Rollup of 9 pull requests

.github/ISSUE_TEMPLATE/library_tracking_issue.md

@@ -2,7 +2,7 @@
 name: Library Tracking Issue
 about: A tracking issue for an unstable library feature.
 title: Tracking Issue for XXX
-labels: C-tracking-issue T-libs
+labels: C-tracking-issue, T-libs
 ---
 <!--
 Thank you for creating a tracking issue!

compiler/rustc_lint/src/lib.rs

@@ -70,7 +70,7 @@ use rustc_middle::ty::TyCtxt;
 use rustc_session::lint::builtin::{
     BARE_TRAIT_OBJECTS, BROKEN_INTRA_DOC_LINKS, ELIDED_LIFETIMES_IN_PATHS,
     EXPLICIT_OUTLIVES_REQUIREMENTS, INVALID_CODEBLOCK_ATTRIBUTES, INVALID_HTML_TAGS,
-    MISSING_DOC_CODE_EXAMPLES, NON_AUTOLINKS, PRIVATE_DOC_TESTS,
+    INVALID_RUST_CODEBLOCK, MISSING_DOC_CODE_EXAMPLES, NON_AUTOLINKS, PRIVATE_DOC_TESTS,
 };
 use rustc_span::symbol::{Ident, Symbol};
 use rustc_span::Span;
@@ -283,7 +283,6 @@ fn register_builtins(store: &mut LintStore, no_interleave_lints: bool) {
         UNUSED_MUT,
         UNREACHABLE_CODE,
         UNREACHABLE_PATTERNS,
-        OVERLAPPING_PATTERNS,
         UNUSED_MUST_USE,
         UNUSED_UNSAFE,
         PATH_STATEMENTS,
@@ -320,6 +319,7 @@ fn register_builtins(store: &mut LintStore, no_interleave_lints: bool) {
         BROKEN_INTRA_DOC_LINKS,
         PRIVATE_INTRA_DOC_LINKS,
         INVALID_CODEBLOCK_ATTRIBUTES,
+        INVALID_RUST_CODEBLOCK,
         MISSING_DOC_CODE_EXAMPLES,
         PRIVATE_DOC_TESTS,
         INVALID_HTML_TAGS
@@ -335,6 +335,7 @@ fn register_builtins(store: &mut LintStore, no_interleave_lints: bool) {
     store.register_renamed("exceeding_bitshifts", "arithmetic_overflow");
     store.register_renamed("redundant_semicolon", "redundant_semicolons");
     store.register_renamed("intra_doc_link_resolution_failure", "broken_intra_doc_links");
+    store.register_renamed("overlapping_patterns", "overlapping_range_endpoints");
     store.register_removed("unknown_features", "replaced by an error");
     store.register_removed("unsigned_negation", "replaced by negate_unsigned feature gate");
     store.register_removed("negate_unsigned", "cast a signed value instead");

compiler/rustc_lint_defs/src/builtin.rs

@@ -588,8 +588,8 @@ declare_lint! {
 }
 
 declare_lint! {
-    /// The `overlapping_patterns` lint detects `match` arms that have
-    /// [range patterns] that overlap.
+    /// The `overlapping_range_endpoints` lint detects `match` arms that have [range patterns] that
+    /// overlap on their endpoints.
     ///
     /// [range patterns]: https://doc.rust-lang.org/nightly/reference/patterns.html#range-patterns
     ///
@@ -607,13 +607,12 @@ declare_lint! {
     ///
     /// ### Explanation
     ///
-    /// It is likely a mistake to have range patterns in a match expression
-    /// that overlap. Check that the beginning and end values are what you
-    /// expect, and keep in mind that with `..=` the left and right bounds are
-    /// inclusive.
-    pub OVERLAPPING_PATTERNS,
+    /// It is likely a mistake to have range patterns in a match expression that overlap in this
+    /// way. Check that the beginning and end values are what you expect, and keep in mind that
+    /// with `..=` the left and right bounds are inclusive.
+    pub OVERLAPPING_RANGE_ENDPOINTS,
     Warn,
-    "detects overlapping patterns"
+    "detects range patterns with overlapping endpoints"
 }
 
 declare_lint! {
@@ -1847,6 +1846,18 @@ declare_lint! {
     "codeblock attribute looks a lot like a known one"
 }
 
+declare_lint! {
+    /// The `invalid_rust_codeblock` lint detects Rust code blocks in
+    /// documentation examples that are invalid (e.g. empty, not parsable as
+    /// Rust code). This is a `rustdoc` only lint, see the documentation in the
+    /// [rustdoc book].
+    ///
+    /// [rustdoc book]: ../../../rustdoc/lints.html#invalid_rust_codeblock
+    pub INVALID_RUST_CODEBLOCK,
+    Warn,
+    "codeblock could not be parsed as valid Rust or is empty"
+}
+
 declare_lint! {
     /// The `missing_crate_level_docs` lint detects if documentation is
     /// missing at the crate root. This is a `rustdoc` only lint, see the
@@ -2809,7 +2820,7 @@ declare_lint_pass! {
         DEAD_CODE,
         UNREACHABLE_CODE,
         UNREACHABLE_PATTERNS,
-        OVERLAPPING_PATTERNS,
+        OVERLAPPING_RANGE_ENDPOINTS,
         BINDINGS_WITH_VARIANT_NAME,
         UNUSED_MACROS,
         WARNINGS,
@@ -2847,6 +2858,7 @@ declare_lint_pass! {
         BROKEN_INTRA_DOC_LINKS,
         PRIVATE_INTRA_DOC_LINKS,
         INVALID_CODEBLOCK_ATTRIBUTES,
+        INVALID_RUST_CODEBLOCK,
         MISSING_CRATE_LEVEL_DOCS,
         MISSING_DOC_CODE_EXAMPLES,
         INVALID_HTML_TAGS,

compiler/rustc_middle/src/lib.rs

@@ -8,7 +8,7 @@
 //! - **MIR.** The "mid-level (M) intermediate representation (IR)" is
 //!   defined in the `mir` module. This module contains only the
 //!   *definition* of the MIR; the passes that transform and operate
-//!   on MIR are found in `librustc_mir` crate.
+//!   on MIR are found in `rustc_mir` crate.
 //! - **Types.** The internal representation of types used in rustc is
 //!   defined in the `ty` module. This includes the **type context**
 //!   (or `tcx`), which is the central context during most of

compiler/rustc_middle/src/lint.rs

@@ -22,8 +22,8 @@ pub enum LintSource {
     Node(Symbol, Span, Option<Symbol> /* RFC 2383 reason */),
 
     /// Lint level was set by a command-line flag.
-    /// The provided `Level` is the level specified on the command line -
-    /// the actual level may be lower due to `--cap-lints`
+    /// The provided `Level` is the level specified on the command line.
+    /// (The actual level may be lower due to `--cap-lints`.)
     CommandLine(Symbol, Level),
 }
 

compiler/rustc_middle/src/ty/query/on_disk_cache.rs

@@ -648,7 +648,7 @@ impl<'sess> OnDiskCache<'sess> {
 
 //- DECODING -------------------------------------------------------------------
 
-/// A decoder that can read from the incr. comp. cache. It is similar to the one
+/// A decoder that can read from the incremental compilation cache. It is similar to the one
 /// we use for crate metadata decoding in that it can rebase spans and eventually
 /// will also handle things that contain `Ty` instances.
 crate struct CacheDecoder<'a, 'tcx> {
@@ -936,7 +936,7 @@ impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for &'tcx [Span] {
 
 //- ENCODING -------------------------------------------------------------------
 
-/// An encoder that can write the incr. comp. cache.
+/// An encoder that can write to the incremental compilation cache.
 struct CacheEncoder<'a, 'tcx, E: OpaqueEncoder> {
     tcx: TyCtxt<'tcx>,
     encoder: &'a mut E,

compiler/rustc_mir/src/transform/coverage/mod.rs

@@ -30,6 +30,7 @@ use rustc_middle::mir::{
 };
 use rustc_middle::ty::TyCtxt;
 use rustc_span::def_id::DefId;
+use rustc_span::source_map::SourceMap;
 use rustc_span::{CharPos, Pos, SourceFile, Span, Symbol};
 
 /// A simple error message wrapper for `coverage::Error`s.
@@ -311,7 +312,7 @@ impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
                 self.mir_body,
                 counter_kind,
                 self.bcb_leader_bb(bcb),
-                Some(make_code_region(file_name, &self.source_file, span, body_span)),
+                Some(make_code_region(source_map, file_name, &self.source_file, span, body_span)),
             );
         }
     }
@@ -489,6 +490,7 @@ fn inject_intermediate_expression(mir_body: &mut mir::Body<'tcx>, expression: Co
 
 /// Convert the Span into its file name, start line and column, and end line and column
 fn make_code_region(
+    source_map: &SourceMap,
     file_name: Symbol,
     source_file: &Lrc<SourceFile>,
     span: Span,
@@ -508,6 +510,8 @@ fn make_code_region(
     } else {
         source_file.lookup_file_pos(span.hi())
     };
+    let start_line = source_map.doctest_offset_line(&source_file.name, start_line);
+    let end_line = source_map.doctest_offset_line(&source_file.name, end_line);
     CodeRegion {
         file_name,
         start_line: start_line as u32,

compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs

@@ -161,7 +161,7 @@ impl IntRange {
         // 2       --------   // 2 -------
         let (lo, hi) = self.boundaries();
         let (other_lo, other_hi) = other.boundaries();
-        lo == other_hi || hi == other_lo
+        (lo == other_hi || hi == other_lo) && !self.is_singleton() && !other.is_singleton()
     }
 
     fn to_pat<'tcx>(&self, tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Pat<'tcx> {
@@ -273,7 +273,7 @@ impl IntRange {
         let mut borders: Vec<_> = row_borders.chain(self_borders).collect();
         borders.sort_unstable();
 
-        self.lint_overlapping_patterns(pcx, hir_id, overlaps);
+        self.lint_overlapping_range_endpoints(pcx, hir_id, overlaps);
 
         // We're going to iterate through every adjacent pair of borders, making sure that
         // each represents an interval of nonnegative length, and convert each such
@@ -296,30 +296,30 @@ impl IntRange {
             .collect()
     }
 
-    fn lint_overlapping_patterns(
+    fn lint_overlapping_range_endpoints(
         &self,
         pcx: PatCtxt<'_, '_, '_>,
         hir_id: Option<HirId>,
         overlaps: Vec<(IntRange, Span)>,
     ) {
         if let (true, Some(hir_id)) = (!overlaps.is_empty(), hir_id) {
             pcx.cx.tcx.struct_span_lint_hir(
-                lint::builtin::OVERLAPPING_PATTERNS,
+                lint::builtin::OVERLAPPING_RANGE_ENDPOINTS,
                 hir_id,
                 pcx.span,
                 |lint| {
-                    let mut err = lint.build("multiple patterns covering the same range");
-                    err.span_label(pcx.span, "overlapping patterns");
+                    let mut err = lint.build("multiple patterns overlap on their endpoints");
                     for (int_range, span) in overlaps {
-                        // Use the real type for user display of the ranges:
                         err.span_label(
                             span,
                             &format!(
-                                "this range overlaps on `{}`",
-                                int_range.to_pat(pcx.cx.tcx, pcx.ty),
+                                "this range overlaps on `{}`...",
+                                int_range.to_pat(pcx.cx.tcx, pcx.ty)
                             ),
                         );
                     }
+                    err.span_label(pcx.span, "... with this range");
+                    err.note("you likely meant to write mutually exclusive ranges");
                     err.emit();
                 },
             );

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -1912,4 +1912,22 @@ impl<'a> Parser<'a> {
         *self = snapshot;
         Err(err)
     }
+
+    /// Get the diagnostics for the cases where `move async` is found.
+    ///
+    /// `move_async_span` starts at the 'm' of the move keyword and ends with the 'c' of the async keyword
+    pub(super) fn incorrect_move_async_order_found(
+        &self,
+        move_async_span: Span,
+    ) -> DiagnosticBuilder<'a> {
+        let mut err =
+            self.struct_span_err(move_async_span, "the order of `move` and `async` is incorrect");
+        err.span_suggestion_verbose(
+            move_async_span,
+            "try switching the order",
+            "async move".to_owned(),
+            Applicability::MaybeIncorrect,
+        );
+        err
+    }
 }

compiler/rustc_parse/src/parser/expr.rs

@@ -1603,7 +1603,7 @@ impl<'a> Parser<'a> {
             self.sess.gated_spans.gate(sym::async_closure, span);
         }
 
-        let capture_clause = self.parse_capture_clause();
+        let capture_clause = self.parse_capture_clause()?;
         let decl = self.parse_fn_block_decl()?;
         let decl_hi = self.prev_token.span;
         let body = match decl.output {
@@ -1626,8 +1626,18 @@ impl<'a> Parser<'a> {
     }
 
     /// Parses an optional `move` prefix to a closure-like construct.
-    fn parse_capture_clause(&mut self) -> CaptureBy {
-        if self.eat_keyword(kw::Move) { CaptureBy::Value } else { CaptureBy::Ref }
+    fn parse_capture_clause(&mut self) -> PResult<'a, CaptureBy> {
+        if self.eat_keyword(kw::Move) {
+            // Check for `move async` and recover
+            if self.check_keyword(kw::Async) {
+                let move_async_span = self.token.span.with_lo(self.prev_token.span.data().lo);
+                Err(self.incorrect_move_async_order_found(move_async_span))
+            } else {
+                Ok(CaptureBy::Value)
+            }
+        } else {
+            Ok(CaptureBy::Ref)
+        }
     }
 
     /// Parses the `|arg, arg|` header of a closure.
@@ -2019,7 +2029,7 @@ impl<'a> Parser<'a> {
     fn parse_async_block(&mut self, mut attrs: AttrVec) -> PResult<'a, P<Expr>> {
         let lo = self.token.span;
         self.expect_keyword(kw::Async)?;
-        let capture_clause = self.parse_capture_clause();
+        let capture_clause = self.parse_capture_clause()?;
         let (iattrs, body) = self.parse_inner_attrs_and_block()?;
         attrs.extend(iattrs);
         let kind = ExprKind::Async(capture_clause, DUMMY_NODE_ID, body);

compiler/rustc_span/src/lib.rs

@@ -182,7 +182,7 @@ impl std::fmt::Display for FileName {
         use FileName::*;
         match *self {
             Real(RealFileName::Named(ref path)) => write!(fmt, "{}", path.display()),
-            // FIXME: might be nice to display both compoments of Devirtualized.
+            // FIXME: might be nice to display both components of Devirtualized.
             // But for now (to backport fix for issue #70924), best to not
             // perturb diagnostics so its obvious test suite still works.
             Real(RealFileName::Devirtualized { ref local_path, virtual_name: _ }) => {

compiler/rustc_trait_selection/src/opaque_types.rs

@@ -46,6 +46,7 @@ pub struct OpaqueTypeDecl<'tcx> {
     /// type Foo = impl Baz;
     /// fn bar() -> Foo {
     /// //          ^^^ This is the span we are looking for!
+    /// # }
     /// ```
     ///
     /// In cases where the fn returns `(impl Trait, impl Trait)` or

library/core/src/array/mod.rs

@@ -463,6 +463,37 @@ impl<T, const N: usize> [T; N] {
         unsafe { crate::mem::transmute_copy::<_, [U; N]>(&dst) }
     }
 
+    /// 'Zips up' two arrays into a single array of pairs.
+    ///
+    /// `zip()` returns a new array where every element is a tuple where the
+    /// first element comes from the first array, and the second element comes
+    /// from the second array. In other words, it zips two arrays together,
+    /// into a single one.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(array_zip)]
+    /// let x = [1, 2, 3];
+    /// let y = [4, 5, 6];
+    /// let z = x.zip(y);
+    /// assert_eq!(z, [(1, 4), (2, 5), (3, 6)]);
+    /// ```
+    #[unstable(feature = "array_zip", issue = "80094")]
+    pub fn zip<U>(self, rhs: [U; N]) -> [(T, U); N] {
+        use crate::mem::MaybeUninit;
+
+        let mut dst = MaybeUninit::uninit_array::<N>();
+        for (i, (lhs, rhs)) in IntoIter::new(self).zip(IntoIter::new(rhs)).enumerate() {
+            dst[i].write((lhs, rhs));
+        }
+        // FIXME: Convert to crate::mem::transmute once it works with generics.
+        // unsafe { crate::mem::transmute::<[MaybeUninit<U>; N], [U; N]>(dst) }
+        // SAFETY: At this point we've properly initialized the whole array
+        // and we just need to cast it to the correct type.
+        unsafe { crate::mem::transmute_copy::<_, [(T, U); N]>(&dst) }
+    }
+
     /// Returns a slice containing the entire array. Equivalent to `&s[..]`.
     #[unstable(feature = "array_methods", issue = "76118")]
     pub fn as_slice(&self) -> &[T] {

src/doc/rustdoc/src/lints.md

@@ -285,6 +285,41 @@ warning: unclosed HTML tag `h1`
 
 warning: 2 warnings emitted
 ```
+
+## invalid_rust_codeblock
+
+This lint **warns by default**. It detects Rust code blocks in documentation
+examples that are invalid (e.g. empty, not parsable as Rust). For example:
+
+```rust
+/// Empty code block, with and without Rust:
+///
+/// ```rust
+/// ```
+///
+/// Unclosed code block:
+///
+/// ```rust
+fn main() {}
+```
+
+Which will give:
+
+```text
+warning: Rust code block is empty
+ --> src/lib.rs:3:5
+  |
+3 |   /// ```rust
+  |  _____^
+4 | | /// ```
+  | |_______^
+
+warning: Rust code block is empty
+ --> src/lib.rs:8:5
+  |
+8 | /// ```rust
+  |     ^^^^^^^
+```
 
 ## non_autolinks