Auto merge of #40148 - frewsxcv:rollup, r=frewsxcv

Rollup of 9 pull requests

- Successful merges: #39977, #40033, #40047, #40056, #40057, #40122, #40124, #40126, #40131
- Failed merges: #40101

Author: bors

CONTRIBUTING.md

@@ -97,33 +97,38 @@ system internals, try asking in [`#rust-internals`][pound-rust-internals].
 
 Before you can start building the compiler you need to configure the build for
 your system. In most cases, that will just mean using the defaults provided
-for Rust. Configuring involves invoking the `configure` script in the project
-root.
+for Rust.
 
-```
-./configure
-```
+To change configuration, you must copy the file `src/bootstrap/config.toml.example`
+to `config.toml` in the directory from which you will be running the build, and
+change the settings provided.
+
+There are large number of options provided in this config file that will alter the
+configuration used in the build process. Some options to note:
 
-There are large number of options accepted by this script to alter the
-configuration used later in the build process. Some options to note:
+#### `[llvm]`:
+- `ccache = true` - Use ccache when building llvm
 
-- `--enable-debug` - Build a debug version of the compiler (disables optimizations,
-    which speeds up compilation of stage1 rustc)
-- `--enable-optimize` - Enable optimizations (can be used with `--enable-debug`
-    to make a debug build with optimizations)
-- `--disable-valgrind-rpass` - Don't run tests with valgrind
-- `--enable-clang` - Prefer clang to gcc for building dependencies (e.g., LLVM)
-- `--enable-ccache` - Invoke clang/gcc with ccache to re-use object files between builds
-- `--enable-compiler-docs` - Build compiler documentation
+#### `[build]`:
+- `compiler-docs = true` - Build compiler documentation
 
-To see a full list of options, run `./configure --help`.
+#### `[rust]`:
+- `debuginfo = true` - Build a compiler with debuginfo
+- `optimize = false` - Disable optimizations to speed up compilation of stage1 rust
+
+For more options, the `config.toml` file contains commented out defaults, with
+descriptions of what each option will do.
+
+Note: Previously the `./configure` script was used to configure this
+project. It can still be used, but it's recommended to use a `config.toml`
+file. If you still have a `config.mk` file in your directory - from
+`./configure` - you may need to delete it for `config.toml` to work.
 
 ### Building
 
-Although the `./configure` script will generate a `Makefile`, this is actually
-just a thin veneer over the actual build system driver, `x.py`. This file, at
-the root of the repository, is used to build, test, and document various parts
-of the compiler. You can execute it as:
+The build system uses the `x.py` script to control the build process. This script
+is used to build, test, and document various parts of the compiler. You can
+execute it as:
 
 ```sh
 python x.py build
@@ -185,6 +190,9 @@ To learn about all possible rules you can execute, run:
 python x.py build --help --verbose
 ```
 
+Note: Previously `./configure` and `make` were used to build this project.
+They are still available, but `x.py` is the recommended build system.
+
 ### Useful commands
 
 Some common invocations of `x.py` are:
@@ -235,8 +243,8 @@ feature. We use the 'fork and pull' model described there.
 
 Please make pull requests against the `master` branch.
 
-Compiling all of `make check` can take a while. When testing your pull request,
-consider using one of the more specialized `make` targets to cut down on the
+Compiling all of `./x.py test` can take a while. When testing your pull request,
+consider using one of the more specialized `./x.py` targets to cut down on the
 amount of time you have to wait. You need to have built the compiler at least
 once before running these will work, but that’s only one full build rather than
 one each time.
@@ -307,7 +315,7 @@ To find documentation-related issues, sort by the [A-docs label][adocs].
 
 [adocs]: https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AA-docs
 
-In many cases, you don't need a full `make doc`. You can use `rustdoc` directly
+In many cases, you don't need a full `./x.py doc`. You can use `rustdoc` directly
 to check small fixes. For example, `rustdoc src/doc/reference.md` will render
 reference to `doc/reference.html`. The CSS might be messed up, but you can
 verify that the HTML is right.

README.md

@@ -35,15 +35,15 @@ Read ["Installing Rust"] from [The Book].
 3. Build and install:
 
     ```sh
-    $ ./configure
-    $ make && sudo make install
+    $ ./x.py build && sudo ./x.py dist --install
     ```
 
-    > ***Note:*** Install locations can be adjusted by passing a `--prefix`
-    > argument to `configure`. Various other options are also supported – pass
-    > `--help` for more information on them.
+    > ***Note:*** Install locations can be adjusted by copying the config file
+    > from `./src/bootstrap/config.toml.example` to `./config.toml`, and
+    > adjusting the `prefix` option under `[install]`. Various other options are
+    > also supported, and are documented in the config file.
 
-    When complete, `sudo make install` will place several programs into
+    When complete, `sudo ./x.py dist --install` will place several programs into
     `/usr/local/bin`: `rustc`, the Rust compiler, and `rustdoc`, the
     API-documentation tool. This install does not include [Cargo],
     Rust's package manager, which you may also want to build.
@@ -59,7 +59,6 @@ for interop with software produced by Visual Studio use the MSVC build of Rust;
 for interop with GNU software built using the MinGW/MSYS2 toolchain use the GNU
 build.
 
-
 #### MinGW
 
 [MSYS2][msys2] can be used to easily build Rust on Windows:
@@ -94,11 +93,10 @@ build.
                mingw-w64-x86_64-gcc
    ```
 
-4. Navigate to Rust's source code (or clone it), then configure and build it:
+4. Navigate to Rust's source code (or clone it), then build it:
 
    ```sh
-   $ ./configure
-   $ make && make install
+   $ ./x.py build && ./x.py dist --install
    ```
 
 #### MSVC
@@ -114,13 +112,6 @@ shell with:
 > python x.py build
 ```
 
-If you're running inside of an msys shell, however, you can run:
-
-```sh
-$ ./configure --build=x86_64-pc-windows-msvc
-$ make && make install
-```
-
 Currently building Rust only works with some known versions of Visual Studio. If
 you have a more recent version installed the build system doesn't understand
 then you may need to force rustbuild to use an older version. This can be done
@@ -131,13 +122,43 @@ CALL "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\bin\amd64\vcvars64.
 python x.py build
 ```
 
+#### Specifying an ABI
+
+Each specific ABI can also be used from either environment (for example, using
+the GNU ABI in powershell) by using an explicit build triple. The available
+Windows build triples are:
+- GNU ABI (using GCC)
+    - `i686-pc-windows-gnu`
+    - `x86_64-pc-windows-gnu`
+- The MSVC ABI
+    - `i686-pc-windows-msvc`
+    - `x86_64-pc-windows-msvc`
+
+The build triple can be specified by either specifying `--build=ABI` when
+invoking `x.py` commands, or by copying the `config.toml` file (as described
+in Building From Source), and modifying the `build` option under the `[build]`
+section.
+
+### Configure and Make
+
+While it's not the recommended build system, this project also provides a
+configure script and makefile (the latter of which just invokes `x.py`).
+
+```sh
+$ ./configure
+$ make && sudo make install
+```
+
+When using the configure script, the generated config.mk` file may override the
+`config.toml` file. To go back to the `config.toml` file, delete the generated
+`config.mk` file.
+
 ## Building Documentation
 
 If you’d like to build the documentation, it’s almost the same:
 
 ```sh
-$ ./configure
-$ make docs
+$ ./x.py doc
 ```
 
 The generated documentation will appear in a top-level `doc` directory,

src/doc/book/src/lifetimes.md

@@ -349,8 +349,8 @@ to it.
 
 ## Lifetime Elision
 
-Rust supports powerful local type inference in the bodies of functions but not in their item signatures. 
-It's forbidden to allow reasoning about types based on the item signature alone. 
+Rust supports powerful local type inference in the bodies of functions, but it
+deliberately does not perform any reasoning about types for item signatures. 
 However, for ergonomic reasons, a very restricted secondary inference algorithm called 
 “lifetime elision” does apply when judging lifetimes. Lifetime elision is concerned solely with inferring 
 lifetime parameters using three easily memorizable and unambiguous rules. This means lifetime elision 

src/doc/book/src/procedural-macros.md

@@ -128,7 +128,7 @@ pub fn hello_world(input: TokenStream) -> TokenStream {
 So there is a lot going on here. We have introduced two new crates: [`syn`] and
 [`quote`]. As you may have noticed, `input: TokenSteam` is immediately converted
 to a `String`. This `String` is a string representation of the Rust code for which
-we are deriving `HelloWorld` for. At the moment, the only thing you can do with a
+we are deriving `HelloWorld`. At the moment, the only thing you can do with a
 `TokenStream` is convert it to a string. A richer API will exist in the future.
 
 So what we really need is to be able to _parse_ Rust code into something

src/libcore/fmt/mod.rs

@@ -65,12 +65,15 @@ pub struct Error;
 /// A collection of methods that are required to format a message into a stream.
 ///
 /// This trait is the type which this modules requires when formatting
-/// information. This is similar to the standard library's `io::Write` trait,
+/// information. This is similar to the standard library's [`io::Write`] trait,
 /// but it is only intended for use in libcore.
 ///
 /// This trait should generally not be implemented by consumers of the standard
-/// library. The `write!` macro accepts an instance of `io::Write`, and the
-/// `io::Write` trait is favored over implementing this trait.
+/// library. The [`write!`] macro accepts an instance of [`io::Write`], and the
+/// [`io::Write`] trait is favored over implementing this trait.
+///
+/// [`write!`]: ../../std/macro.write.html
+/// [`io::Write`]: ../../std/io/trait.Write.html
 #[stable(feature = "rust1", since = "1.0.0")]
 pub trait Write {
     /// Writes a slice of bytes into this writer, returning whether the write
@@ -82,29 +85,79 @@ pub trait Write {
     ///
     /// # Errors
     ///
-    /// This function will return an instance of `Error` on error.
+    /// This function will return an instance of [`Error`] on error.
+    ///
+    /// [`Error`]: struct.Error.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::fmt::{Error, Write};
+    ///
+    /// fn writer<W: Write>(f: &mut W, s: &str) -> Result<(), Error> {
+    ///     f.write_str(s)
+    /// }
+    ///
+    /// let mut buf = String::new();
+    /// writer(&mut buf, "hola").unwrap();
+    /// assert_eq!(&buf, "hola");
+    /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     fn write_str(&mut self, s: &str) -> Result;
 
-    /// Writes a `char` into this writer, returning whether the write succeeded.
+    /// Writes a [`char`] into this writer, returning whether the write succeeded.
     ///
-    /// A single `char` may be encoded as more than one byte.
+    /// A single [`char`] may be encoded as more than one byte.
     /// This method can only succeed if the entire byte sequence was successfully
     /// written, and this method will not return until all data has been
     /// written or an error occurs.
     ///
     /// # Errors
     ///
-    /// This function will return an instance of `Error` on error.
+    /// This function will return an instance of [`Error`] on error.
+    ///
+    /// [`char`]: ../../std/primitive.char.html
+    /// [`Error`]: struct.Error.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::fmt::{Error, Write};
+    ///
+    /// fn writer<W: Write>(f: &mut W, c: char) -> Result<(), Error> {
+    ///     f.write_char(c)
+    /// }
+    ///
+    /// let mut buf = String::new();
+    /// writer(&mut buf, 'a').unwrap();
+    /// writer(&mut buf, 'b').unwrap();
+    /// assert_eq!(&buf, "ab");
+    /// ```
     #[stable(feature = "fmt_write_char", since = "1.1.0")]
     fn write_char(&mut self, c: char) -> Result {
         self.write_str(c.encode_utf8(&mut [0; 4]))
     }
 
-    /// Glue for usage of the `write!` macro with implementors of this trait.
+    /// Glue for usage of the [`write!`] macro with implementors of this trait.
     ///
     /// This method should generally not be invoked manually, but rather through
-    /// the `write!` macro itself.
+    /// the [`write!`] macro itself.
+    ///
+    /// [`write!`]: ../../std/macro.write.html
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::fmt::{Error, Write};
+    ///
+    /// fn writer<W: Write>(f: &mut W, s: &str) -> Result<(), Error> {
+    ///     f.write_fmt(format_args!("{}", s))
+    /// }
+    ///
+    /// let mut buf = String::new();
+    /// writer(&mut buf, "world").unwrap();
+    /// assert_eq!(&buf, "world");
+    /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     fn write_fmt(&mut self, args: Arguments) -> Result {
         // This Adapter is needed to allow `self` (of type `&mut