with type annotations.
- Added lots of new warnings about unused variables, opens, fields,
  constructors, etc.
* New meaning for warning 7: it is now triggered when a method is overridden
  with the "method" keyword.  Use "method!" to avoid the warning.

Native-code compiler:
- Optimized handling of partially-applied functions (#5287)
- Small improvements in code generated for array bounds checks (#5345,
  #5360).
* New ARM backend (#5433):
    . Supports both Linux/EABI (armel) and Linux/EABI+VFPv3 (armhf).
    . Added support for the Thumb-2 instruction set with average code size
      savings of 28%.
    . Added support for position-independent code, natdynlink, profiling and
      exception backtraces.
- Generation of CFI information, and filename/line number debugging (with -g)
  annotations, enabling in particular precise stack backtraces with
  the gdb debugger. Currently supported for x86 32-bits and 64-bits only.
  (#5487)
- New tool: ocamloptp, the equivalent of ocamlcp for the native-code compiler.

OCamldoc:
- #5645: ocamldoc doesn't handle module/type substitution in signatures
- #5544: improve HTML output (less formatting in html code)
- #5522: allow referring to record fields and variant constructors
- fix #5419 (error message in french)
- fix #5535 (no cross ref to class after dump+load)
* Use first class modules for custom generators, to be able to
  load various plugins incrementally adding features to the current
  generator
* #5507: Use Location.t structures for locations.
- fix: do not keep code when not told to keep code.

Standard library:
- Added float functions "hypot" and "copysign" (#3806, #4752, #5246)
* Arg: options with empty doc strings are no longer included in the usage string
  (#5437)
- Array: faster implementations of "blit", "copy", "sub", "append" and "concat"
  (#2395, #2787, #4591)
* Hashtbl:
    . Statistically-better generic hash function based on Murmur 3 (#5225)
    . Fixed behavior of generic hash function w.r.t. -0.0 and NaN (#5222)
    . Added optional "random" parameter to Hashtbl.create to randomize
      collision patterns and improve security (#5572, CVE-2012-0839)
    . Added "randomize" function and "R" parameter to OCAMLRUNPARAM
      to turn randomization on by default (#5572, CVE-2012-0839)
    . Added new functorial interface "MakeSeeded" to support randomization
      with user-provided seeded hash functions.
    . Install new header <caml/hash.h> for C code.
- Filename: on-demand (lazy) initialization of the PRNG used by "temp_file".
- Marshal: marshalling of function values (flag Marshal.Closures) now
  also works for functions that come from dynamically-loaded modules (#5215)
- Random:
     . More random initialization (Random.self_init()), using /dev/urandom
       when available (e.g. Linux, FreeBSD, MacOS X, Solaris)
     * Faster implementation of Random.float (changes the generated sequences)
- Format strings for formatted input/output revised to correct #5380
    . Consistently treat %@ as a plain @ character
    . Consistently treat %% as a plain % character
- Scanf: width and precision for floating point numbers are now handled
- Scanf: new function "unescaped" (#3888)
- Set and Map: more efficient implementation of "filter" and "partition"
- String: new function "map" (#3888)

Installation procedure:
- Compiler internals are now installed in `ocamlc -where`/compiler-libs.
  The files available there include the .cmi interfaces for all compiler
  modules, plus the following libraries:
      ocamlcommon.cma/.cmxa     modules common to ocamlc, ocamlopt, ocaml
      ocamlbytecomp.cma/.cmxa   modules for ocamlc and ocaml
      ocamloptcomp.cma/.cmxa    modules specific to ocamlopt
      ocamltoplevel.cma         modules specific to ocaml
   (#8255, #4653, frequently-asked feature).
* Some .cmi for toplevel internals that used to be installed in
  `ocamlc -where` are now to be found in  `ocamlc -where`/compiler-libs.
  Add "-I +compiler-libs" where needed.
* toplevellib.cma is no longer installed because subsumed by
  ocamlcommon.cma ocamlbytecomp.cma ocamltoplevel.cma
- Added a configuration option (-with-debug-runtime) to compile and install
  a debug version of the runtime system, and a compiler option
  (-runtime-variant) to select the debug runtime.

Bug Fixes:

- #8109: functions of the Lazy module whose named started with 'lazy_' have
  been deprecated, and new ones without the prefix added
- #3571: in Bigarrays, call msync() before unmapping to commit changes
- #4292: various documentation problems
- #4511, #4838: local modules remove polymorphism
* #4549: Filename.dirname is not handling multiple / on Unix
- #4688: (Windows) special floating-point values aren't converted to strings
  correctly
- #4697: Unix.putenv leaks memory on failure
- #4705: camlp4 does not allow to define types with `True or `False
- #4746: wrong detection of stack overflows in native code under Linux
- #4869: rare collisions between assembly labels for code and data
- #4880: "assert" constructs now show up in the exception stack backtrace
- #4892: Array.set could raise "out of bounds" before evaluating 3rd arg
- #4937: camlp4 incorrectly handles optional arguments if 'option' is
  redefined
- #5024: camlp4r now handles underscores in irrefutable pattern matching of
  records
- #5064, #5485: try to ensure that 4K words of stack are available
  before calling into C functions, raising a Stack_overflow exception
  otherwise.  This reduces (but does not eliminate) the risk of
  segmentation faults due to stack overflow in C code
- #5073: wrong location for 'Unbound record field label' error
- #5084: sub-sub-module building fails for native code compilation
- #5120: fix the output function of Camlp4.Debug.formatter
- #5131: compilation of custom runtime with g++ generates lots of warnings
- #5137: caml-types-explore does not work
- #5159: better documentation of type Lexing.position
- #5171: Map.join does more comparisons than needed
- #5176: emacs mode: stack overflow in regexp matcher
- #5179: port OCaml to mingw-w64
- #5211: updated Genlex documentation to state that camlp4 is mandatory for
  'parser' keyword and associated notation
- #5214: ocamlfind plugin invokes 'cut' utility
- #5218: use $(MAKE) instead of "make" in Makefiles
- #5224: confusing error message in non-regular type definition
- #5231: camlp4: fix parsing of <:str_item< type t = $x$ >>
- #5233: finaliser on weak array gives dangling pointers (crash)
- #5238, #5277: Sys_error when getting error location
- #5261, #5497: Ocaml source-code examples are not "copy-paste-able"
* #5279: executable name is not initialized properly in caml_startup_code
- #5290: added hash functions for channels, nats, mutexes, conditions
- #5291: undetected loop in class initialization
- #5295: OS threads: problem with caml_c_thread_unregister()
- #5301: camlp4r and exception equal to another one with parameters
- #5305: prevent ocamlbuild from complaining about links to _build/
- #5306: comparing to Thread.self() raises exception at runtime
- #5309: Queue.add is not thread/signal safe
- #5310: Ratio.create_ratio/create_normalized_ratio have misleading names
- #5311: better message for warning 23
* #5312: command-line arguments @reponsefile auto-expansion feature
  removed from the Windows OCaml runtime, to avoid conflicts with "-w @..."
- #5313: ocamlopt -g misses optimizations
- #5214: ocamlfind plugin invokes 'cut' utility
- #5316: objinfo now shows ccopts/ccobjs/force_link when applicable
- #5318: segfault on stack overflow when reading marshaled data
- #5319: %r11 clobbered by Lswitch in Windows AMD64 native-code compilation
- #5322: type abbreviations expanding to a universal type variable
- #5328: under Windows, Unix.select leaves sockets in non-blocking mode
- #5330: thread tag with '.top' and '.inferred.mli' targets
- #5331: ocamlmktop is not always a shell script
- #5335: Unix.environment segfaults after a call to clearenv
- #5338: sanitize.sh has windows style end-of-lines (mingw)
- #5344: some predefined exceptions need special printing
- #5349: Hashtbl.replace uses new key instead of reusing old key
- #5356: ocamlbuild handling of 'predicates' for ocamlfind
- #5364: wrong compilation of "((val m : SIG1) : SIG2)"
- #5370: ocamldep omits filename in syntax error message
- #5374: camlp4 creates wrong location for type definitions
- #5380: strange sscanf input segfault
- #5382: EOPNOTSUPP and ENOTSUPP different on exotic platforms
- #5383: build failure in Win32/MSVC
- #5387: camlp4: str_item and other syntactic elements with Nils are
  not very usable
- #5389: compaction sometimes leaves a very large heap
- #5393: fails to build from source on GNU/kFreeBSD because of -R link option
- #5394: documentation for -dtypes is missing in manpage
- #5397: Filename.temp_dir_name should be mutable
- #5410: fix printing of class application with Camlp4
- #5416: (Windows) Unix.(set|clear)_close_on_exec now preserves blocking mode
- #5435: ocamlbuild does not find .opt executables on Windows
- #5436: update object ids on unmarshaling
- #5442: camlp4: quotation issue with strings
- #5453: configure doesn't find X11 under Ubuntu/MultiarchSpec
- #5461: Double linking of bytecode modules
- #5463: Bigarray.*.map_file fail if empty array is requested
- #5465: increase stack size of ocamlopt.opt for windows
- #5469: private record type generated by functor loses abbreviation
- #5475: Wrapper script for interpreted LablTk wrongly handles command line
  parameters
- #5476: bug in native code compilation of let rec on float arrays
- #5477: use pkg-config to configure graphics on linux
- #5481: update camlp4 magic numbers
- #5482: remove bashism in test suite scripts
- #5495: camlp4o dies on infix definition (or)
- #5498: Unification with an empty object only checks the absence of
  the first method
- #5503: error when ocamlbuild is passed an absolute path as build directory
- #5509: misclassification of statically-allocated empty array that
  falls exactly at beginning of an otherwise unused data page.
- #5510: ocamldep has duplicate -ml{,i}-synonym options
- #5511: in Bigarray.reshape, unwarranted limitation on new array dimensions.
- #5513: Int64.div causes floating point exception (ocamlopt, x86)
- #5516: in Bigarray C stubs, use C99 flexible array types if possible
- #5518: segfault with lazy empty array
- #5531: Allow ocamlbuild to add ocamldoc flags through -docflag
  and -docflags switches
- #5538: combining -i and -annot in ocamlc
- #5543: in Bigarray.map_file, try to avoid using lseek() when growing file
- #5648: (probably fixed) test failures in tests/lib-threads
- #5551: repeated calls to find_in_path degrade performance
- #5552: Mac OS X: unrecognized gcc option "-no-cpp-precomp"
- #5555: add Hashtbl.reset to resize the bucket table to its initial size
- #5560: incompatible type for tuple pattern with -principal
- #5575: Random states are not marshallable across architectures
- #5579: camlp4: when a plugin is loaded in the toplevel,
  Token.Filter.define_filter has no effect before the first syntax error
- #5585: typo: "explicitely"
- #5587: documentation: "allows to" is not correct English
- #5593: remove C file when -output-obj fails
- #5597: register names for instrtrace primitives in embedded bytecode
- #5598: add backslash-space support in strings in ocamllex
- #5603: wrong .file debug info generated by ocamlopt -g
- #5604: fix permissions of files created by ocamlbuild itself
- #5610: new unmarshaler (from #5318) fails to freshen object identifiers
- #5614: add missing -linkall flag when compiling ocamldoc.opt
- #5616: move ocamlbuild documentation to the reference manual
- #5619: Uncaught CType.Unify exception in the compiler
- #5620: invalid printing of type manifest (camlp4 revised syntax)
- #5637: invalid printing of anonymous type parameters (camlp4 revised syntax)
- #5643: issues with .cfi and .loc directives generated by ocamlopt -g
- #5644: Stream.count broken when used with Sapp or Slazy nodes
- #5647: Cannot use install_printer in debugger
- #5651: printer for abstract data type (camlp4 revised syntax)
- #5654: self pattern variable location tweak
- #5655: ocamlbuild doesn't pass cflags when building C stubs
- #5657: wrong error location for abbreviated record fields
- #5659: ocamlmklib -L option breaks with MSVC
- #5661: fixes for the test suite
- #5668: Camlp4 produces invalid syntax for "let _ = ..."
- #5671: initialization of compare_ext field in caml_final_custom_operations()
- #5677: do not use "value" as identifier (genprintval.ml)
- #5687: dynlink broken when used from "output-obj" main program (bytecode)
- problem with printing of string literals in camlp4 (reported on caml-list)
- emacs mode: colorization of comments and strings now works correctly
- problem with forall and method (reported on caml-list on 2011-07-26)
- crash when using OCAMLRUNPARAM=a=X with invalid X (reported in private)

Feature wishes:
- #2757: new option "-stdin" to make ocaml read stdin as a script
- #3358: better error message when mixing -a and .cmxa
- #3492: documentation: remove restriction on mixed streams
- #7971: allow configuring LIBDIR, BINDIR, and MANDIR relative to $(PREFIX)
- #8285: add Digest.from_hex
- #8341: toplevel: add option to suppress continuation prompts
- #4278: configure: option to disable "graph" library
- #4444: new String.trim function, removing leading and trailing whistespace
- #4549: make Filename.dirname/basename POSIX compliant
- #4830: add option -v to expunge.ml
- #4898: new Sys.big_endian boolean for machine endianness
- #4963, #5467: no extern "C" into ocaml C-stub headers
- #5199: tests are run only for bytecode if either native support is missing,
  or a non-empty value is set to "BYTECODE_ONLY" Makefile variable
- #5215: marshalling of dynlinked closure
- #5236: new '%revapply' primitive with the semantics 'revapply x f = f x',
    and '%apply' with semantics 'apply f x = f x'.
- #5255: natdynlink detection on powerpc, hurd, sparc
- #5295: OS threads: problem with caml_c_thread_unregister()
- #5297: compiler now checks existence of builtin primitives
- #5329: (Windows) more efficient Unix.select if all fd's are sockets
- #5357: warning for useless open statements
- #5358: first class modules don't allow "with type" declarations for types
  in sub-modules
- #5385: configure: emit a warning when MACOSX_DEPLOYMENT_TARGET is set
- #5396: ocamldep: add options -sort, -all, and -one-line
- #5397: Filename.temp_dir_name should be mutable
- #5403: give better error message when emacs is not found in PATH
- #5411: new directive for the toplevel: #load_rec
- #5420: Unix.openfile share mode (Windows)
- #5421: Unix: do not leak fds in various open_proc* functions
- #5434: implement Unix.times in win32unix (partially)
- #5438: new warnings for unused declarations
- #5439: upgrade config.guess and config.sub
- #5445 and others: better printing of types with user-provided names
- #5454: Digest.compare is missing and md5 doc update
- #5455: .emacs instructions, add lines to recognize ocaml scripts
- #5456: pa_macro: replace __LOCATION__ after macro expansion; add LOCATION_OF
- #5461: bytecode: emit warning when linking two modules with the same name
- #5478: ocamlopt assumes ar command exists
- #5479: Num.num_of_string may raise an exception, not reflected in the
  documentation.
- #5501: increase IO_BUFFER_SIZE to 64KiB
- #5532: improve error message when bytecode file is wrong
- #5555: add function Hashtbl.reset to resize the bucket table to
  its initial size.
- #5586: increase UNIX_BUFFER_SIZE to 64KiB
- #5597: register names for instrtrace primitives in embedded bytecode
- #5599: Add warn() tag in ocamlbuild to control -w compiler switch
- #5628: add #remove_directory and Topdirs.remove_directory to remove
  a directory from the load path
- #5636: in system threads library, issue with linking of pthread_atfork
- #5666: C includes don't provide a revision number
- ocamldebug: ability to inspect values that contain code pointers
- ocamldebug: new 'environment' directive to set environment variables
  for debuggee
- configure: add -no-camlp4 option

Shedding weight:
* Removed the obsolete native-code generators for Alpha, HPPA, IA64 and MIPS.
* The "DBM" library (interface with Unix DBM key-value stores) is no
  longer part of this distribution.  It now lives its own life at
  https://forge.ocamlcore.org/projects/camldbm/
* The "OCamlWin" toplevel user interface for MS Windows is no longer
  part of this distribution.  It now lives its own life at
  https://forge.ocamlcore.org/projects/ocamltopwin/

Other changes:
- Copy VERSION file to library directory when installing.


OCaml 3.12.1 (4 Jul 2011):
--------------------------

Bug fixes:
- #4345, #4767: problems with camlp4 printing of float values
- #4380: ocamlbuild should not use tput on windows
- #4487, #5164: multiple 'module type of' are incompatible
- #4552: ocamlbuild does not create symlinks when using '.itarget' file
- #4673, #5144: camlp4 fails on object copy syntax
- #4702: system threads: cleanup tick thread at exit
- #4732: camlp4 rejects polymorphic variants using keywords from macros
- #4778: Win32/MSVC port: rare syntax error in generated MASM assembly file
- #4794, #4959: call annotations not generated by ocamlopt
- #4820: revised syntax pretty printer crashes with 'Stack_overflow'
- #4928: wrong printing of classes and class types by camlp4
- #4939: camlp4 rejects patterns of the '?x:_' form
- #4967: ocamlbuild passes wrong switches to ocamldep through menhir
- #4972: mkcamlp4 does not include 'dynlink.cma'
- #5039: ocamlbuild should use '-linkpkg' only when linking programs
- #5066: ocamldoc: add -charset option used in html generator
- #5069: fcntl() in caml_sys_open may block, do it within blocking section
- #5071, #5129, #5134: inconsistencies between camlp4 and camlp4* binaries
- #5080, #5104: regression in type constructor handling by camlp4
- #5090: bad interaction between toplevel and camlp4
- #5095: ocamlbuild ignores some tags when building bytecode objects
- #5100: ocamlbuild always rebuilds a 'cmxs' file
- #5103: build and install objinfo when building with ocamlbuild
- #5109: crash when a parser calls a lexer that calls another parser
- #5110: invalid module name when using optional argument
- #5115: bytecode executables produced by msvc64 port crash on 32-bit versions
- #5117: bigarray: wrong function name without HAS_MMAP; missing include
- #5118: Camlp4o and integer literals
- #5122: camlp4 rejects lowercase identifiers for module types
- #5123: shift_right_big_int returns a wrong zero
- #5124: substitution inside a signature leads to odd printing
- #5128: typo in 'Camlp4ListComprehension' syntax extension
- #5136: obsolete function used in emacs mode
- #5145: ocamldoc: missing html escapes
- #5146: problem with spaces in multi-line string constants
- #5149: (partial) various documentation problems
- #5156: rare compiler crash with objects
- #5165: ocamlbuild does not pass '-thread' option to ocamlfind
- #5167: camlp4r loops when printing package type
- #5172: camlp4 support for 'module type of' construct
- #5175: in bigarray accesses, make sure bigarray expr is evaluated only once
- #5177: Gc.compact implies Gc.full_major
- #5182: use bytecode version of ocamldoc to generate man pages
- #5184: under Windows, alignment issue with bigarrays mapped from files
- #5188: double-free corruption in bytecode system threads
- #5192: mismatch between words and bytes in interpreting max_young_wosize
- #5202: error in documentation of atan2
- #5209: natdynlink incorrectly detected on BSD systems
- #5213: ocamlbuild should pass '-rectypes' to ocamldoc when needed
- #5217: ocamlfind plugin should add '-linkpkg' for toplevel
- #5228: document the exceptions raised by functions in 'Filename'
- #5229: typo in build script ('TAG_LINE' vs 'TAGLINE')
- #5230: error in documentation of Scanf.Scanning.open_in
- #5234: option -shared reverses order of -cclib options
- #5237: incorrect .size directives generated for x86-32 and x86-64
- #5244: String.compare uses polymorphic compare_val (regression of #4194)
- #5248: regression introduced while fixing #5118
- #5252: typo in docs
- #5258: win32unix: unix fd leak under windows
- #5269: (tentative fix) Wrong ext_ref entries in .annot files
- #5272: caml.el doesn't recognize downto as a keyword
- #5276: issue with ocamlc -pack and recursively-packed modules
- #5280: alignment constraints incorrectly autodetected on MIPS 32
- #5281: typo in error message
- #5308: unused variables not detected in "include (struct .. end)"
- camlp4 revised syntax printing bug in the toplevel (reported on caml-list)
- configure: do not define _WIN32 under cygwin
- Hardened generic comparison in the case where two custom blocks
  are compared and have different sets of custom operations.
- Hardened comparison between bigarrays in the case where the two
  bigarrays have different kinds.
- Fixed wrong autodetection of expm1() and log1p().
- don't add .exe suffix when installing the ocamlmktop shell script
- ocamldoc: minor fixes related to the display of ocamldoc options
- fixed bug with huge values in OCAMLRUNPARAM
- mismatch between declaration and definition of caml_major_collection_slice

Feature wishes:
- #4992: added '-ml-synonym' and '-mli-synonym' options to ocamldep
- #5065: added '-ocamldoc' option to ocamlbuild
- #5139: added possibility to add options to ocamlbuild
- #5158: added access to current camlp4 parsers and printers
- #5180: improved instruction selection for float operations on amd64
- stdlib: added a 'usage_string' function to Arg
- allow with constraints to add a type equation to a datatype definition
- ocamldoc: allow to merge '@before' tags like other ones
- ocamlbuild: allow dependency on file "_oasis"

Other changes:
- Changed default minor heap size from 32k to 256k words.
- Added new operation 'compare_ext' to custom blocks, called when
  comparing a custom block value with an unboxed integer.


Objective Caml 3.12.0 (2 Aug 2010):
-----------------------------------

(Changes that can break existing programs are marked with a "*"  )

Language features:
- Shorthand notation for records: in expressions and patterns,
    { lbl } stands for { lbl = lbl } and { M.lbl } for { M.lbl = lbl }
- Record patterns of the form { lbl = pat; _ } to mark that not all
  labels are listed, purposefully.  (See new warning below.)
- Explicit naming of a generic type; in an expression
  "fun ... (type t) ... -> e", the type t is considered abstract in its
  scope (the arguments that follow it and the body of the function),
  and then replaced by a fresh type variable. In particular, the type
  t can be used in contexts where a type variable is not allowed
  (e.g. for defining an exception in a local module).
- Explicit polymorphic types and polymorphic recursion. In let
  definitions, one can write an explicit polymorphic type just
  immediately the function name; the polymorphism will be enforced,
  and recursive calls may use the polymorphism.
  The syntax is the same as for polymorphic methods:
    "let [rec] <ident> : 'a1 ... 'an. <typexp> = ..."
- First-class packages modules.
  New kind of type expression, for packaged modules: (module PT).
  New kind of expression, to pack a module as a first-class value:
    (module MODEXPR : PT).
  New kind of module expression, to unpack a first-class value as a module:
    (val EXPR : PT).
  PT is a package type of the form "S" or
  "S with type t1 = ... and ... and type tn = ..." (S refers to a module type).
- Local opening of modules in a subexpression.
  Syntax: "let open M in e", or "M.(e)"
- In class definitions, method and instance variable override can now
  be made explicit, by writing "method!", "val!" or "inherit!" in place of
  "method", "val" and "inherit". It is an error to override an
  undefined member (or to use overriding inheritance when nothing get
  overridden). Additionally, these constructs disactivate respectively
  warnings 7 (method override, code 'M') and 13 (instance variable
  override, code 'V'). Note that, by default, warning 7 is inactive
  and warning 13 is active.
- "Destructive" substitution in signatures.
  By writing "<signature> with type t := <typeconstr>" and
  "<signature> with module M := <module-path>" one replaces "t" and "M"
  inside the signature, removing their respective fields. Among other
  uses, this allows to merge two signatures containing identically
  named fields.
* While fixing #4824, also corrected a gaping hole in the type checker,
  which allowed instantiating separately object parameters and instance
  variables in an interface. This hole was here since the beginning of
  ocaml, and as a result many programs using object inheritance in a non
  trivial way will need to be corrected. You can look at lablgtk2 for an
  example.

Compilers and toplevel:
- Warnings are now numbered and can be switched on and off individually.
  The old system with letters referring to sets of warnings is still
  supported.
- New warnings:
  + 9 (code 'R') to signal record patterns without "; _" where
    some labels of the record type are not listed in the pattern.
  + 28 when giving a wildcard argument to a constant constructor in
    a pattern-matching.
  + 29 when an end-of-line appears unescaped in a string constant.
  + 30 when the same constructor or record field is defined twice in
    mutually-recursive type definitions.
* The semantics of warning 7 (code 'M', method override) have changed
  (it now detects all overrides, not just repeated definitions inside
  the same class body), and it is now inactive by default.
- Better error report in case of unbound qualified identifier: if the module
  is unbound this error is reported in the first place.
- Added option '-strict-sequence' to force left hand part of sequence to have
  type unit.
- Added option '-no-app-funct' to turn applicative functors off.
  This option can help working around mysterious type incompatibilities
  caused by the incomplete comparison of applicative paths F(X).t.

Native-code compiler:
- AMD64: shorter and slightly more efficient code generated for
  float comparisons.

Standard library:
- Format: new function ikfprintf analogous to ifprintf with a continuation
  argument.
* #4210, #4245: stricter range checking in string->integer conversion
  functions (int_of_string, Int32.of_string, Int64.of_string,
  Nativeint.of_string).  The decimal string corresponding to
  max_int + 1 is no longer accepted.
- Scanf: to prevent confusion when mixing Scanf scanning functions and direct
  low level input, value Scanf.stdin has been added.
* Random: changed the algorithm to produce better randomness.  Now passes the
  DieHard tests.
- Map: implement functions from Set that make sense for Map.

Other libraries:
* Str: letters that constitute a word now include digits 0-9 and
  underscore _.  This changes the interpretation of '\b' (word boundary)
  in regexps, but is more consistent with other regexp libraries. (#4874).

Ocamlbuild:
- Add support for native dynlink.

New tool:
- ocamlobjinfo: displays various information, esp. dependencies, for
  compiled OCaml files (.cmi, .cmo, .cma, .cmx, .cmxa, .cmxs, and bytecode
  executables).  Extends and makes more official the old objinfo tool
  that was installed by some OCaml packages.

All tools:
- #4857: add a -vnum option to display the version number and nothing else

Bug Fixes:
- #4012: Map.map and Map.mapi do not conform to specification
- #4478: better error messages for type definition mismatches
- #4683: labltk script uses fixed path on windows
- #4742: finalisation function raising an exception blocks other finalisations
- #4775: compiler crash on crazy types (temporary fix)
- #4824: narrowing the type of class parameters with a module specification
- #4862: relaxed value restriction and records
- #4884: optional arguments do not work when Some is redefined
- #4964: parenthesized names for infix functions in annot files
- #4970: better error message for instance variables
- #4975: spelling mistakes
- #4988: contravariance lost with ocamlc -i
- #5004: problem in Buffer.add_channel with very large lengths.
- #5008: on AMD64/MSVC port, rare float corruption during GC.
- #5018: wrong exception raised by Dynlink.loadfile.
- #5057: fatal typing error with local module + functor + polymorphic variant
- Wrong type for Obj.add_offset.
- Small problem with representation of Int32, Int64, and Nativeint constants.
- Use RTLD_LOCAL for native dynlink in private mode.

Objective Caml 3.11.2 (20 Jan 2010):
------------------------------------

Bug fixes:
- #4151: better documentation for min and max w.r.t. NaN
- #4421: ocamlbuild uses wrong compiler for C files
- #4710, #4720: ocamlbuild does not use properly configuration information
- #4750: under some Windows installations, high start-up times for Unix lib
- #4777: problem with scanf and CRLF
- #4783: ocamlmklib problem under Windows
- #4810: BSD problem with socket addresses, e.g. in Unix.getnameinfo
- #4813: issue with parsing of float literals by the GNU assembler
- #4816: problem with modules and private types
- #4818: missed opportunity for type-based optimization of bigarray accesses
- #4821: check for duplicate method names in classes
- #4823: build problem on Mac OS X
- #4836: spurious errors raised by Unix.single_write under Windows
- #4841, #4860, #4930: problem with ocamlopt -output-obj under Mac OS X
- #4847: C compiler error with ocamlc -output-obj under Win64
- #4856: ocamlbuild uses ocamlrun to execute a native plugin
- #4867, #4760: ocamlopt -shared fails on Mac OS X 64bit
- #4873: ocamlbuild ignores "thread" tag when building a custom toplevel
- #4890: ocamlbuild tries to use native plugin on bytecode-only arch
- #4896: ocamlbuild should always pass -I to tools for external libraries
- #4900: small bug triggering automatic compaction even if max_overhead = 1M
- #4902: bug in %.0F printf format
- #4910: problem with format concatenation
- #4922: ocamlbuild recompiles too many files
- #4923: missing \xff for scanf %S
- #4933: functors not handling private types correctly
- #4940: problem with end-of-line in DOS text mode, tentative fix
- #4953: problem compiling bytecode interpreter on ARM in Thumb mode.
- #4955: compiler crash when typing recursive type expression with constraint
- Module Printf: the simple conversion %F (without width indication) was not
           treated properly.
- Makefile: problem with cygwin, flexdll, and symbolic links
- Various build problems with ocamlbuild under Windows with msvc

Feature wishes:
- #2337: (tentative implementation) make ocamldebug use #linenum annotations
- #2464, #4477: custom exception printers
- #3456: Obj.double_field and Obj.set_double_field functions
- #4003: destination directory can be given to Filename.[open_]temp_file
- #4647: Buffer.blit function
- #4685: access to Filename.dir_sep
- #4703: support for debugging embedded applications
- #4723: "clear_rules" function to empty the set of ocamlbuild rules
- #4921: configure option to help cross-compilers

Objective Caml 3.11.1 (12 Jun 2009):
------------------------------------

Bug fixes:
- #4095: ocamldebug: strange behaviour of control-C
- #4403: ocamldebug: improved handling of packed modules
- #4650: Str.regexp_case_fold mis-handling complemented character sets [^a]
- #4660: Scanf.format_from_string: handling of double quote
- #4666: Unix.exec* failure in multithread programs under MacOS X and FreeBSD
- #4667: debugger out of sync with dynlink changes
- #4678: random "out of memory" error with systhreads
- #4690: issue with dynamic loading under MacOS 10.5
- #4692: wrong error message with options -i and -pack passed to ocamlc
- #4699: in otherlibs/dbm, fixed construction of dlldbm.so.
- #4704: error in caml_modify_generational_global_root()
- #4708: (ocamldoc) improved printing of infix identifiers such as "lor".
- #4722: typo in configure script
- #4729: documented the fact that PF_INET6 is not available on all platforms
- #4730: incorrect typing involving abbreviation "type 'a t = 'a"
- #4731: incorrect quoting of arguments passed to the assembler on x86-64
- #4735: Unix.LargeFile.fstat cannot report size over 32bits on Win32
- #4740: guard against possible processor error in
           {Int32,Int64,Nativeint}.{div,rem}
- #4745: type inference wrongly produced non-generalizable type variables.
- #4749: better pipe size for win32unix
- #4756: printf: no error reported for wrong format '%_s'
- #4758: scanf: handling of \<newline> by format '%S'
- #4766: incorrect simplification of some type abbreviations.
- #4768: printf: %F does not respect width and precision specifications
- #4769: Format.bprintf fails to flush
- #4775: fatal error Ctype.Unify during module type-checking (temporary fix)
- #4776: bad interaction between exceptions and classes
- #4780: labltk build problem under Windows.
- #4790: under Windows, map ERROR_NO_DATA Win32 error to EPIPE Unix error.
- #4792: bug in Big_int.big_int_of_int64 on 32-bit platforms.
- #4796: ocamlyacc: missing NUL termination of string
- #4804: bug in Big_int.int64_of_big_int on 32-bit platforms.
- #4805: improving compatibility with the clang C compiler
- #4809: issue with Unix.create_process under Win32
- #4814: ocamlbrowser: crash when editing comments
- #4816: module abbreviations remove 'private' type restrictions
- #4817: Object type gives error "Unbound type parameter .."
- Module Parsing: improved computation of locations when an ocamlyacc rule
                  starts with an empty nonterminal
- Type-checker: fixed wrong variance computation for private types
- x86-32 code generator, MSVC port: wrong "fld" instruction generated.
- ocamlbuild: incorrectly using the compile-time value of $OCAMLLIB
- Makefile problem when configured with -no-shared-libs
- ocamldoc: use dynamic loading in native code

Other changes:
- Improved wording of various error messages
  (contributed by Jonathan Davies, Citrix).
- Support for 64-bit mode in Solaris/x86 (#4670).


Objective Caml 3.11.0 (03 Dec 2008):
------------------------------------

(Changes that can break existing programs are marked with a "*"  )

Language features:
- Addition of lazy patterns: "lazy <pat>" matches suspensions whose values,
  after forcing, match the pattern <pat>.
- Introduction of private abbreviation types "type t = private <type-expr>",
  for abstracting the actual manifest type in type abbreviations.
- Subtyping is now allowed between a private abbreviation and its definition,
  and between a polymorphic method and its monomorphic instance.

Compilers:
- The file name for a compilation unit should correspond to a valid
  identifier (Otherwise dynamic linking and other things can fail, and
  a warning is emitted.)
* Revised -output-obj: the output name must now be provided; its
  extension must be one of .o/.obj, .so/.dll, or .c for the
  bytecode compiler. The compilers can now produce a shared library
  (with all the needed -ccopts/-ccobjs options) directly.
- -dtypes renamed to -annot, records (in .annot files) which function calls
  are tail calls.
- All compiler error messages now include a file name and location, for
  better interaction with Emacs' compilation mode.
- Optimized compilation of "lazy e" when the argument "e" is
  already evaluated.
- Optimized compilation of equality tests with a variant constant constructor.
- The -dllib options recorded in libraries are no longer ignored when
  -use_runtime or -use_prims is used (unless -no_auto_link is
  explicitly used).
- Check that at most one of -pack, -a, -shared, -c, -output-obj is
  given on the command line.
- Optimized compilation of private types as regular manifest types
  (e.g. abbreviation to float, float array or record types with only
   float fields).

Native-code compiler:
- New port: Mac OS X / Intel in 64-bit mode (configure with -cc "gcc -m64").
- A new option "-shared" to produce a plugin that can be dynamically
  loaded with the native version of Dynlink.
- A new option "-nodynlink" to enable optimizations valid only for code
  that is never dynlinked (no-op except for AMD64).
- More aggressive unboxing of floats and boxed integers.
- Can select which assembler and asm options to use at configuration time.

Run-time system:
- New implementation of the page table describing the heap (two-level
  array in 32 bits, sparse hashtable in 64 bits), fixes issues with address
  space randomization on 64-bit OS (#4448).
- New "generational" API for registering global memory roots with the GC,
  enables faster scanning of global roots.
  (The functions are caml_*_generational_global_root in <caml/memory.h>.)
- New function "caml_raise_with_args" to raise an exception with several
  arguments from C.
- Changes in implementation of dynamic linking of C code:
  under Win32, use Alain Frisch's flexdll implementation of the dlopen
  API; under MacOSX, use dlopen API instead of MacOSX bundle API.
- Programs may now choose a first-fit allocation policy instead of
  the default next-fit.  First-fit reduces fragmentation but is
  slightly slower in some cases.

Standard library:
- Parsing library: new function "set_trace" to programmatically turn
  on or off the printing of a trace during parsing.
- Printexc library: new functions "print_backtrace" and "get_backtrace"
  to obtain a stack backtrace of the most recently raised exception.
  New function "record_backtrace" to turn the exception backtrace mechanism
  on or off from within a program.
- Scanf library: fine-tuning of meta format implementation;
  fscanf behaviour revisited: only one input buffer is allocated for any
  given input channel;
  the %n conversion does not count a lookahead character as read.

Other libraries:
- Dynlink: on some platforms, the Dynlink library is now available in
  native code. The boolean Dynlink.is_native allows the program to
  know whether it has been compiled in bytecode or in native code.
- Bigarrays: added "unsafe_get" and "unsafe_set"
  (non-bound-checking versions of "get" and "set").
- Bigarrays: removed limitation "array dimension < 2^31".
- Labltk: added support for TK 8.5.
- Num: added conversions between big_int and int32, nativeint, int64.
  More efficient implementation of Num.quo_num and Num.mod_num.
- Threads: improved efficiency of mutex and condition variable operations;
  improved interaction with Unix.fork (#4577).
- Unix: added getsockopt_error returning type Unix.error.
  Added support for TCP_NODELAY and IPV6_ONLY socket options.
- Win32 Unix: "select" now supports all kinds of file descriptors.
  Improved emulation of "lockf" (#4609).

Tools:
- ocamldebug now supported under Windows (MSVC and Mingw ports),
  but without the replay feature.  (Contributed by Dmitry Bely
  and Sylvain Le Gall at OCamlCore with support from Lexifi.)
- ocamldoc: new option -no-module-constraint-filter to include functions
  hidden by signature constraint in documentation.
- ocamlmklib and ocamldep.opt now available under Windows ports.
- ocamlmklib no longer supports the -implib option.
- ocamlnat: an experimental native toplevel (not built by default).

Camlp4:
* programs linked with camlp4lib.cma now also need dynlink.cma.

Bug fixes:
- Major GC and heap compaction: fixed bug involving lazy values and
  out-of-heap pointers.
- #3915: updated most man pages.
- #4261: type-checking of recursive modules
- #4308: better stack backtraces for "spontaneous" exceptions such as
  Stack_overflow, Out_of_memory, etc.
- #4338: Str.global_substitute, Str.global_replace and the Str.*split*
  functions are now tail-recursive.
- #4503: fixed bug in classify_float on ARM.
- #4512: type-checking of recursive modules
- #4517: crash in ocamllex-generated lexers.
- #4542: problem with return value of Unix.nice.
- #4557: type-checking of recursive modules.
- #4562: strange %n semantics in scanf.
- #4564: add note "stack is not executable" to object files generated by
  ocamlopt (Linux/x86, Linux/AMD64).
- #4566: bug in Ratio.approx_ratio_fix and Num.approx_num_fix.
- #4582: clarified the documentation of functions in the String module.
- #4583: stack overflow in "ocamlopt -g" during closure conversion pass.
- #4585: ocamldoc and "val virtual" declarations.
- #4587: ocamldoc and escaped @ characters.
- #4605: Buffer.add_substitute was sometime wrong when target string had
           backslashes.
- #4614: Inconsistent declaration of CamlCBCmd in LablTk library.


Objective Caml 3.10.2 (29 Feb 2008):
------------------------------------

Bug fixes:
- #3410 (partial) Typo in ocamldep man page
- #3952 (partial) ocamlopt: allocation problems on ARM
- #4339 (continued) ocamlopt: problems on HPPA
- #4455 str.mli not installed under Windows
- #4473 crash when accessing float array with polymorphic method
- #4480 runtime would not compile without gcc extensions
- #4481 wrong typing of exceptions with object arguments
- #4490 typo in error message
- Random crash on 32-bit when major_heap_increment >= 2^22
- Big performance bug in Weak hashtables
- Small bugs in the make-package-macosx script
- Bug in typing of polymorphic variants (reported on caml-list)


Objective Caml 3.10.1 (11 Jan 2008):
------------------------------------

Bug fixes:
- #3830 small bugs in docs
- #4053 compilers: improved compilation time for large variant types
- #4174 ocamlopt: fixed ocamlopt -nopervasives
- #4199 otherlibs: documented a small problem in Unix.utimes
- #4280 camlp4: parsing of identifier (^)
- #4281 camlp4: parsing of type constraint
- #4285 runtime: cannot compile under AIX
- #4286 ocamlbuild: cannot compile under AIX and SunOS
- #4288 compilers: including a functor application with side effects
- #4295 camlp4 toplevel: synchronization after an error
- #4300 ocamlopt: crash with backtrace and illegal array access
- #4302 camlp4: list comprehension parsing problem
- #4304 ocamlbuild: handle -I correctly
- #4305 stdlib: alignment of Arg.Symbol
- #4307 camlp4: assertion failure
- #4312 camlp4: accept "let _ : int = 1"
- #4313 ocamlbuild: -log and missing directories
- #4315 camlp4: constraints in classes
- #4316 compilers: crash with recursive modules and Lazy
- #4318 ocamldoc: installation problem with Cygwin (tentative fix)
- #4322 ocamlopt: stack overflow under Windows
- #4325 compilers: wrong error message for unused var
- #4326 otherlibs: marshal Big_int on win64
- #4327 ocamlbuild: make emacs look for .annot in _build directory
- #4328 camlp4: stack overflow with nil nodes
- #4331 camlp4: guards on fun expressions
- #4332 camlp4: parsing of negative 32/64 bit numbers
- #4336 compilers: unsafe recursive modules
- #4337 (note) camlp4: invalid character escapes
- #4339 ocamlopt: problems on HP-UX (tentative fix)
- #4340 camlp4: wrong pretty-printing of optional arguments
- #4348 ocamlopt: crash on Mac Intel
- #4349 camlp4: bug in private type definitions
- #4350 compilers: type errors with records and polymorphic variants
- #4352 compilers: terminal recursion under Windows (tentative fix)
- #4354 ocamlcp: mismatch with ocaml on polymorphic let
- #4358 ocamlopt: float constants wrong on ARM
- #4360 ocamldoc: string inside comment
- #4365 toplevel: wrong pretty-printing of polymorphic variants
- #4373 otherlibs: leaks in win32unix
- #4374 otherlibs: threads module not initialized
- #4375 configure: fails to build on bytecode-only architectures
- #4377 runtime: finalisation of infix pointers
- #4378 ocamlbuild: typo in plugin.ml
- #4379 ocamlbuild: problem with plugins under Windows
- #4382 compilers: typing of polymorphic record fields
- #4383 compilers: including module with private type
- #4385 stdlib: Int32/Int64.format are unsafe
- #4386 otherlibs: wrong signal numbers with Unix.sigprocmask etc.
- #4387 ocamlbuild: build directory not used properly
- #4392 ocamldep: optional argument of class
- #4394 otherlibs: infinite loops in Str
- #4397 otherlibs: wrong size for flag arrays in win32unix
- #4402 ocamldebug: doesn't work with -rectypes
- #4410 ocamlbuild: problem with plugin and -build
- #4411 otherlibs: crash with Unix.access under Windows
- #4412 stdlib: marshalling broken on 64 bit architectures
- #4413 ocamlopt: crash on AMD64 with out-of-bound access and reraise
- #4417 camlp4: pretty-printing of unary minus
- #4419 camlp4: problem with constraint in type class
- #4426 compilers: problem with optional labels
- #4427 camlp4: wrong pretty-printing of lists of functions
- #4433 ocamlopt: fails to build on MacOSX 10.5
- #4435 compilers: crash with objects
- #4439 fails to build on MacOSX 10.5
- #4441 crash when build on sparc64 linux
- #4442 stdlib: crash with weak pointers
- #4446 configure: fails to detect X11 on MacOSX 10.5
- #4448 runtime: huge page table on 64-bit architectures
- #4450 compilers: stack overflow with recursive modules
- #4470 compilers: type-checking of recursive modules too restrictive
- #4472 configure: autodetection of libX11.so on Fedora x86_64
- printf: removed (partially implemented) positional specifications
- polymorphic < and <= comparisons: some C compiler optimizations
  were causing incorrect results when arguments are incomparable

New features:
- made configure script work on PlayStation 3
- ARM port: brought up-to-date for Debian 4.0 (Etch)
- many other small changes and bugfixes in camlp4, ocamlbuild, labltk,
  emacs files


Objective Caml 3.10.0 (18 May 2007):
------------------------------------

(Changes that can break existing programs are marked with a "*"  )

Language features:
- Added virtual instance variables in classes "val virtual v : t"
* Changed the behaviour of instance variable overriding; the new
  definition replaces the old one, rather than creating a new
  variable.

New tools:
- ocamlbuild: compilation manager for OCaml applications and libraries.
  See draft documentation at http://gallium.inria.fr/~pouillar/
* Camlp4: heavily revised implementation, new API.

New ports:
- MacOS X PowerPC 64 bits.
- MS Windows 64 bits (x64) using the Microsoft PSDK toolchain.
- MS Windows 32 bits using the Visual Studio 2005 toolchain.

Compilers:
- Faster type-checking of functor applications.
- Referencing an interface compiled with -rectypes from a module
    not compiled with -rectypes is now an error.
- Revised the "fragile matching" warning.

Native-code compiler:
- Print a stack backtrace on an uncaught exception.
  (Compile and link with ocamlopt -g; execute with OCAMLRUNPARAM=b.)
  Supported on Intel/AMD in 32 and 64 bits, PPC in 32 and 64 bits.
- Stack overflow detection on MS Windows 32 bits (courtesy O. Andrieu).
- Stack overflow detection on MacOS X PPC and Intel.
- Intel/AMD 64 bits: generate position-independent code by default.
- Fixed bug involving -for-pack and missing .cmx files (#4124).
- Fixed bug causing duplication of literals  (#4152).

Run-time system:
- C/Caml interface functions take "char const *" arguments
  instead of "char *" when appropriate.
- Faster string comparisons (fast case if strings are ==).

Standard library:
- Refined typing of format strings (type format6).
- Printf, Format: new function ifprintf that consumes its arguments
    and prints nothing (useful to print conditionally).
- Scanf:
    new function format_from_string to convert a string to a format string;
    new %r conversion to accommodate user defined scanners.
- Filename: improved Win32 implementation of Filename.quote.
- List: List.nth now tail-recursive.
- Sys: added Sys.is_directory.  Some functions (e.g. Sys.command) that
    could incorrectly raise Sys_io_blocked now raise Sys_error as intended.
- String and Char: the function ``escaped'' now escapes all the characters
    especially handled by the compiler's lexer (#4220).

Other libraries:
- Bigarray: mmap_file takes an optional argument specifying
    the start position of the data in the mapped file.
- Dynlink: now defines only two modules, Dynlink and Dynlinkaux (internal),
    reducing risks of name conflicts with user modules.
- Labltk under Win32: now uses Tcl/Tk 8.4 instead of 8.3 by default.
- VM threads: improved performance of I/O operations (less polling).
- Unix: new function Unix.isatty.
- Unix emulation under Win32:
    fixed incorrect error reporting in several functions (#4097);
    better handling of channels opened on sockets (#4098);
    fixed GC bug in Unix.system (#4112).

Documentation generator (OCamldoc):
- correctly handle '?' in value names (#4215)
- new option -hide-warnings not to print ocamldoc warnings

Lexer generator (ocamllex): improved error reporting.

License: fixed a typo in the "special exception" to the LGPL.


Objective Caml 3.09.3 (15 Sep 2006):
------------------------------------

Bug fixes:
- ocamldoc: -using modtype constraint to filter module elements displayed
    in doc #4016
- ocamldoc: error in merging of top dependencies of modules #4007
- ocamldoc: -dot-colors has no effect #3981
- ocamdloc: missing crossref in text from intro files #4066
- compilers: segfault with recursive modules #4008
- compilers: infinite loop when compiling objects #4018
- compilers: bad error message when signature mismatch #4001
- compilers: infinite loop with -rectypes #3999
- compilers: contravariance bug in private rows
- compilers: unsafe cast with polymorphic exception #4002
- native compiler: bad assembly code generated for AMD64 #4067
- native compiler: stack alignment problems on MacOSX/i386 #4036
- stdlib: crash in marshalling #4030
- stdlib: crash when closing a channel twice #4039
- stdlib: memory leak in Sys.readdir #4093
- C interface: better definition of CAMLreturn #4068
- otherlibs/unix: crash in gethostbyname #3043
- tools: subtle problem with unset in makefile #4048
- camlp4: install pa_o_fast.o #3812
- camlp4: install more modules #3689

New features:
- ocamldoc: name resolution in cross-referencing {!name}: if name is not
    found, then it is searched in the parent module/class, and in the parent
    of the parent, and so on until it is found.
- ocamldoc: new option -short-functors to use a short form to display
    functors in html generator #4017
- ocamlprof: added "-version" option



Objective Caml 3.09.2 (14 Apr 2006):
------------------------------------

Bug fixes:
- Makefile: problem with "make world.opt" #3954
- compilers: problem compiling several modules with one command line #3979
- compilers,ocamldoc: error message that Emacs cannot parse
- compilers: crash when printing type error #3968
- compilers: -dtypes wrong for monomorphic type variables #3894
- compilers: wrong warning on optional arguments #3980
- compilers: crash when wrong use of type constructor in let rec #3976
- compilers: better wording of "statement never returns" warning #3889
- runtime: inefficiency of signal handling #3990
- runtime: crashes with I/O in multithread programs #3906
- camlp4: empty file name in error messages #3886
- camlp4: stack overflow #3948
- otherlibs/labltk: ocamlbrowser ignores its command line options #3961
- otherlibs/unix: Unix.times wrong under Mac OS X #3960
- otherlibs/unix: wrong doc for execvp and execvpe #3973
- otherlibs/win32unix: random crash in Unix.stat #3998
- stdlib: update_mod not found under Windows #3847
- stdlib: Filename.dirname/basename wrong on Win32 #3933
- stdlib: incomplete documentation of Pervasives.abs #3967
- stdlib: Printf bugs #3902, #3955
- tools/checkstack.c: missing include
- yacc: crash when given argument "-" #3956

New features:
- ported to MacOS X on Intel #3985
- configure: added support for GNU Hurd #3991

Objective Caml 3.09.1 (4 Jan 2006):
-----------------------------------

Bug fixes:
- compilers: raise not_found with -principal #3855
- compilers: assert failure in typeclass.cml #3856
- compilers: assert failure in typing/ctype.ml #3909
- compilers: fatal error exception Ctype.Unify #3918
- compilers: spurious warning Y in objects #3868
- compilers: spurious warning Z on loop index #3907
- compilers: error message that emacs cannot parse
- ocamlopt: problems with -for-pack/-pack #3825, #3826, #3919
- ocamlopt: can't produce shared libraries on x86_64 #3869, #3924
- ocamlopt: float alignment problem on SPARC #3944
- ocamlopt: can't compile on MIPS #3936
- runtime: missing dependence for ld.conf
- runtime: missing dependence for .depend.nt #3880
- runtime: memory leak in caml_register_named_value #3940
- runtime: crash in Marshal.to_buffer #3879
- stdlib: Sys.time giving wrong results on Mac OS X #3850
- stdlib: Weak.get_copy causing random crashes in rare cases
- stdlib, debugger, labltk: use TMPDIR if set #3895
- stdlib: scanf bug on int32 and nativeint #3932
- camlp4: mkcamlp4 option parsing problem #3941
- camlp4: bug in pretty-printing of lazy/assert/new
- camlp4: update the unmaintained makefile for _loc name
- ocamldoc: several fixes see ocamldoc/Changes.txt
- otherlibs/str: bug in long sequences of alternatives #3783
- otherlibs/systhreads: deadlock in Windows #3910
- tools: update dumpobj to handle new event format #3873
- toplevel: activate warning Y in toplevel #3832

New features:
- otherlibs/labltk: browser uses menu bars instead of menu buttons

Objective Caml 3.09.0 (27 Oct 2006):
------------------------------------

(Changes that can break existing programs are marked with a "*"  )

Language features:
- Introduction of private row types, for abstracting the row in object
  and variant types.

Type checking:
- Polymorphic variants with at most one constructor [< `A of t] are no
  longer systematically promoted to the exact type [`A of t]. This was
  more confusing than useful, and created problems with private row
  types.

Both compilers:
- Added warnings 'Y' and 'Z' for local variables that are bound but
  never used.
- Added warning for some uses non-returning functions (e.g. raise), when they
  are passed extra arguments, or followed by extra statements.
- Pattern matching: more prudent compilation in case of guards; fixed #3780.
- Compilation of classes: reduction in size of generated code.
- Compilation of "module rec" definitions: fixed a bad interaction with
  structure coercion (to a more restrictive signature).

Native-code compiler (ocamlopt):
* Revised implementation of the -pack option (packing of several compilation
  units into one).  The .cmx files that are to be packed with
  "ocamlopt -pack -o P.cmx" must be compiled with "ocamlopt -for-pack P".
  In exchange for this additional constraint, ocamlopt -pack is now
  available on all platforms (no need for binutils).
* Fixed wrong evaluation order for arguments to certain inlined functions.
- Modified code generation for "let rec ... and ..." to reduce compilation
  time (which was quadratic in the number of mutually-recursive functions).
- x86 port: support tail-calls for functions with up to 21 arguments.
- AMD64 port, Linux: recover from system stack overflow.
- Sparc port: more portable handling of out-of-bound conditions
  on systems other than Solaris.

Standard library:
- Pervasives: faster implementation of close_in, close_out.
  set_binary_mode_{out,in} now working correctly under Cygwin.
- Printf: better handling of partial applications of the printf functions.
- Scanf: new function sscanf_format to read a format from a
  string. The type of the resulting format is dynamically checked and
  should be the type of the template format which is the second argument.
- Scanf: no more spurious lookahead attempt when the end of file condition
  is set and a correct token has already been read and could be returned.

Other libraries:
- System threads library: added Thread.sigmask; fixed race condition
  in signal handling.
- Bigarray library: fixed bug in Array3.of_array.
- Unix library: use canonical signal numbers in results of Unix.wait*;
  hardened Unix.establish_server against EINTR errors.

Run-time system:
- Support platforms where sizeof(void *) = 8 and sizeof(long) = 4.
- Improved and cleaned up implementation of signal handling.

Replay debugger:
- Improved handling of locations in source code.

OCamldoc:
- extensible {foo } syntax
- user can give .txt files on the command line, containing ocamldoc formatted
  text, to be able to include bigger texts out of source files
- -o option is now used by the html generator to indicate the prefix
  of generated index files (to avoid conflict when a Index module exists
  on case-insensitive file systems).

Miscellaneous:
- Configuration information is installed in `ocamlc -where`/Makefile.config
  and can be used by client Makefiles or shell scripts.

Objective Caml 3.08.4 (11 Aug 2005):
------------------------------------

New features:
- configure: find X11 config in some 64-bit Linux distribs
- ocamldoc: (**/**) can be canceled with another (**/**) #3665
- graphics: added resize_window
- graphics: check for invalid arguments to drawing primitives #3595
- ocamlbrowser: use windows subsystem on mingw

Bug fixes:
- ocamlopt: code generation problem on AMD64 #3640
- wrong code generated for some classes #3576
- fatal error when compiling some OO code #3745
- problem with comparison on constant constructors #3608
- camlp4: cryptic error message #3592
- camlp4: line numbers in multi-line antiquotations #3549
- camlp4: problem with make depend
- camlp4: parse error with :> #3561
- camlp4: ident conversion problem with val/contents/contents__
- camlp4: several small parsing problems #3688
- ocamldebug: handling of spaces in executable file name #3736
- emacs-mode: problem when caml-types-buffer is deleted by user #3704
- ocamldoc: extra backslash in ocamldoc man page #3687
- ocamldoc: improvements to HTML display #3698
- ocamldoc: escaping of @ in info files
- ocamldoc: escaping of . and \ in man pages #3686
- ocamldoc: better error reporting of misplaced comments
- graphics: fixed .depend file #3558
- graphics: segfault with threads and graphics #3651
- nums: several bugs: #3718, #3719, others
- nums: inline asm problems with gcc 4.0 #3604, #3637
- threads: problem with backtrace
- unix: problem with getaddrinfo #3565
- stdlib: documentation of Int32.rem and Int64.rem #3573
- stdlib: documentation of List.rev_map2 #3685
- stdlib: wrong order in Map.fold #3607
- stdlib: documentation of maximum float array length #3714
- better detection of cycles when using -rectypes
- missing case of module equality #3738
- better error messages for unbound type variables
- stack overflow while printing type error message #3705
- assert failure when typing some classes #3638
- bug in type_approx
- better error messages related to type variance checking
- yacc: avoid name capture for idents of the Parsing module


Objective Caml 3.08.3 (24 Mar 2005):
------------------------------------

New features:
- support for ocamlopt -pack under Mac OS X (#2634, #3320)
- ignore unknown warning options for forward and backward compatibility
- runtime: export caml_compare_unordered (#3479)
- camlp4: install argl.* files (#3439)
- ocamldoc: add -man-section option
- labltk: add the "solid" relief option (#3343)

Bug fixes:
- typing: fix unsoundness in type declaration variance inference.
    Type parameters which are constrained must now have an explicit variant
    annotation, otherwise they are invariant. This is not backward
    compatible, so this might break code which either uses subtyping or
    uses the relaxed value restriction (i.e. was not typable before 3.07)
- typing: erroneous partial match warning for polymorphic variants (#3424)
- runtime: handle the case of an empty command line (#3409, #3444)
- stdlib: make Sys.executable_name an absolute path in native code (#3303)
- runtime: fix memory leak in finalise.c
- runtime: auto-trigger compaction even if gc is called manually (#3392)
- stdlib: fix segfault in Obj.dup on zero-sized values (#3406)
- camlp4: correct parsing of the $ identifier (#3310, #3469)
- windows (MS tools): use link /lib instead of lib (#3333)
- windows (MS tools): change default install destination
- autoconf: better checking of SSE2 instructions (#3329, #3330)
- graphics: make close_graph close the X display as well as the window (#3312)
- num: fix big_int_of_string (empty string) (#3483)
- num: fix big bug on 64-bit architecture (#3299)
- str: better documentation of string_match and string_partial_match (#3395)
- unix: fix file descriptor leak in Unix.accept (#3423)
- unix: miscellaneous clean-ups
- unix: fix documentation of Unix.tm (#3341)
- graphics: fix problem when allocating lots of images under Windows (#3433)
- compiler: fix error message with -pack when .cmi is missing (#3028)
- cygwin: fix problem with compilation of camlheader (#3485)
- stdlib: Filename.basename doesn't return an empty string any more (#3451)
- stdlib: better documentation of Open_excl flag (#3450)
- ocamlcp: accept -thread option (#3511)
- ocamldep: handle spaces in file names (#3370)
- compiler: remove spurious warning in pattern-matching on variants (#3424)
- windows: better handling of InterpreterPath registry entry (#3334, #3432)


Objective Caml 3.08.2 (22 Nov 2004):
------------------------------------

Bug fixes:
- runtime: memory leak when unmarshalling big data structures (#3247)
- camlp4: incorrect line numbers in errors (#3188)
- emacs: xemacs-specific code, wrong call to "sit-for"
- ocamldoc: "Lexing: empty token" (#3173)
- unix: problem with close_process_* (#3191)
- unix: possible coredumps (#3252)
- stdlib: wrong order in Set.fold (#3161)
- ocamlcp: array out of bounds in profiled programs (#3267)
- yacc: problem with polymorphic variant types for grammar entries (#3033)

Misc:
- export <caml/printexc.h> for caml_format_exception (#3080)
- clean up caml_search_exe_in_path (maybe #3079)
- camlp4: new function "make_lexer" for new-style locations
- unix: added missing #includes (#3088)


Objective Caml 3.08.1 (19 Aug 2004):
------------------------------------

Licence:
- The emacs files are now under GPL
- Slightly relaxed some conditions of the QPL

Bug fixes:
- ld.conf now generated at compile-time instead of install-time
- fixed -pack on Windows XP (#2935)
- fixed Obj.tag (#2946)
- added support for multiple dlopen in Darwin
- run ranlib when installing camlp4 libraries (#2944)
- link camlp4opt with -linkall (#2949)
- camlp4 parsing of patterns now conforms to normal parsing (#3015)
- install camlp4 *.cmx files (#2955)
- fixed handling of linefeed in string constants in camlp4 (#3074)
- ocamldoc: fixed display of class parameters in HTML and LaTeX (#2994)
- ocamldoc: fixed display of link to class page in html (#2994)
- Windows toplevel GUI: assorted fixes (including #2932)

Misc:
- added -v option to ocamllex
- ocamldoc: new -intf and -impl options supported (#3036)

Objective Caml 3.08.0 (13 Jul 2004):
------------------------------------

(Changes that can break existing programs are marked with a "*"  )

Language features:
- Support for immediate objects, i.e. objects defined without going
  through a class.  (Syntax is "object <fields and methods> end".)

Type-checking:
- When typing record construction and record patterns, can omit
  the module qualification on all labels except one.  I.e.
  { M.l1 = ...; l2 = ... } is interpreted as { M.l1 = ...; M.l2 = ... }

Both compilers:
- More compact compilation of classes.
- Much more efficient handling of class definitions inside functors
  or local modules.
- Simpler representation for method tables. Objects can now be marshaled
  between identical programs with the flag Marshal.Closures.
- Improved error messages for objects and variants.
- Improved printing of inferred module signatures (toplevel and ocamlc -i).
  Recursion between type, class, class type and module definitions is now
  correctly printed.
- The -pack option now accepts compiled interfaces (.cmi files) in addition
  to compiled implementations (.cmo or .cmx).
* A compile-time error is signaled if an integer literal exceeds the
  range of representable integers.
- Fixed code generation error for "module rec" definitions.
- The combination of options -c -o sets the name of the generated
  .cmi / .cmo / .cmx files.

Bytecode compiler:
- Option -output-obj is now compatible with Dynlink and
  with embedded toplevels.

Native-code compiler:
- Division and modulus by zero correctly raise exception Division_by_zero
  (instead of causing a hardware trap).
- Improved compilation time for the register allocation phase.
- The float constant -0.0 was incorrectly treated as +0.0 on some processors.
- AMD64: fixed bugs in asm glue code for GC invocation and exception raising
  from C.
- IA64: fixed incorrect code generated for "expr mod 1".
- PowerPC: minor performance tweaks for the G4 and G5 processors.

Standard library:
* Revised handling of NaN floats in polymorphic comparisons.
  The polymorphic boolean-valued comparisons (=, <, >, etc) now treat
  NaN as uncomparable, as specified by the IEEE standard.
  The 3-valued comparison (compare) treats NaN as equal to itself
  and smaller than all other floats.  As a consequence, x == y
  no longer implies x = y but still implies compare x y = 0.
* String-to-integer conversions now fail if the result overflows
  the range of integers representable in the result type.
* All array and string access functions now raise
  Invalid_argument("index out of bounds") when a bounds check fails.
  In earlier releases, different exceptions were raised
  in bytecode and native-code.
- Module Buffer: new functions Buffer.sub, Buffer.nth
- Module Int32: new functions Int32.bits_of_float, Int32.float_of_bits.
- Module Map: new functions is_empty, compare, equal.
- Module Set: new function split.
* Module Gc: in-order finalisation, new function finalise_release.

Other libraries:
- The Num library: complete reimplementation of the C/asm lowest
  layer to work around potential licensing problems.
  Improved speed on the PowerPC and AMD64 architectures.
- The Graphics library: improved event handling under MS Windows.
- The Str library: fixed bug in "split" functions with nullable regexps.
- The Unix library:
   . Added Unix.single_write.
   . Added support for IPv6.
   . Bug fixes in Unix.closedir.
   . Allow thread switching on Unix.lockf.

Runtime System:
* Name space depollution: all global C identifiers are now prefixed
  with "caml" to avoid name clashes with other libraries.  This
  includes the "external" primitives of the standard runtime.

Ports:
- Windows ports: many improvements in the OCamlWin toplevel application
  (history, save inputs to file, etc).  Contributed by Christopher A. Watford.
- Native-code compilation supported for HPPA/Linux. Contributed by Guy Martin.
- Removed support for MacOS9.  Mac OS 9 is obsolete and the port was not
  updated since 3.05.
- Removed ocamlopt support for HPPA/Nextstep and Power/AIX.

Ocamllex:
- #line directives in the input file are now accepted.
- Added character set concatenation operator "cset1 # cset2".

Ocamlyacc:
- #line directives in the input file are now accepted.

Camlp4:
* Support for new-style locations (line numbers, not just character numbers).
- See camlp4/CHANGES and camlp4/ICHANGES for more info.


Objective Caml 3.07 (29 Sep 2003):
----------------------------------

Language features:
- Experimental support for recursive module definitions
      module rec A : SIGA = StructA and B : SIGB = StructB and ...
- Support for "private types", or more exactly concrete data types
  with private constructors or labels.  These data types can be
  de-structured normally in pattern matchings, but values of these
  types cannot be constructed directly outside of their defining module.
- Added integer literals of types int32, nativeint, int64
  (written with an 'l', 'n' or 'L' suffix respectively).

Type-checking:
- Allow polymorphic generalization of covariant parts of expansive
  expressions.  For instance, if f: unit -> 'a list, "let x = f ()"
  gives "x" the generalized type forall 'a. 'a list, instead of '_a list
  as before.
- The typing of polymorphic variants in pattern matching has changed.
  It is intended to be more regular, sticking to the principle of "closing
  only the variants which would be otherwise incomplete". Two potential
  consequences: (1) some types may be left open which were closed before,
  and the resulting type might not match the interface anymore (expected to
  be rare); (2) in some cases an incomplete match may be generated.
- Lots of bug fixes in the handling of polymorphism and recursion inside
  types.
- Added a new "-dtypes" option to ocamlc/ocamlopt, and an emacs extension
  "emacs/caml-types.el".  The compiler option saves inferred type information
  to file *.annot, and the emacs extension allows the user to look at the
  type of any subexpression in the source file.  Works even in the case
  of a type error (all the types computed up to the error are available).
  This new feature is also supported by ocamlbrowser.
- Disable "method is overridden" warning when the method was explicitly
  redefined as virtual beforehand (i.e. not through inheritance). Typing
  and semantics are unchanged.

Both compilers:
- Added option "-dtypes" to dump detailed type information to a file.
- The "-i" option no longer generates compiled files, it only prints
  the inferred types.
- The sources for the module named "Mod" can be placed either in Mod.ml or
  in mod.ml.
- Compilation of "let rec" on non-functional values: tightened some checks,
  relaxed some other checks.
- Fixed wrong code that was generated for "for i = a to max_int"
  or "for i = a downto min_int".
- An explicit interface Mod.mli can now be provided for the module obtained
  by ocamlc -pack -o Mod.cmo ... or ocamlopt -pack -o Mod.cmx ...
- Revised internal handling of source code locations, now handles
  preprocessed code better.
- Pattern-matching bug on float literals fixed.
- Minor improvements on pattern-matching over variants.
- More efficient compilation of string comparisons and the "compare" function.
- More compact code generated for arrays of constants.
- Fixed GC bug with mutable record fields of type "exn".
- Added warning "E" for "fragile patterns": pattern matchings that would
  not be flagged as partial if new constructors were added to the data type.

Bytecode compiler:
- Added option -vmthread to select the threads library with VM-level
  scheduling.  The -thread option now selects the system threads library.

Native-code compiler:
- New port: AMD64 (Opteron).
- Fixed instruction selection bug on expressions of the kind (raise Exn)(arg).
- Several bug fixes in ocamlopt -pack (tracking of imported modules,
  command line too long).
- Signal handling bug fixed.
- x86 port:
    Added -ffast-math option to use inline trigo and log functions.
    Small performance tweaks for the Pentium 4.
    Fixed illegal "imul" instruction generated by reloading phase.
- Sparc port:
    Enhanced code generation for Sparc V8 (option -march=v8) and
    Sparc V9 (option -march=v9).
    Profiling support added for Solaris.
- PowerPC port:
    Keep stack 16-aligned for compatibility with C calling conventions.

Toplevel interactive system:
- Tightened interface consistency checks between .cmi files, .cm[oa] files
  loaded by #load, and the running toplevel.
- #trace on mutually-recursive functions was broken, works again.
- Look for .ocamlinit file in home directory in addition to the current dir.

Standard library:
- Match_failure and Assert_failure exceptions now report
  (file, line, column), instead of (file, starting char, ending char).
- float_of_string, int_of_string: some ill-formed input strings were not
    rejected.
- Added format concatenation, string_of_format, format_of_string.
- Module Arg: added new option handlers Set_string, Set_int, Set_float,
    Symbol, Tuple.
- Module Format: tag handling is now turned off by default,
    use [Format.set_tags true] to activate.
- Modules Lexing and Parsing: added better handling of positions
    in source file.  Added function Lexing.flush_input.
- Module Scanf: %n and %N formats to count characters / items read so far;
    assorted bug fixes, %! to match end of input. New ``_'' special
    flag to skip reresulting value.
- Module Format: tags are not activated by default.
- Modules Set and Map: fixed bugs causing trees to become unbalanced.
- Module Printf: less restrictive typing of kprintf.
- Module Random: better seeding; functions to generate random int32, int64,
    nativeint; added support for explicit state management.
- Module Sys: added Sys.readdir for reading the contents of a directory.

Runtime system:
- output_value/input_value: fixed bug with large blocks (>= 4 Mwords)
  produced on a 64-bit platform and incorrectly read back on a 32-bit
  platform.
- Fixed memory compaction bug involving input_value.
- Added MacOS X support for dynamic linking of C libraries.
- Improved stack backtraces on uncaught exceptions.
- Fixed float alignment problem on Sparc V9 with gcc 3.2.

Other libraries:
- Dynlink:
    By default, dynamically-loaded code now has access to all
      modules defined by the program; new functions Dynlink.allow_only
      and Dynlink.prohibit implement access control.
    Fixed Dynlink problem with files generated with ocamlc -pack.
    Protect against references to modules not yet fully initialized.
- LablTK/CamlTK: added support for TCL/TK 8.4.
- Str: reimplemented regexp matching engine, now less buggy, faster,
    and LGPL instead of GPL.
- Graphics: fixed draw_rect and fill_rect bug under X11.
- System threads and bytecode threads libraries can be both installed.
- System threads: better implementation of Thread.exit.
- Bytecode threads: fixed two library initialization bugs.
- Unix: make Unix.openfile blocking to account for named pipes;
  GC bug in Unix.*stat fixed; fixed problem with Unix.dup2 on Windows.

Ocamllex:
- Can name parts of the matched input text, e.g.
    "0" (['0'-'7']+ as s) { ... s ... }

Ocamldebug:
- Handle programs that run for more than 2^30 steps.

Emacs mode:
- Added file caml-types.el to interactively display the type information
  saved by option -dtypes.

Win32 ports:
- Cygwin port: recognize \ as directory separator in addition to /
- MSVC port: ocamlopt -pack works provided GNU binutils are installed.
- Graphics library: fixed bug in Graphics.blit_image; improved event handling.

OCamldoc:
- new ty_code field for types, to keep code of a type (with option -keep-code)
- new ex_code field for types, to keep code of an exception
    (with option -keep-code)
- some fixes in html generation
- don't overwrite existing style.css file when generating HTML
- create the ocamldoc.sty file when generating LaTeX (if nonexistent)
- man pages are now installed in man/man3 rather than man/mano
- fix: empty [] in generated HTML indexes


Objective Caml 3.06 (20 Aug 2002):
----------------------------------

Type-checking:
- Apply value restriction to polymorphic record fields.

Run-time system:
- Fixed GC bug affecting lazy values.

Both compilers:
- Added option "-version" to print just the version number.
- Fixed wrong dependencies in .cmi generated with the -pack option.

Native-code compiler:
- Fixed wrong return value for inline bigarray assignments.

Libraries:
- Unix.getsockopt: make sure result is a valid boolean.

Tools:
- ocamlbrowser: improved error reporting; small Win32 fixes.

Windows ports:
- Fixed two problems with the Mingw port under Cygwin 1.3.


Objective Caml 3.05 (29 Jul 2002):
----------------------------------

Language features:
- Support for polymorphic methods and record fields.
- Allows _ separators in integer and float literals, e.g. 1_000_000.

Type-checker:
- New flag -principal to enforce principality of type inference.
- Fixed subtle typing bug with higher-order functors.
- Fixed several complexity problems; changed (again) the  behaviour of
  simple coercions.
- Fixed various bugs with objects and polymorphic variants.
- Improved some error messages.

Both compilers:
- Added option "-pack" to assemble several compilation units as one unit
  having the given units as sub-modules.
- More precise detection of unused sub-patterns in "or" patterns.
- Warnings for ill-formed \ escapes in string and character literals.
- Protect against spaces and other special characters in directory names.
- Added interface consistency check when building a .cma or .cmxa library.
- Minor reduction in code size for class initialization code.
- Added option "-nostdlib" to ignore standard library entirely.

Bytecode compiler:
- Fixed issue with ocamlc.opt and dynamic linking.

Native-code compiler:
- Added link-time check for multiply-defined module names.
- Fixed GC bug related to constant constructors of polymorphic variant types.
- Fixed compilation bug for top-level "include" statements.
- PowerPC port: work around limited range for relative branches,
  thus removing assembler failures on large functions.
- IA64 port: fixed code generation bug for 3-way constructor matching.

Toplevel interactive system:
- Can load object files given on command line before starting up.
- ocamlmktop: minimized possibility of name clashes with user-provided modules.

Run-time system:
- Minor garbage collector no longer recursive.
- Better support for lazy data in the garbage collector.
- Fixed issues with the heap compactor.
- Fixed issues with finalized Caml values.
- The type "int64" is now supported on all platforms: we use software
  emulation if the C compiler doesn't support 64-bit integers.
- Support for float formats that are neither big-endian nor little-endian
  (one known example: the ARM).
- Fixed bug in callback*_exn functions in the exception-catching case.
- Work around gcc 2.96 bug on RedHat 7.2 and Mandrake 8.0, 8.1 among others.
- Stub DLLs now installed in subdir stublibs/ of standard library dir.

Standard library:
- Protect against integer overflow in sub-string and sub-array bound checks.
- New module Complex implementing arithmetic over complex numbers.
- New module Scanf implementing format-based scanning a la scanf() in C.
- Module Arg: added alternate entry point Arg.parse_argv.
- Modules Char, Int32, Int64, Nativeint, String: added type "t" and function
  "compare" so that these modules can be used directly with e.g. Set.Make.
- Module Digest: fixed issue with Digest.file on large files (>= 1Gb);
    added Digest.to_hex.
- Module Filename: added Filename.open_temp_file to atomically create and
    open the temp file; improved security of Filename.temp_file.
- Module Genlex: allow _ as first character of an identifier.
- Module Lazy: more efficient implementation.
- Module Lexing: improved performances for very large tokens.
- Module List: faster implementation of sorting functions.
- Module Printf:
    added %S and %C formats (quoted, escaped strings and characters);
    added kprintf (calls user-specified continuation on formatted string).
- Module Queue: faster implementation (courtesy of François Pottier).
- Module Random: added Random.bool.
- Module Stack: added Stack.is_empty.
- Module Pervasives:
    added sub-module LargeFile to support files larger than 1Gb
      (file offsets are int64 rather than int);
    opening in "append" mode automatically sets "write" mode;
    files are now opened in close-on-exec mode;
    string_of_float distinguishes its output from a plain integer;
    faster implementation of input_line for long lines.
- Module Sys:
     added Sys.ocaml_version containing the OCaml version number;
     added Sys.executable_name containing the (exact) path of the
       file being executable;
     Sys.argv.(0) is now unchanged w.r.t. what was provided as 0-th argument
       by the shell.
- Module Weak: added weak hash tables.

Other libraries:
- Bigarray:
    support for bigarrays of complex numbers;
    added functions Genarray.dims,
      {Genarray,Array1,Array2,Array3}.{kind,layout}.
- Dynlink: fixed bug with loading of mixed-mode Caml/C libraries.
- LablTK:
    now supports also the CamlTK API (no labels);
    support for Activate and Deactivate events;
    support for virtual events;
    added UTF conversion;
    export the tcl interpreter as caml value, to avoid DLL dependencies.
- Unix:
    added sub-module LargeFile to support files larger than 1Gb
      (file offsets are int64 rather than int);
    added POSIX opening flags (O_NOCTTY, O_*SYNC);
    use reentrant functions for gethostbyname and gethostbyaddr when available;
    fixed bug in Unix.close_process and Unix.close_process_full;
    removed some overhead in Unix.select.

Tools:
- ocamldoc (the documentation generator) is now part of the distribution.
- Debugger: now supports the option -I +dir.
- ocamllex: supports the same identifiers as ocamlc; warns for
  bad \ escapes in strings and characters.
- ocamlbrowser:
    recenter the module boxes when showing a cross-reference;
    include the current directory in the ocaml path.

Windows port:
- Can now compile with Mingw (the GNU compilers without the Cygwin
  runtime library) in addition to MSVC.
- Toplevel GUI: wrong filenames were given to #use and #load commands;
  read_line() was buggy for short lines (2 characters or less).
- OCamlBrowser: now fully functional.
- Graphics library: fixed several bugs in event handling.
- Threads library: fixed preemption bug.
- Unix library: better handling of the underlying differences between
  sockets and regular file descriptors;
  added Unix.lockf and a better Unix.rename (thanks to Tracy Camp).
- LablTk library: fixed a bug in Fileinput


Objective Caml 3.04 (13 Dec 2001):
----------------------------------

Type-checker:
- Allowed coercing self to the type of the current class, avoiding
  an obscure error message about "Self type cannot be unified..."

Both compilers:
- Use OCAMLLIB environment variable to find standard library, falls
  back on CAMLLIB if not defined.
- Report out-of-range ASCII escapes in character or string literals
  such as "\256".

Byte-code compiler:
- The -use-runtime and -make-runtime flags are back by popular demand
  (same behavior as in 3.02).
- Dynamic loading (of the C part of mixed Caml/C libraries): arrange that
  linking in -custom mode uses the static libraries for the C parts,
  not the shared libraries, for maximal robustness and compatibility with
  3.02.

Native-code compiler:
- Fixed bug in link-time consistency checking.

Tools:
- ocamlyacc: added parser debugging support (set OCAMLRUNPARAM=p to get
  a trace of the pushdown automaton actions).
- ocamlcp: was broken in 3.03 (Sys_error), fixed.

Run-time system:
- More work on dynamic loading of the C part of mixed Caml/C libraries.
- On uncaught exception, flush output channels before printing exception
  message and backtrace.
- Corrected several errors in exception backtraces.

Standard library:
- Pervasives: integer division and modulus are now fully specified
  on negative arguments (with round-towards-zero semantics).
- Pervasives.float_of_string: now raises Failure on ill-formed input.
- Pervasives: added useful float constants max_float, min_float, epsilon_float.
- printf functions in Printf and Format: added % formats for int32, nativeint,
  int64; "*" in width and precision specifications now supported
  (contributed by Thorsten Ohl).
- Added Hashtbl.copy, Stack.copy.
- Hashtbl: revised resizing strategy to avoid quadratic behavior
  on Hashtbl.add.
- New module MoreLabels providing labelized versions of modules
  Hashtbl, Map and Set.
- Pervasives.output_value and Marshal.to_* : improved hashing strategy
  for internal data structures, avoid excessive slowness on
  quasi-linearly-allocated inputs.

Other libraries:
- Num: fixed bug in big integer exponentiation (Big_int.power_*).

Windows port:
- New GUI for interactive toplevel (Jacob Navia).
- The Graphics library is now available for stand-alone executables
  (Jacob Navia).
- Unix library: improved reporting of system error codes.
- Fixed error in "globbing" of * and ? patterns on command line.

Emacs mode: small fixes; special color highlighting for ocamldoc comments.

License: added special exception to the LGPL'ed code (libraries and
  runtime system) allowing unrestricted linking, whether static or dynamic.


Objective Caml 3.03 ALPHA (12 Oct 2001):
----------------------------------------

Language:
- Removed built-in syntactic sugar for streams and stream patterns
  [< ... >], now supported via CamlP4, which is now included in the
  distribution.
- Switched the default behaviour to labels mode (labels are compulsory),
  but allows omitting labels when a function application is complete.
  -nolabels mode is available but deprecated for programming.
  (See also scrapelabels and addlabels tools below.)
- Removed all labels in the standard libraries, except labltk.
  Labelized versions are kept for ArrayLabels, ListLabels, StringLabels
  and UnixLabels. "open StdLabels" gives access to the first three.
- Extended polymorphic variant type syntax, allowing union types and
  row abbreviations for both sub- and super-types. #t deprecated in types.
- See the Upgrading file for how to adapt to all the changes above.

Type-checker:
- Fixed obscure bug in module typing causing the type-checker to loop
  on signatures of the form
        module type M
        module A: sig module type T = sig module T: M end end
        module B: A.T
- Improved efficiency of module type-checking via lazy computation of
  certain signature summary information.
- An empty polymorphic variant type is now an error.

Both compilers:
- Fixed wrong code generated for "struct include M ... end" when M
  contains one or several "external" declarations.

Byte-code compiler:
- Protect against VM stack overflow caused by module initialization code
  with many local variables.
- Support for dynamic loading of the C part of mixed Caml/C libraries.
- Removed the -use-runtime and -make-runtime flags, obsoleted by dynamic
  loading of C libraries.

Native-code compiler:
- Attempt to recover gracefully from system stack overflow.  Currently
  works on x86 under Linux and BSD.
- Alpha: work around "as" bug in Tru64 5.1.

Toplevel environment:
- Revised printing of inferred types and evaluation results
  so that an external printer (e.g. Camlp4's) can be hooked in.

Tools:
- The CamlP4 pre-processor-pretty-printer is now included in the standard
  distribution.
- New tool ocamlmklib to help build mixed Caml/C libraries.
- New tool scrapelabels and addlabels, to either remove (non-optional)
  labels in interfaces, or automatically add them in the definitions.
  They provide easy transition from classic mode ocaml 3.02 sources,
  depending on whether you want to keep labels or not.
- ocamldep: added -pp option to handle preprocessed source files.

Run-time system:
- Support for dynamic loading of the C part of mixed Caml/C libraries.
  Currently works under Linux, FreeBSD, Windows, Tru64, Solaris and Irix.
- Implemented registration of global C roots with a skip list,
  runs much faster when there are many global C roots.
- Autoconfiguration script: fixed wrong detection of Mac OS X; problem
  with the Sparc, gcc 3.0, and float alignment fixed.

Standard library:
- Added Pervasives.flush_all to flush all opened output channels.

Other libraries:
- All libraries revised to allow dynamic loading of the C part.
- Graphics under X Windows: revised event handling, should no longer lose
    mouse events between two calls to wait_next_event(); wait_next_event()
    now interruptible by signals.
- Bigarrays: fixed bug in marshaling of big arrays.

Windows port:
- Fixed broken Unix.{get,set}sockopt*



Objective Caml 3.02 (30 Jul 2001):
----------------------------------

Both compilers:
- Fixed embarrassing bug in pattern-matching compilation
  (affected or-patterns containing variable bindings).
- More optimizations in pattern-matching compilation.

Byte-code compiler:
- Protect against VM stack overflow caused by functions with many local
  variables.

Native-code compiler:
- Removed re-sharing of string literals, causes too many surprises with
  in-place string modifications.
- Corrected wrong compilation of toplevel "include" statements.
- Fixed bug in runtime function "callbackN_exn".
- Signal handlers receive the conventional signal number as argument
  instead of the system signal number (same behavior as with the
  bytecode compiler).
- ARM port: fixed issue with immediate operand overflow in large functions.

Toplevel environment:
- User-definer printers (for #install_printer) now receive as first argument
  the pretty-printer formatter where to print their second argument.
  Old printers (with only one argument) still supported for backward
  compatibility.

Standard library:
- Module Hashtbl: added Hashtbl.fold.

Other libraries:
- Dynlink: better error reporting in add_interfaces for missing .cmi files.
- Graphics: added more drawing functions (multiple points, polygons,
    multiple lines, splines).
- Bytecode threads: the module Unix is now thread-safe, ThreadUnix is
    deprecated.  Unix.exec* now resets standard descriptors to blocking mode.
- Native threads: fixed a context-switch-during-GC problem causing
    certain C runtime functions to fail, most notably input_value.
- Unix.inet_addr_of_string: call inet_aton() when available so as to
    handle correctly the address 255.255.255.255.
- Unix: added more getsockopt and setsockopt functions to get/set
    options that have values other than booleans.
- Num: added documentation for the Big_int module.

Tools:
- ocamldep: fixed wrong dependency issue with nested modules.

Run-time system:
- Removed floating-point error at start-up on some non-IEEE platforms
  (e.g. FreeBSD prior to 4.0R).
- Stack backtrace mechanism now works for threads that terminate on
  an uncaught exception.

Auto-configuration:
- Updated config.guess and config.sub scripts, should recognize a greater
  number of recent platform.

Windows port:
- Fixed broken Unix.waitpid.  Unix.file_descr can now be compared or hashed.
- Toplevel application: issue with spaces in name of stdlib directory fixed.

MacOS 9 port:
- Removed the last traces of support for 68k


Objective Caml 3.01 (09 Mar 2001):
----------------------------------

New language features:
- Variables are allowed in "or" patterns, e.g.
     match l with [t] | [_;t] -> ... t ...
- "include <structure expression>" to re-export all components of a
  structure inside another structure.
- Variance annotation on parameters of type declarations, e.g.
    type (+'a,-'b,'c) t (covariant in 'a, contravariant in 'b, invariant in 'c)

New ports:
- Intel IA64/Itanium under Linux (including the native-code compiler).
- Cygwin under MS Windows.  This port is an alternative to the earlier
  Windows port of OCaml, which relied on MS compilers; the Cygwin
  Windows port does not need MS Visual C++ nor MASM, runs faster
  in bytecode, and has a better implementation of the Unix library,
  but currently lacks threads and COM component support.

Type-checking:
- Relaxed "monomorphic restriction" on type constructors in a
  mutually-recursive type definition, e.g. the following is again allowed
    type u = C of int t | D of string t and 'a t = ...
- Fixed name-capture bug in "include SIG" and "SIG with ..." constructs.
- Improved implicit subtypes built by (... :> ty), closer to intuition.
- Several bug fixes in type-checking of variants.
- Typing of polymorphic variants is more restrictive:
   do not allow conjunctive types inside the same pattern matching.
   a type has either an upper bound, or all its tags are in the lower bound.
  This may break some programs (this breaks lablgl-0.94).

Both compilers:
- Revised compilation of pattern matching.
- Option -I +<subdir> to search a subdirectory <subdir> of the standard
  library directory (i.e. write "ocamlc -I +labltk" instead of
  "ocamlc -I /usr/local/lib/ocaml/labltk").
- Option -warn-error to turn warnings into errors.
- Option -where to print the location of the standard library directory.
- Assertions are now type-checked even if the -noassert option is given,
  thus -noassert can no longer change the types of modules.

Bytecode compiler and bytecode interpreter:
- Print stack backtrace when a program aborts due to an uncaught exception
  (requires compilation with -g and running with ocamlrun -b or
   OCAMLRUNPARAM="b=1").

Native-code compiler:
- Better unboxing optimizations on the int32, int64, and nativeint types.
- Tail recursion preserved for functions having more parameters than
  available registers (but tail calls to other functions are still
  turned off if parameters do not fit entirely in registers).
- Fixed name-capture bug in function inlining.
- Improved spilling/reloading strategy for conditionals.
- IA32, Alpha: better alignment of branch targets.
- Removed spurious dependency on the -lcurses library.

Toplevel environment:
- Revised handling of top-level value definitions, allows reclamation
  of definitions that are shadowed by later definitions with the same names.
  (E.g. "let x = <big list>;; let x = 1;;" allows <big list> to be reclaimed.)
- Revised the tracing facility so that for standard library functions,
  only calls from user code are traced, not calls from the system.
- Added a "*" prompt when within a comment.

Runtime system:
- Fixed portability issue on bcopy() vs memmove(), affecting Linux RedHat 7.0
  in particular.
- Structural comparisons (=, <>, <, <=, >, >=, compare) reimplemented
  so as to avoid overflowing the C stack.
- Input/output functions: arrange so that reads and writes on closed
  in_channel or out_channel raise Sys_error immediately.

Standard library:
- Module Gc: changed some counters to float in order to avoid overflow;
    added alarms
- Module Hashtbl: added Hashtbl.replace.
- Module Int64: added bits_of_float, float_of_bits (access to IEEE 754
    representation of floats).
- Module List:  List.partition now tail-rec;
    improved memory behavior of List.stable_sort.
- Module Nativeint: added Nativeint.size (number of bits in a nativeint).
- Module Obj: fixed incorrect resizing of float arrays in Obj.resize.
- Module Pervasives: added float constants "infinity", "neg_infinity", "nan";
    added a "classify_float" function to test a float for NaN, infinity, etc.
- Pervasives.input_value: fixed bug affecting shared custom objects.
- Pervasives.output_value: fixed size bug affecting "int64" values.
- Pervasives.int_of_string, {Int32,Int64,Nativeint}.of_string:
  fixed bug causing bad digits to be accepted without error.
- Module Random: added get_state and set_state to checkpoint the generator.
- Module Sys: signal handling functions are passed the system-independent
  signal number rather than the raw system signal number whenever possible.
- Module Weak: added Weak.get_copy.

Other libraries:
- Bigarray: added Bigarray.reshape to take a view of the elements of a
  bigarray with different dimensions or number of dimensions;
  fixed bug causing "get" operations to be unavailable in custom
  toplevels including Bigarray.
- Dynlink: raise an error instead of crashing when the loaded module
  refers to the not-yet-initialized module performing a dynlink operation.
- Bytecode threads: added a thread-safe version of the Marshal module;
    fixed a rare GC bug in the thread scheduler.
- POSIX threads: fixed compilation problem with threads.cmxa.
- Both thread libraries: better tail-recursion in Event.sync.
- Num library: fixed bug in square roots (Nat.sqrt_nat, Big_int.sqrt_big_int).

Tools:
- ocamldep: fixed missing dependencies on labels of record patterns and
    record construction operations

Win32 port:
- Unix.waitpid now implements the WNOHANG option.

Mac OS ports:
- Mac OS X public beta is supported.
- Int64.format works on Mac OS 8/9.


Objective Caml 3.00 (25 Apr 2000):
----------------------------------

Language:
- OCaml/OLabl merger:
  * Support for labeled and optional arguments for functions and classes.
  * Support for variant types (sum types compared by structure).
  See tutorial (chapter 2 of the OCaml manual) for more information.
- Syntactic change: "?" in stream error handlers changed to "??".
- Added exception renaming in structures (exception E = F).
- (OCaml 2.99/OLabl users only) Label syntax changed to preserve
  backward compatibility with 2.0x (labeled function application
  is f ~lbl:arg instead of f lbl:arg).  A tool is provided to help
  convert labelized programs to OCaml 3.00.

Both compilers:
- Option -labels to select commuting label mode (labels are mandatory,
  but labeled arguments can be passed in a different order than in
  the definition of the function; in default mode, labels may be omitted,
  but argument reordering is only allowed for optional arguments).
- Libraries (.cma and .cmxa files) now "remember" C libraries given
  at library construction time, and add them back at link time.
  Allows linking with e.g. just unix.cma instead of
  unix.cma -custom -cclib -lunix
- Revised printing of error messages, now use Format.fprintf; no visible
  difference for users, but could facilitate internationalization later.
- Fixed bug in unboxing of records containing only floats.
- Fixed typing bug involving applicative functors as components of modules.
- Better error message for inconsistencies between compiled interfaces.

Bytecode compiler:
- New "modular" format for bytecode executables; no visible differences
  for users, but will facilitate further extensions later.
- Fixed problems in signal handling.

Native-code compiler:
- Profiling support on x86 under FreeBSD
- Open-coding and unboxing optimizations for the new integer types
  int32, int64, nativeint, and for bigarrays.
- Fixed instruction selection bug with "raise" appearing in arguments
  of strict operators, e.g. "1 + raise E".
- Better error message when linking incomplete/incorrectly ordered set
  of .cmx files.
- Optimized scanning of global roots during GC, can reduce total running
  time by up to 8% on GC-intensive programs.

Interactive toplevel:
- Better printing of exceptions, including arguments, when possible.
- Fixed rare GC bug occurring during interpretation of scripts.
- Added consistency checks between interfaces and implementations
  during #load.

Run-time system:
- Added support for "custom" heap blocks (heap blocks carrying
  C functions for finalization, comparison, hashing, serialization
  and deserialization).
- Support for finalisation functions written in Caml.

Standard library:
- New modules Int32, Int64, Nativeint for 32-bit, 64-bit and
  platform-native integers
- Module Array: added Array.sort, Array.stable_sort.
- Module Gc: added Gc.finalise to attach Caml finalisation functions to
  arbitrary heap-allocated data.
- Module Hashtbl: do not bomb when resizing very large table.
- Module Lazy: raise Lazy.Undefined when a lazy evaluation needs itself.
- Module List: added List.sort, List.stable_sort; fixed bug in List.rev_map2.
- Module Map: added mapi (iteration with key and data).
- Module Set: added iterators for_all, exists, filter, partition.
- Module Sort: still here but deprecated in favor of new sorting functions
  in Array and List.
- Module Stack: added Stack.top
- Module String: fixed boundary condition on String.rindex_from
- Added labels on function arguments where appropriate.

New libraries and tools:
- ocamlbrowser: graphical browser for OCaml sources and compiled interfaces,
  supports cross-referencing, editing, running the toplevel.
- LablTK: GUI toolkit based on TK, using labeled and optional arguments,
  easier to use than CamlTK.
- Bigarray: large, multi-dimensional numerical arrays, facilitate
  interfacing with C/Fortran numerical code, efficient support for
  advanced array operations such as slicing and memory-mapping of files.

Other libraries:
- Bytecode threads: timer-based preemption was broken, works back again;
  fixed bug in Pervasives.input_line; exported Thread.yield.
- System threads: several GC / reentrancy bugs fixed in buffered I/O
  and Unix I/O; revised Thread.join implementation for strict POSIX
  conformance; exported Thread.yield.
- Graphics: added support for double buffering; added, current_x, current_y,
  rmoveto, rlineto, and draw_rect.
- Num: fixed bug in Num.float_of_num.
- Str: worked around potential symbol conflicts with C standard library.
- Dbm: fixed bug with Dbm.iter on empty database.

New or updated ports:
- Alpha/Digital Unix: lifted 256M limitation on total memory space
  induced by -taso
- Port to AIX 4.3 on PowerPC
- Port to HPUX 10 on HPPA
- Deprecated 680x0 / SunOS port

Macintosh port:
- Implemented the Unix and Thread libraries.
- The toplevel application does not work on 68k Macintoshes; maybe
  later if there's a demand.
- Added a new tool, ocamlmkappli, to build an application from a
  program written in O'Caml.


Objective Caml 2.04 (26 Nov 1999):
----------------------------------

- C interface: corrected inconsistent change in the CAMLparam* macros.
- Fixed internal error in ocamlc -g.
- Fixed type-checking of "S with ...", where S is a module type name
  abbreviating another module type name.
- ocamldep: fixed stdout/stderr mismatch after failing on one file.
- Random.self_init more random.
- Windows port:
  - Toplevel application: fixed spurious crash on exit.
  - Native-code compiler: fixed bug in assembling certain
    floating-point constants (masm doesn't grok 2e5, wants 2.0e5).

Objective Caml 2.03 (19 Nov 1999):
----------------------------------

New ports:
- Ported to BeOS / Intel x86 (bytecode and native-code).
- BSD / Intel x86 port now supports both a.out and ELF binary formats.
- Added support for {Net,Open}BSD / Alpha.
- Revamped Rhapsody port, now works on MacOS X server.

Syntax:
- Warning for "(*)" and "*)" outside comment.
- Removed "#line LINENO", too ambiguous with a method invocation;
  the equivalent "# LINENO" is still supported.

Typing:
- When an incomplete pattern-matching is detected, report also a
  value or value template that is not covered by the cases of
  the pattern-matching.
- Several bugs in class type matching and in type error reporting fixed.
- Added an option -rectypes to support general recursive types,
  not just those involving object types.

Bytecode compiler:
- Minor cleanups in the bytecode emitter.
- Do not remove "let x = y" bindings in -g mode; makes it easier to
  debug the code.

Native-code compiler:
- Fixed bug in grouping of allocations performed in the same basic block.
- Fixed bug in constant propagation involving expressions containing
  side-effects.
- Fixed incorrect code generation for "for" loops whose upper bound is
  a reference assigned inside the loop.
- MIPS code generator: work around a bug in the IRIX 6 assembler.

Toplevel:
- Fixed incorrect redirection of standard formatter to stderr
  while executing toplevel scripts.

Standard library:
- Added List.rev_map, List.rev_map2.
- Documentation of List functions now says which functions are
  tail-rec, and how much stack space is needed for non-tailrec functions.
- Wrong type for Printf.bprintf fixed.
- Fixed weird behavior of Printf.sprintf and Printf.bprintf in case of
  partial applications.
- Added Random.self_init, which initializes the PRNG from the system date.
- Sort.array: serious bugs fixed.
- Stream.count: fixed incorrect behavior with ocamlopt.

Run-time system and external interface:
- Fixed weird behavior of signal handlers w.r.t. signal masks and exceptions
  raised from the signal handler.
- Fixed bug in the callback*_exn() functions.

Debugger:
- Fixed wrong printing of float record fields and elements of float arrays.
- Supports identifiers starting with '_'.

Profiler:
- Handles .mli files, so ocamlcp can be used to replace ocamlc (e.g. in a
  makefile).
- Now works on programs that use stream expressions and stream parsers.

Other libraries:
- Graphics: under X11, treat all mouse buttons equally; fixed problem
  with current font reverting to the default font when the graphics
  window is resized.
- Str: fixed reentrancy bugs in Str.replace and Str.full_split.
- Bytecode threads: set standard I/O descriptors to non-blocking mode.
- OS threads: revised implementation of Thread.wait_signal.
- All threads: added Event.wrap_abort, Event.choose [].
- Unix.localtime, Unix.gmtime: check for errors.
- Unix.create_process: now supports arbitrary redirections of std descriptors.
- Added Unix.open_process_full.
- Implemented Unix.chmod under Windows.
- Big_int.square_big_int now gives the proper sign to its result.

Others:
- ocamldep: don't stop at first error, skip to next file.
- Emacs mode: updated with Garrigue and Zimmerman's snapshot of 1999/10/18.
- configure script: added -prefix option.
- Windows toplevel application: fixed problem with graphics library
  not loading properly.


Objective Caml 2.02 (04 Mar 1999):
----------------------------------

* Type system:
  - Check that all components of a signature have unique names.
  - Fixed bug in signature matching involving a type component and
    a module component, both sharing an abstract type.
  - Bug involving recursive classes constrained by a class type fixed.
  - Fixed bugs in printing class types and in printing unification errors.

* Compilation:
  - Changed compilation scheme for "{r with lbl = e}" when r has many fields
    so as to avoid code size explosion.

* Native-code compiler:
  - Better constant propagation in boolean expressions and in conditionals.
  - Removal of unused arguments during function inlining.
  - Eliminated redundant tagging/untagging in bit shifts.
  - Static allocation of closures for functions without free variables,
    reduces the size of initialization code.
  - Revised compilation scheme for definitions at top level of compilation
    units, so that top level functions have no free variables.
  - Coalesced multiple allocations of heap blocks inside one expression
    (e.g. x :: y :: z allocates the two conses in one step).
  - Ix86: better handling of large integer constants in instruction selection.
  - MIPS: fixed wrong asm generated for String.length "literal".

* Standard library:
  - Added the "ignore" primitive function, which just throws away its
    argument and returns "()".  It allows to write
    "ignore(f x); y" if "f x" doesn't have type unit and you don't
    want the warning caused by "f x; y".
  - Added the "Buffer" module (extensible string buffers).
  - Module Format: added formatting to buffers and to strings.
  - Added "mem" functions (membership test) to Hashtbl and Map.
  - Module List: added find, filter, partition.
    Renamed remove and removeq to remove_assoc and remove_assq.
  - Module Marshal: fixed bug in marshaling functions when passed functional
    values defined by mutual recursion with other functions.
  - Module Printf: added Printf.bprintf (print to extensible buffer);
    added %i format as synonymous for %d (as per the docs).
  - Module Sort: added Sort.array (Quicksort).

* Runtime system:
  - New callback functions for callbacks with arbitrary many arguments
    and for catching Caml exceptions escaping from a callback.

* The ocamldep dependency generator: now performs full parsing of the
    sources, taking into account the scope of module bindings.

* The ocamlyacc parser generator: fixed sentinel error causing wrong
    tables to be generated in some cases.

* The str library:
  - Added split_delim, full_split as variants of split that control
    more precisely what happens to delimiters.
  - Added replace_matched for separate matching and replacement operations.

* The graphics library:
  - Bypass color lookup for 16 bpp and 32 bpp direct-color displays.
  - Larger color cache.

* The thread library:
  - Bytecode threads: more clever use of non-blocking I/O, makes I/O
    operations faster.
  - POSIX threads: gcc-ism removed, should now compile on any ANSI C compiler.
  - Both: avoid memory leak in the Event module when a communication
    offer is never selected.

* The Unix library:
  - Fixed inversion of ctime and mtime in Unix.stat, Unix.fstat, Unix.lstat.
  - Unix.establish_connection: properly reclaim socket if connect fails.

* The DBM library: no longer crashes when calling Dbm.close twice.

* Emacs mode:
  - Updated with Garrigue and Zimmerman's latest version.
  - Now include an "ocamltags" script for using etags on OCaml sources.

* Win32 port:
  - Fixed end-of-line bug in ocamlcp causing problems with generated sources.


Objective Caml 2.01 (09 Dec 1998):
----------------------------------

* Typing:
  - Added warning for expressions of the form "a; b" where a does not have
    type "unit"; catches silly mistake such as
    "record.lbl = newval; ..." instead of "record.lbl <- newval; ...".
  - Typing bug in "let module" fixed.

* Compilation:
  - Fixed bug in compilation of recursive and mutually recursive classes.
  - Option -w to turn specific warnings on/off.
  - Option -cc to choose the C compiler used with ocamlc -custom and ocamlopt.

* Bytecode compiler and bytecode interpreter:
  - Intel x86: removed asm declaration causing "fixed or forbidden register
    spilled" error with egcs and gcc 2.8 (but not with gcc 2.7, go figure).
  - Revised handling of debugging information, allows faster linking with -g.

* Native-code compiler:
  - Fixed bugs in integer constant propagation.
  - Out-of-bound accesses in array and strings now raise an Invalid_argument
    exception (like the bytecode system) instead of stopping the program.
  - Corrected scheduling of bound checks.
  - Port to the StrongARM under Linux (e.g. Corel Netwinder).
  - I386: fixed bug in profiled code (ocamlopt -p).
  - Mips: switched to -n32 model under IRIX; dropped the Ultrix port.
  - Sparc: simplified the addressing modes, allows for better scheduling.
  - Fixed calling convention bug for Pervasives.modf.

* Toplevel:
  - #trace works again.
  - ocamlmktop: use matching ocamlc, not any ocamlc from the search path.

* Memory management:
  - Fixed bug in heap expansion that could cause the GC to loop.

* C interface:
  - New macros CAMLparam... and CAMLlocal... to simplify the handling
    of local roots in C code.
  - Simplified procedure for allocating and filling Caml blocks from C.
  - Declaration of string_length in <caml/mlvalues.h>.

* Standard library:
  - Module Format: added {get,set}_all_formatter_output_functions,
    formatter_of_out_channel, and the control sequence @<n> in printf.
  - Module List: added mem_assoc, mem_assq, remove, removeq.
  - Module Pervasives: added float_of_int (synonymous for float),
    int_of_float (truncate), int_of_char (Char.code), char_of_int (Char.chr),
    bool_of_string.
  - Module String: added contains, contains_from, rcontains_from.

* Unix library:
  - Unix.lockf: added F_RLOCK, F_TRLOCK; use POSIX locks whenever available.
  - Unix.tc{get,set}attr: added non-standard speeds 57600, 115200, 230400.
  - Unix.chroot: added.

* Threads:
  - Bytecode threads: improved speed of I/O scheduling.
  - Native threads: fixed a bug involving signals and exceptions
    generated from C.

* The "str" library:
  - Added Str.string_partial_match.
  - Bumped size of internal stack.

* ocamlyacc: emit correct '# lineno' directive for prelude part of .mly file.

* Emacs editing mode: updated with Jacques Garrigue's newest code.

* Windows port:
  - Added support for the "-cclib -lfoo" option (instead of
     -cclib /full/path/libfoo.lib as before).
  - Threads: fixed a bug at initialization time.

* Macintosh port: source code for Macintosh application merged in.


Objective Caml 2.00 (19 Aug 1998):
----------------------------------

* Language:
  - New class language.  See http://caml.inria.fr/ocaml/refman/
    for a tutorial (chapter 2) and for the reference manual (section 4.9).
  - Local module definitions "let module X = <module-expr> in <expr>".
  - Record copying with update "{r with lbl1 = expr1; ...}".
  - Array patterns "[|pat1; ...;patN|]" in pattern-matchings.
  - New reserved keywords: "object", "initializer".
  - No longer reserved: "closed", "protected".

* Bytecode compiler:
  - Use the same compact memory representations for float arrays, float
    records and recursive closures as the native-code compiler.
  - More type-dependent optimizations.
  - Added the -use_runtime and -make_runtime flags to build separately
    and reuse afterwards custom runtime systems
    (inspired by Fabrice Le Fessant's patch).

* Native-code compiler:
  - Cross-module constant propagation of integer constants.
  - More type-dependent optimizations.
  - More compact code generated for "let rec" over data structures.
  - Better code generated for "for" loops (test at bottom of code).
  - More aggressive scheduling of stores.
  - Added -p option for time profiling with gprof
    (fully supported on Intel x86/Linux and Alpha/Digital Unix only)
    (inspired by Aleksey Nogin's patch).
  - A case of bad spilling with high register pressure fixed.
  - Fixed GC bug when GC called from C without active Caml code.
  - Alpha: $gp handling revised to follow Alpha's standard conventions,
    allow running "atom" and "pixie" on ocamlopt-generated binaries.
  - Intel x86: use movzbl and movsbl systematically to load 8-bit and 16-bit
    quantities, no more hacks with partial registers (better for the
    Pentium Pro, worse for the Pentium).
  - PowerPC: more aggressive scheduling of return address reloading.
  - Sparc: scheduling bug related to register pairs fixed.

* Runtime system:
  - Better printing of uncaught exceptions (print a fully qualified
    name whenever possible).

* New ports:
  - Cray T3E (bytecode only) (in collaboration with CEA).
  - PowerMac under Rhapsody.
  - SparcStations under Linux.

* Standard library:
  - Added set_binary_mode_in and set_binary_mode_out in Pervasives
    to toggle open channels between text and binary modes.
  - output_value and input_value check that the given channel is in
    binary mode.
  - input_value no longer fails on very large marshalled data (> 16 Mbytes).
  - Module Arg: added option Rest.
  - Module Filename: temp_file no longer loops if temp dir doesn't exist.
  - Module List: added rev_append (tail-rec alternative to @).
  - Module Set: tell the truth about "elements" returning a sorted list;
    added min_elt, max_elt, singleton.
  - Module Sys: added Sys.time for simple measuring of CPU time.

* ocamllex:
  - Check for overflow when generating the tables for the automaton.
  - Error messages in generated .ml file now point to .mll source.
  - Added "let <id> = <regexp>" to name regular expressions
    (inspired by Christian Lindig).

* ocamlyacc:
  - Better error recovery in presence of EOF tokens.
  - Error messages in generated .ml file now point to .mly source.
  - Generated .ml file now type-safe even without the generated .mli file.

* The Unix library:
  - Use float instead of int to represent Unix times (number of seconds
    from the epoch).  This fixes a year 2005 problem on 32-bit platforms.
    Functions affected: stat, lstat, fstat, time, gmtime, localtime,
    mktime, utimes.
  - Added putenv.
  - Better handling of "unknown" error codes (EUNKNOWNERR).
  - Fixed endianness bug in getservbyport.
  - win32unix (the Win32 implementation of the Unix library) now has
    the same interface as the unix implementation, this allows exchange
    of compiled .cmo and .cmi files between Unix and Win32.

* The thread libraries:
  - Bytecode threads: bug with escaping exceptions fixed.
  - System threads (POSIX, Win32): malloc/free bug fixed; signal bug fixed.
  - Both: added Thread.wait_signal to wait synchronously for signals.

* The graph library: bigger color cache.

* The str library: added Str.quote, Str.regexp_string,
  Str.regexp_string_case_fold.

* Emacs mode:
  - Fixed bug with paragraph fill.
  - Fixed bug with next-error under Emacs 20.


Objective Caml 1.07 (11 Dec 1997):
----------------------------------

* Native-code compiler:
  - Revised interface between generated code and GC, fixes serious GC
    problems with signals and native threads.
  - Added "-thread" option for compatibility with ocamlc.

* Debugger: correctly print instance variables of objects.

* Run-time system: ported to OpenBSD.

* Standard library: fixed wrong interface for Marshal.to_buffer and
  Obj.unmarshal.

* Num library: added Intel x86 optimized asm code (courtesy of
  Bernard Serpette).

* Thread libraries:
  - Native threads: fixed GC bugs and installation procedure.
  - Bytecode threads: fixed problem with "Marshal" module.
  - Both: added Event.always.

* MS Windows port: better handling of long command lines in Sys.command

Objective Caml 1.06 (18 Nov 1997):
----------------------------------

* Language:
  - Added two new keywords: "assert" (check assertion) and "lazy"
    (delay evaluation).
  - Allow identifiers to start with "_" (such identifiers are treated
    as lowercase idents).

* Objects:
  - Added "protected" methods (visible only from subclasses, can be hidden
    in class type declared in module signature).
  - Objects can be compared using generic comparison functions.
  - Fixed compilation of partial application of object constructors.

* Type system:
  - Occur-check now more strict (all recursions must traverse an object).
  - A few bugs fixed.

* Run-time system:
  - A heap compactor was implemented, so long-running programs can now
    fight fragmentation.
  - The meaning of the "space_overhead" parameter has changed.
  - The macros Push_roots and Pop_roots are superseded by Begin_roots* and
    End_roots.
  - Bytecode executable includes list of primitives used, avoids crashes
    on version mismatch.
  - Reduced startup overhead for marshalling, much faster marshalling of
    small objects.
  - New exception Stack_overflow distinct from Out_of_memory.
  - Maximum stack size configurable.
  - I/O revised for compatibility with compactor and with native threads.
  - All C code ANSIfied (new-style function declarations, etc).
  - Threaded code work on all 64-bit processors, not just Alpha/Digital Unix.
  - Better printing of uncaught exceptions.

* Both compilers:
  - Parsing: more detailed reporting of syntax errors (e.g. shows
    unmatched opening parenthesis on missing closing parenthesis).
  - Check consistency between interfaces (.cmi).
  - Revised rules for determining dependencies between modules.
  - Options "-verbose" for printing calls to C compiler, "-noassert"
    for turning assertion checks off.

* Native-code compiler:
  - Machine-dependent parts rewritten using inheritance instead of
    parameterized modules.
  - GC bug in value let rec fixed.
  - Port to Linux/Alpha.
  - Sparc: cleaned up use of %g registers, now compatible with Solaris threads.

* Top-level interactive system:
  - Can execute Caml script files given on command line.
  - Reads commands from ./.ocamlinit on startup.
  - Now thread-compatible.

* Standard library:
  - New library module: Lazy (delayed computations).
  - New library module: Marshal.  Allows marshalling to strings and
    transmission of closures between identical programs (SPMD parallelism).
  - Filename: "is_absolute" is superseded by "is_implicit" and "is_relative".
    To adapt old programs, change "is_absolute x" to "not (is_implicit x)"
    (but the new "is_relative" is NOT the opposite of the old "is_absolute").
  - Array, Hashtbl, List, Map, Queue, Set, Stack, Stream:
    the "iter" functions now take as argument a unit-returning function.
  - Format: added "printf" interface to the formatter (see the documentation).
    Revised behaviour of simple boxes: no more than one new line is output
    when consecutive break hints should lead to multiple line breaks.
  - Stream: revised implementation, renamed Parse_failure to Failure and
    Parse_error to Error (don't you love gratuitous changes?).
  - String: added index, rindex, index_from, rindex_from.
  - Array: added mapi, iteri, fold_left, fold_right, init.
  - Added Map.map, Set.subset, Printexc.to_string.

* ocamllex: lexers generated by ocamllex can now handle all characters,
  including '\000'.

* ocamlyacc: fixed bug with function closures returned by parser rules.

* Debugger:
  - Revised generation of events.
  - Break on function entrance.
  - New commands start/previous.
  - The command loadprinter now try to recursively load required
    modules.
  - Numerous small fixes.

* External libraries:
  - systhreads: can now use POSIX threads; POSIX and Win32 threads are
    now supported by the native-code compiler.
  - dbm and graph: work in native code.
  - num: fixed bug in Nat.nat_of_string.
  - str: fixed deallocation bug with case folding.
  - win32unix: use Win32 handles instead of (buggy) VC++ emulation of Unix
    file handles; added gettimeofday.

* Emacs editing mode and debugger interface updated to July '97 version.

Objective Caml 1.05 (21 Mar 1997):
----------------------------------

* Typing: fixed several bugs causing spurious type errors.

* Native-code compiler: fixed instruction selection bug causing GC to
see ill-formed pointers; fixed callbacks to support invocation from a
main program in C.

* Standard library: fixed String.lowercase; Weak now resists integers.

* Toplevel: multiple phrases without intermediate ";;" now really supported;
fixed value printing problems where the wrong printer was selected.

* Debugger: fixed printing problem with local references; revised
handling of checkpoints; various other small fixes.

* Macintosh port: fixed signed division problem in bytecomp/emitcode.ml

Objective Caml 1.04 (11 Mar 1997):
----------------------------------

* Replay debugger ported from Caml Light; added debugger support in
  compiler (option -g) and runtime system. Debugger is alpha-quality
  and needs testing.

* Parsing:
  - Support for "# linenum" directives.
  - At toplevel, allow several phrases without intermediate ";;".

* Typing:
  - Allow constraints on datatype parameters, e.g.
    type 'a foo = ... constraint 'a = 'b * 'c.
  - Fixed bug in signature matching in presence of free type variables '_a.
  - Extensive cleanup of internals of type inference.

* Native-code compilation:
  - Inlining of small functions at point of call (fairly conservative).
  - MIPS code generator ported to SGI IRIX 6.
  - Better code generated for large integer constants.
  - Check for urgent GC when allocating large objects in major heap.
  - PowerPC port: better scheduling, reduced TOC consumption.
  - HPPA port: handle long conditional branches gracefully,
    several span-dependent bugs fixed.

* Standard library:
  - More floating-point functions (all ANSI C float functions now available).
  - Hashtbl: added functorial interface (allow providing own equality
    and hash functions); rehash when resizing, avoid memory leak on
    Hashtbl.remove.
  - Added Char.uppercase, Char.lowercase, String.uppercase, String.lowercase,
    String.capitalize, String.uncapitalize.
  - New module Weak for manipulating weak pointers.
  - New module Callback for registering closures and exceptions to be
    used from C.

* Foreign interface:
  - Better support for callbacks (C calling Caml), exception raising
    from C, and main() in C. Added function to remove a global root.
  - Option -output-obj to package Caml code as a C library.

* Thread library: fixed bug in timed_read and timed_write operations;
  Lexing.from_function and Lexing.from_channel now reentrant.

* Unix interface: renamed EACCESS to EACCES (the POSIX name); added setsid;
  fixed bug in inet_addr_of_string for 64-bit platforms.

* Ocamlyacc: default error function no longer prevents error recovery.

* Ocamllex: fixed reentrancy problem w.r.t. exceptions during refill;
  fixed output problem (\r\r\n) under Win32.

* Macintosh port:
  - The makefiles are provided for compiling and installing O'Caml on
    a Macintosh with MPW 3.4.1.
  - An application with the toplevel in a window is forthcoming.

* Windows NT/95 port: updated toplevel GUI to that of Caml Light 0.73.

* Emacs editing mode and debugger interface included in distribution.


Objective Caml 1.03 (29 Oct 1996):
----------------------------------

* Typing:
  - bug with type names escaping their scope via unification with
    non-generalized type variables '_a completely fixed;
  - fixed bug in occur check : it was too restrictive;
  - fixed bug of coercion operators;
  - check that no two types of the same name are generated in a module
    (there was no check for classes);
  - "#install_printer" works again;
  - fixed bug in printing of subtyping errors;
  - in class interfaces, construct "method m" (without type) change
    the status of method m from abstract to concrete;
  - in a recursive definition of class interfaces, a class can now
    inherit from a previous class;
  - typing of a method make use of an eventual previously given type
    of this method, yielding clearer type errors.

* Compilation (ocamlc and ocamlopt):
  - fixed bug in compilation of classes.

* Native-code compilation:
  - optimization of functions taking tuples of arguments;
  - code emitter for the Motorola 680x0 processors (retrocomputing week);
  - Alpha/OSF1: generate frame descriptors, avoids crashes when e.g.
    exp() or log() cause a domain error; fixed bug with
    String.length "literal";
  - Sparc, Mips, HPPA: removed marking of scanned stack frames
    (benefits do not outweigh cost).

* Standard library:
  - Arg.parse now prints documentation for command-line options;
  - I/O buffers (types in_channel and out_channel) now heap-allocated,
    avoids crashing when closing a channel several times;
  - Overflow bug in compare() fixed;
  - GC bug in raising Sys_error from I/O functions fixed;
  - Parsing.symbol_start works even for epsilon productions.

* Foreign interface: main() in C now working, fixed bug in library
  order at link time.

* Thread library: guard against calling thread functions before Thread.create.

* Unix library: fixed getsockopt, setsockopt, open_process_{in,out}.

* Perl-free, cpp-free, cholesterol-free installation procedure.


Objective Caml 1.02 (27 Sep 1996):
----------------------------------

* Typing:
  - fixed bug with type names escaping their scope via unification
    with non-generalized type variables '_a;
  - keep #class abbreviations longer;
  - faster checking of well-formed abbreviation definitions;
  - stricter checking of "with" constraints over signatures (arity
    mismatch, overriding of an already manifest type).

* Compilation (ocamlc and ocamlopt):
  - fixed bug in compilation of recursive classes;
  - [|...|] and let...rec... allowed inside definitions of recursive
    data structures;

* Bytecode compilation: fixed overflow in linker for programs with
  more than 65535 globals and constants.

* Native-code compilation:
  - ocamlopt ported to HPPA under HP/UX, Intel x86 under Solaris 2,
    PowerMacintosh under MkLinux;
  - fixed two bugs related to floating-point arrays (one with "t array"
    where t is an abstract type implemented as float, one with
    comparison between two float arrays on 32 bit platforms);
  - fixed reloading/spilling problem causing non-termination of
    register allocation;
  - fixed bugs in handling of () causing loss of tail recursion;
  - fixed reloading bug in indirect calls.

* Windows NT/95 port:
  - complete port of the threads library (Pascal Cuoq);
  - partial port of the Unix library (Pascal Cuoq);
  - expansion of *, ? and @ on the command line.

* Standard library:
  - bug in in List.exists2 fixed;
  - bug in "Random.int n" for very large n on 64-bit machines fixed;
  - module Format: added a "general purpose" type of box (open_box);
    can output on several formatters at the same time.

* The "threads" library:
  - implementation on top of native threads available for Win32 and
    POSIX 1003.1c;
  - added -thread option to select a thread-safe version of the
    standard library, the ThreadIO module is no longer needed.

* The "graph" library: avoid invalid pixmaps when doing
  open_graph/close_graph several times.

* The "dynlink" library: support for "private" (no re-export) dynamic loading.

* ocamlyacc: skip '...' character literals correctly.

* C interface: C code linked with O'Caml code can provide its own main()
  and call caml_main() later.


Objective Caml 1.01 (12 Jun 1996):
----------------------------------

* Typing: better report of type incompatibilities;
  non-generalizable type variables in a struct...end no longer flagged
  immediately as an error;
  name clashes during "open" avoided.

* Fixed bug in output_value where identical data structures
  could have different external representations; this bug caused wrong
  "inconsistent assumptions" errors when checking compatibility of
  interfaces at link-time.

* Standard library: fixed bug in Array.blit on overlapping array sections

* Unmarshaling from strings now working.

* ocamlc, ocamlopt: new flags -intf and -impl to force compilation as
  an implementation/an interface, regardless of file extension;
  overflow bug on wide-range integer pattern-matchings fixed.

* ocamlc: fixed bytecode generation bug causing problems with compilation
  units defining more than 256 values

* ocamlopt, all platforms:
  fixed GC bug in "let rec" over data structures;
  link startup file first, fixes "undefined symbol" errors with some
  libraries.

* ocamlopt, Intel x86:
  more efficient calling sequence for calling C functions;
  floating-point wars, chapter 5: don't use float stack for holding
  float pseudo-registers, stack-allocating them is just as efficient.

* ocamlopt, Alpha and Intel x86: more compact calling sequence for garbage
  collection.

* ocamllex: generated automata no longer use callbacks for refilling
  the input buffer (works better with threads); character literals
  correctly skipped inside actions.

* ocamldep: "-I" directories now searched in the right order

* Thread library: incompatibilities with callbacks, signals, and
  dynamic linking removed; scheduling bug with Thread.wait fixed.

* New "dbm" library, interfaces with NDBM.

* Object-oriented extensions:
    instance variables can now be omitted in class types;
    some error messages have been made clearer;
    several bugs fixes.

Objective Caml 1.00 (9 May 1996):
---------------------------------

* Merge of Jérôme Vouillon and Didier Rémy's object-oriented
extensions.

* All libraries: all "new" functions renamed to "create" because "new"
is now a reserved keyword.

* Compilation of "or" patterns (pat1 | pat2) completely revised to
avoid code size explosion.

* Compiler support for preprocessing source files (-pp flag).

* Library construction: flag -linkall to force linking of all units in
a library.

* Native-code compiler: port to the Sparc under NetBSD.

* Toplevel: fixed bug when tracing several times the same function
under different names.

* New format for marshaling arbitrary data structures, allows
marshaling to/from strings.

* Standard library: new module Genlex (configurable lexer for streams)

* Thread library: much better support for I/O and blocking system calls.

* Graphics library: faster reclamation of unused pixmaps.

* Unix library: new functions {set,clear}_nonblock, {set,clear}_close_on_exec,
{set,get}itimer, inet_addr_any, {get,set}sockopt.

* Dynlink library: added support for linking libraries (.cma files).

Caml Special Light 1.15 (15 Mar 1996):
--------------------------------------

* Caml Special Light now runs under Windows NT and 95. Many thanks to
Kevin Gallo (Microsoft Research) who contributed his initial port.

* csllex now generates tables for a table-driven automaton.
The resulting lexers are smaller and run faster.

* Completely automatic configuration script.

* Typing: more stringent checking of module type definitions against
manifest module type specifications.

* Toplevel: recursive definitions of values now working.

* Native-code compiler, all platforms:
        toplevel "let"s with refutable patterns now working;
        fixed bug in assignment to float record fields;
        direct support for floating-point negation and absolute value.

* Native-code compiler, x86: fixed bug with tail calls (with more than
4 arguments) from a function with a one-word stack frame.

* Native-code compiler, Sparc: problem with -compact fixed.

* Thread library: support for non-blocking writes; scheduler revised.

* Unix library: bug in gethostbyaddr fixed; bounds checking for read,
write, etc.

Caml Special Light 1.14 (8 Feb 1996):
-------------------------------------

* cslopt ported to the PowerPC/RS6000 architecture. Better support for
AIX in the bytecode system as well.

* cslopt, all platforms: fixed bug in live range splitting around catch/exit.

* cslopt for the Intel (floating-point wars, chapter 4):
implemented Ershov's algorithm to minimize floating-point stack usage;
out-of-order pops fixed.

* Several bug fixes in callbacks and signals.

Caml Special Light 1.13 (4 Jan 1996):
-------------------------------------

* Pattern-matching compilation revised to factor out accesses inside
matched structures.

* Callbacks and signals now supported in cslopt.
Signals are only detected at allocation points, though.
Added callback functions with 2 and 3 arguments.

* More explicit error messages when a native-code program aborts due
to array or string bound violations.

* In patterns, "C _" allowed even if the constructor C has several arguments.

* && and || allowed as alternate syntax for & and or.

* cslopt for the Intel: code generation for floating-point
operations entirely redone for the third time (a pox on whomever at
Intel decided to organize the floating-point registers as a stack).

* cslopt for the Sparc: don't use Sparc V8 smul and sdiv instructions,
emulation on V7 processors is abysmal.

Caml Special Light 1.12 (30 Nov 1995):
--------------------------------------

* Fixed an embarrassing bug with references to floats.

Caml Special Light 1.11 (29 Nov 1995):
--------------------------------------

* Streams and stream parsers a la Caml Light are back (thanks to
Daniel de Rauglaudre).

* User-level concurrent threads, with low-level shared memory primitives
(locks and conditions) as well as channel-based communication primitives
with first-class synchronous events, in the style of Reppy's CML.

* The native-code compiler has been ported to the HP PA-RISC processor
running under NextStep (sorry, no HPUX, its linker keeps dumping
core on me).

* References not captured in a function are optimized into variables.

* Fixed several bugs related to exceptions.

* Floats behave a little more as specified in the IEEE standard
(believe it or not, but x < y is not the negation of x >= y).

* Lower memory consumption for the native-code compiler.

Caml Special Light 1.10 (07 Nov 1995):
--------------------------------------

* Many bug fixes (too many to list here).

* Module language: introduction of a "with module" notation over
signatures for concise sharing of all type components of a signature;
better support for concrete types in signatures.

* Native-code compiler: the Intel 386 version has been ported to
NextStep and FreeBSD, and generates better code (especially for
floats)

* Tools and libraries: the Caml Light profiler and library for
arbitrary-precision arithmetic have been ported (thanks to John
Malecki and Victor Manuel Gulias Fernandez); better docs for the Unix
and regexp libraries.

Caml Special Light 1.07 (20 Sep 1995):
--------------------------------------

* Syntax: optional ;; allowed in compilation units and structures
(back by popular demand)

* cslopt:
generic handling of float arrays fixed
direct function application when the function expr is not a path fixed
compilation of "let rec" over values fixed
multiple definitions of a value name in a module correctly handled
no calls to ranlib in Solaris

* csltop: #trace now working

* Standard library: added List.memq; documentation of Array fixed.

Caml Special Light 1.06 (12 Sep 1995):
--------------------------------------

* First public release.