Rollup of 9 pull requests

compiler/rustc_expand/src/base.rs

@@ -796,9 +796,15 @@ impl SyntaxExtension {
     /// | external      | no  | if-ext        | if-ext   | yes |
     /// | yes           | yes | yes           | yes      | yes |
     fn get_collapse_debuginfo(sess: &Session, attrs: &[ast::Attribute], is_local: bool) -> bool {
-        let collapse_debuginfo_attr = attr::find_by_name(attrs, sym::collapse_debuginfo)
+        let mut collapse_debuginfo_attr = attr::find_by_name(attrs, sym::collapse_debuginfo)
             .map(|v| Self::collapse_debuginfo_by_name(sess, v))
             .unwrap_or(CollapseMacroDebuginfo::Unspecified);
+        if collapse_debuginfo_attr == CollapseMacroDebuginfo::Unspecified
+            && attr::contains_name(attrs, sym::rustc_builtin_macro)
+        {
+            collapse_debuginfo_attr = CollapseMacroDebuginfo::Yes;
+        }
+
         let flag = sess.opts.unstable_opts.collapse_macro_debuginfo;
         let attr = collapse_debuginfo_attr;
         let ext = !is_local;

compiler/rustc_feature/src/unstable.rs

@@ -516,6 +516,9 @@ declare_features! (
     (unstable, macro_metavar_expr, "1.61.0", Some(83527)),
     /// Allows `#[marker]` on certain traits allowing overlapping implementations.
     (unstable, marker_trait_attr, "1.30.0", Some(29864)),
+    /// Allows exhaustive pattern matching on types that contain uninhabited types in cases that are
+    /// unambiguously sound.
+    (incomplete, min_exhaustive_patterns, "CURRENT_RUSTC_VERSION", Some(119612)),
     /// A minimal, sound subset of specialization intended to be used by the
     /// standard library until the soundness issues with specialization
     /// are fixed.

compiler/rustc_pattern_analysis/src/lib.rs

@@ -95,6 +95,7 @@ pub trait TypeCx: Sized + fmt::Debug {
     type PatData: Clone;
 
     fn is_exhaustive_patterns_feature_on(&self) -> bool;
+    fn is_min_exhaustive_patterns_feature_on(&self) -> bool;
 
     /// The number of fields for this constructor.
     fn ctor_arity(&self, ctor: &Constructor<Self>, ty: &Self::Ty) -> usize;

compiler/rustc_pattern_analysis/src/rustc.rs

@@ -181,7 +181,9 @@ impl<'p, 'tcx> RustcMatchCheckCtxt<'p, 'tcx> {
             // `field.ty()` doesn't normalize after substituting.
             let ty = cx.tcx.normalize_erasing_regions(cx.param_env, ty);
             let is_visible = adt.is_enum() || field.vis.is_accessible_from(cx.module, cx.tcx);
-            let is_uninhabited = cx.tcx.features().exhaustive_patterns && cx.is_uninhabited(ty);
+            let is_uninhabited = (cx.tcx.features().exhaustive_patterns
+                || cx.tcx.features().min_exhaustive_patterns)
+                && cx.is_uninhabited(ty);
 
             if is_uninhabited && (!is_visible || is_non_exhaustive) {
                 None
@@ -863,6 +865,9 @@ impl<'p, 'tcx> TypeCx for RustcMatchCheckCtxt<'p, 'tcx> {
     fn is_exhaustive_patterns_feature_on(&self) -> bool {
         self.tcx.features().exhaustive_patterns
     }
+    fn is_min_exhaustive_patterns_feature_on(&self) -> bool {
+        self.tcx.features().min_exhaustive_patterns
+    }
 
     fn ctor_arity(&self, ctor: &crate::constructor::Constructor<Self>, ty: &Self::Ty) -> usize {
         self.ctor_arity(ctor, *ty)

compiler/rustc_pattern_analysis/src/usefulness.rs

@@ -548,11 +548,12 @@
 //! [`ValidityConstraint::specialize`].
 //!
 //! Having said all that, in practice we don't fully follow what's been presented in this section.
-//! Under `exhaustive_patterns`, we allow omitting empty arms even in `!known_valid` places, for
-//! backwards-compatibility until we have a better alternative. Without `exhaustive_patterns`, we
-//! mostly treat empty types as inhabited, except specifically a non-nested `!` or empty enum. In
-//! this specific case we also allow the empty match regardless of place validity, for
-//! backwards-compatibility. Hopefully we can eventually deprecate this.
+//! Let's call "toplevel exception" the case where the match scrutinee itself has type `!` or
+//! `EmptyEnum`. First, on stable rust, we require `_` patterns for empty types in all cases apart
+//! from the toplevel exception. The `exhaustive_patterns` and `min_exaustive_patterns` allow
+//! omitting patterns in the cases described above. There's a final detail: in the toplevel
+//! exception or with the `exhaustive_patterns` feature, we ignore place validity when checking
+//! whether a pattern is required for exhaustiveness. I (Nadrieril) hope to deprecate this behavior.
 //!
 //!
 //!
@@ -1442,10 +1443,17 @@ fn compute_exhaustiveness_and_usefulness<'a, 'p, Cx: TypeCx>(
     // We treat match scrutinees of type `!` or `EmptyEnum` differently.
     let is_toplevel_exception =
         is_top_level && matches!(ctors_for_ty, ConstructorSet::NoConstructors);
-    // Whether empty patterns can be omitted for exhaustiveness.
-    let can_omit_empty_arms = is_toplevel_exception || mcx.tycx.is_exhaustive_patterns_feature_on();
-    // Whether empty patterns are counted as useful or not.
-    let empty_arms_are_unreachable = place_validity.is_known_valid() && can_omit_empty_arms;
+    // Whether empty patterns are counted as useful or not. We only warn an empty arm unreachable if
+    // it is guaranteed unreachable by the opsem (i.e. if the place is `known_valid`).
+    let empty_arms_are_unreachable = place_validity.is_known_valid()
+        && (is_toplevel_exception
+            || mcx.tycx.is_exhaustive_patterns_feature_on()
+            || mcx.tycx.is_min_exhaustive_patterns_feature_on());
+    // Whether empty patterns can be omitted for exhaustiveness. We ignore place validity in the
+    // toplevel exception and `exhaustive_patterns` cases for backwards compatibility.
+    let can_omit_empty_arms = empty_arms_are_unreachable
+        || is_toplevel_exception
+        || mcx.tycx.is_exhaustive_patterns_feature_on();
 
     // Analyze the constructors present in this column.
     let ctors = matrix.heads().map(|p| p.ctor());

compiler/rustc_resolve/src/late.rs

@@ -4424,35 +4424,6 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
             ExprKind::Type(ref _type_expr, ref _ty) => {
                 visit::walk_expr(self, expr);
             }
-            // `async |x| ...` gets desugared to `|x| async {...}`, so we need to
-            // resolve the arguments within the proper scopes so that usages of them inside the
-            // closure are detected as upvars rather than normal closure arg usages.
-            //
-            // Similarly, `gen |x| ...` gets desugared to `|x| gen {...}`, so we handle that too.
-            ExprKind::Closure(box ast::Closure {
-                coroutine_kind: Some(_),
-                ref fn_decl,
-                ref body,
-                ..
-            }) => {
-                self.with_rib(ValueNS, RibKind::Normal, |this| {
-                    this.with_label_rib(RibKind::FnOrCoroutine, |this| {
-                        // Resolve arguments:
-                        this.resolve_params(&fn_decl.inputs);
-                        // No need to resolve return type --
-                        // the outer closure return type is `FnRetTy::Default`.
-
-                        // Now resolve the inner closure
-                        {
-                            // No need to resolve arguments: the inner closure has none.
-                            // Resolve the return type:
-                            visit::walk_fn_ret_ty(this, &fn_decl.output);
-                            // Resolve the body
-                            this.visit_expr(body);
-                        }
-                    })
-                });
-            }
             // For closures, RibKind::FnOrCoroutine is added in visit_fn
             ExprKind::Closure(box ast::Closure {
                 binder: ClosureBinder::For { ref generic_params, span },

compiler/rustc_span/src/symbol.rs

@@ -1029,6 +1029,7 @@ symbols! {
         min_const_fn,
         min_const_generics,
         min_const_unsafe_fn,
+        min_exhaustive_patterns,
         min_specialization,
         min_type_alias_impl_trait,
         minnumf32,

library/alloc/src/lib.rs

@@ -149,7 +149,6 @@
 #![feature(set_ptr_value)]
 #![feature(sized_type_properties)]
 #![feature(slice_from_ptr_range)]
-#![feature(slice_group_by)]
 #![feature(slice_ptr_get)]
 #![feature(slice_ptr_len)]
 #![feature(slice_range)]

library/alloc/src/slice.rs

@@ -51,14 +51,14 @@ pub use core::slice::{from_mut, from_ref};
 pub use core::slice::{from_mut_ptr_range, from_ptr_range};
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::slice::{from_raw_parts, from_raw_parts_mut};
+#[stable(feature = "slice_group_by", since = "CURRENT_RUSTC_VERSION")]
+pub use core::slice::{ChunkBy, ChunkByMut};
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::slice::{Chunks, Windows};
 #[stable(feature = "chunks_exact", since = "1.31.0")]
 pub use core::slice::{ChunksExact, ChunksExactMut};
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::slice::{ChunksMut, Split, SplitMut};
-#[unstable(feature = "slice_group_by", issue = "80552")]
-pub use core::slice::{GroupBy, GroupByMut};
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::slice::{Iter, IterMut};
 #[stable(feature = "rchunks", since = "1.31.0")]

library/alloc/src/str.rs

@@ -30,6 +30,8 @@ pub use core::str::SplitAsciiWhitespace;
 pub use core::str::SplitInclusive;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::str::SplitWhitespace;
+#[unstable(feature = "str_from_raw_parts", issue = "119206")]
+pub use core::str::{from_raw_parts, from_raw_parts_mut};
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::str::{from_utf8, from_utf8_mut, Bytes, CharIndices, Chars};
 #[stable(feature = "rust1", since = "1.0.0")]

library/alloc/tests/lib.rs

@@ -29,7 +29,6 @@
 #![feature(iter_advance_by)]
 #![feature(iter_next_chunk)]
 #![feature(round_char_boundary)]
-#![feature(slice_group_by)]
 #![feature(slice_partition_dedup)]
 #![feature(string_remove_matches)]
 #![feature(const_btree_len)]

library/alloc/tests/slice.rs

@@ -1614,26 +1614,26 @@ fn subslice_patterns() {
 }
 
 #[test]
-fn test_group_by() {
+fn test_chunk_by() {
     let slice = &[1, 1, 1, 3, 3, 2, 2, 2, 1, 0];
 
-    let mut iter = slice.group_by(|a, b| a == b);
+    let mut iter = slice.chunk_by(|a, b| a == b);
     assert_eq!(iter.next(), Some(&[1, 1, 1][..]));
     assert_eq!(iter.next(), Some(&[3, 3][..]));
     assert_eq!(iter.next(), Some(&[2, 2, 2][..]));
     assert_eq!(iter.next(), Some(&[1][..]));
     assert_eq!(iter.next(), Some(&[0][..]));
     assert_eq!(iter.next(), None);
 
-    let mut iter = slice.group_by(|a, b| a == b);
+    let mut iter = slice.chunk_by(|a, b| a == b);
     assert_eq!(iter.next_back(), Some(&[0][..]));
     assert_eq!(iter.next_back(), Some(&[1][..]));
     assert_eq!(iter.next_back(), Some(&[2, 2, 2][..]));
     assert_eq!(iter.next_back(), Some(&[3, 3][..]));
     assert_eq!(iter.next_back(), Some(&[1, 1, 1][..]));
     assert_eq!(iter.next_back(), None);
 
-    let mut iter = slice.group_by(|a, b| a == b);
+    let mut iter = slice.chunk_by(|a, b| a == b);
     assert_eq!(iter.next(), Some(&[1, 1, 1][..]));
     assert_eq!(iter.next_back(), Some(&[0][..]));
     assert_eq!(iter.next(), Some(&[3, 3][..]));
@@ -1643,26 +1643,26 @@ fn test_group_by() {
 }
 
 #[test]
-fn test_group_by_mut() {
+fn test_chunk_by_mut() {
     let slice = &mut [1, 1, 1, 3, 3, 2, 2, 2, 1, 0];
 
-    let mut iter = slice.group_by_mut(|a, b| a == b);
+    let mut iter = slice.chunk_by_mut(|a, b| a == b);
     assert_eq!(iter.next(), Some(&mut [1, 1, 1][..]));
     assert_eq!(iter.next(), Some(&mut [3, 3][..]));
     assert_eq!(iter.next(), Some(&mut [2, 2, 2][..]));
     assert_eq!(iter.next(), Some(&mut [1][..]));
     assert_eq!(iter.next(), Some(&mut [0][..]));
     assert_eq!(iter.next(), None);
 
-    let mut iter = slice.group_by_mut(|a, b| a == b);
+    let mut iter = slice.chunk_by_mut(|a, b| a == b);
     assert_eq!(iter.next_back(), Some(&mut [0][..]));
     assert_eq!(iter.next_back(), Some(&mut [1][..]));
     assert_eq!(iter.next_back(), Some(&mut [2, 2, 2][..]));
     assert_eq!(iter.next_back(), Some(&mut [3, 3][..]));
     assert_eq!(iter.next_back(), Some(&mut [1, 1, 1][..]));
     assert_eq!(iter.next_back(), None);
 
-    let mut iter = slice.group_by_mut(|a, b| a == b);
+    let mut iter = slice.chunk_by_mut(|a, b| a == b);
     assert_eq!(iter.next(), Some(&mut [1, 1, 1][..]));
     assert_eq!(iter.next_back(), Some(&mut [0][..]));
     assert_eq!(iter.next(), Some(&mut [3, 3][..]));

library/core/src/slice/iter.rs

@@ -3248,26 +3248,26 @@ unsafe impl<'a, T> TrustedRandomAccessNoCoerce for IterMut<'a, T> {
 
 /// An iterator over slice in (non-overlapping) chunks separated by a predicate.
 ///
-/// This struct is created by the [`group_by`] method on [slices].
+/// This struct is created by the [`chunk_by`] method on [slices].
 ///
-/// [`group_by`]: slice::group_by
+/// [`chunk_by`]: slice::chunk_by
 /// [slices]: slice
-#[unstable(feature = "slice_group_by", issue = "80552")]
+#[stable(feature = "slice_group_by", since = "CURRENT_RUSTC_VERSION")]
 #[must_use = "iterators are lazy and do nothing unless consumed"]
-pub struct GroupBy<'a, T: 'a, P> {
+pub struct ChunkBy<'a, T: 'a, P> {
     slice: &'a [T],
     predicate: P,
 }
 
-#[unstable(feature = "slice_group_by", issue = "80552")]
-impl<'a, T: 'a, P> GroupBy<'a, T, P> {
+#[stable(feature = "slice_group_by", since = "CURRENT_RUSTC_VERSION")]
+impl<'a, T: 'a, P> ChunkBy<'a, T, P> {
     pub(super) fn new(slice: &'a [T], predicate: P) -> Self {
-        GroupBy { slice, predicate }
+        ChunkBy { slice, predicate }
     }
 }
 
-#[unstable(feature = "slice_group_by", issue = "80552")]
-impl<'a, T: 'a, P> Iterator for GroupBy<'a, T, P>
+#[stable(feature = "slice_group_by", since = "CURRENT_RUSTC_VERSION")]
+impl<'a, T: 'a, P> Iterator for ChunkBy<'a, T, P>
 where
     P: FnMut(&T, &T) -> bool,
 {
@@ -3300,8 +3300,8 @@ where
     }
 }
 
-#[unstable(feature = "slice_group_by", issue = "80552")]
-impl<'a, T: 'a, P> DoubleEndedIterator for GroupBy<'a, T, P>
+#[stable(feature = "slice_group_by", since = "CURRENT_RUSTC_VERSION")]
+impl<'a, T: 'a, P> DoubleEndedIterator for ChunkBy<'a, T, P>
 where
     P: FnMut(&T, &T) -> bool,
 {
@@ -3322,39 +3322,39 @@ where
     }
 }
 
-#[unstable(feature = "slice_group_by", issue = "80552")]
-impl<'a, T: 'a, P> FusedIterator for GroupBy<'a, T, P> where P: FnMut(&T, &T) -> bool {}
+#[stable(feature = "slice_group_by", since = "CURRENT_RUSTC_VERSION")]
+impl<'a, T: 'a, P> FusedIterator for ChunkBy<'a, T, P> where P: FnMut(&T, &T) -> bool {}
 
-#[unstable(feature = "slice_group_by", issue = "80552")]
-impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for GroupBy<'a, T, P> {
+#[stable(feature = "slice_group_by", since = "CURRENT_RUSTC_VERSION")]
+impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for ChunkBy<'a, T, P> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("GroupBy").field("slice", &self.slice).finish()
+        f.debug_struct("ChunkBy").field("slice", &self.slice).finish()
     }
 }
 
 /// An iterator over slice in (non-overlapping) mutable chunks separated
 /// by a predicate.
 ///
-/// This struct is created by the [`group_by_mut`] method on [slices].
+/// This struct is created by the [`chunk_by_mut`] method on [slices].
 ///
-/// [`group_by_mut`]: slice::group_by_mut
+/// [`chunk_by_mut`]: slice::chunk_by_mut
 /// [slices]: slice
-#[unstable(feature = "slice_group_by", issue = "80552")]
+#[stable(feature = "slice_group_by", since = "CURRENT_RUSTC_VERSION")]
 #[must_use = "iterators are lazy and do nothing unless consumed"]
-pub struct GroupByMut<'a, T: 'a, P> {
+pub struct ChunkByMut<'a, T: 'a, P> {
     slice: &'a mut [T],
     predicate: P,
 }
 
-#[unstable(feature = "slice_group_by", issue = "80552")]
-impl<'a, T: 'a, P> GroupByMut<'a, T, P> {
+#[stable(feature = "slice_group_by", since = "CURRENT_RUSTC_VERSION")]
+impl<'a, T: 'a, P> ChunkByMut<'a, T, P> {
     pub(super) fn new(slice: &'a mut [T], predicate: P) -> Self {
-        GroupByMut { slice, predicate }
+        ChunkByMut { slice, predicate }
     }
 }
 
-#[unstable(feature = "slice_group_by", issue = "80552")]
-impl<'a, T: 'a, P> Iterator for GroupByMut<'a, T, P>
+#[stable(feature = "slice_group_by", since = "CURRENT_RUSTC_VERSION")]
+impl<'a, T: 'a, P> Iterator for ChunkByMut<'a, T, P>
 where
     P: FnMut(&T, &T) -> bool,
 {
@@ -3388,8 +3388,8 @@ where
     }
 }
 
-#[unstable(feature = "slice_group_by", issue = "80552")]
-impl<'a, T: 'a, P> DoubleEndedIterator for GroupByMut<'a, T, P>
+#[stable(feature = "slice_group_by", since = "CURRENT_RUSTC_VERSION")]
+impl<'a, T: 'a, P> DoubleEndedIterator for ChunkByMut<'a, T, P>
 where
     P: FnMut(&T, &T) -> bool,
 {
@@ -3411,12 +3411,12 @@ where
     }
 }
 
-#[unstable(feature = "slice_group_by", issue = "80552")]
-impl<'a, T: 'a, P> FusedIterator for GroupByMut<'a, T, P> where P: FnMut(&T, &T) -> bool {}
+#[stable(feature = "slice_group_by", since = "CURRENT_RUSTC_VERSION")]
+impl<'a, T: 'a, P> FusedIterator for ChunkByMut<'a, T, P> where P: FnMut(&T, &T) -> bool {}
 
-#[unstable(feature = "slice_group_by", issue = "80552")]
-impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for GroupByMut<'a, T, P> {
+#[stable(feature = "slice_group_by", since = "CURRENT_RUSTC_VERSION")]
+impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for ChunkByMut<'a, T, P> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("GroupByMut").field("slice", &self.slice).finish()
+        f.debug_struct("ChunkByMut").field("slice", &self.slice).finish()
     }
 }