Rollup of 25 pull requests

.git-blame-ignore-revs

@@ -33,3 +33,6 @@ c682aa162b0d41e21cc6748f4fecfe01efb69d1f
 1fcae03369abb4c2cc180cd5a49e1f4440a81300
 # Breaking up of compiletest runtest.rs
 60600a6fa403216bfd66e04f948b1822f6450af7
+
+# std: move futex implementations into sys::sync::futex
+7232830d10b6af772e0e4670a2ff61dd23830ed8

.github/pull_request_template.md

@@ -1,5 +1,16 @@
 <!-- homu-ignore:start -->
+
+- [ ] I did not use an LLM to create a change in this PR.
+- [ ] I used an LLM to create a change in this PR, and I have explained below how it was used.
+
 <!--
+Please read our [LLM policy] before opening a PR,
+and check one of the boxes above to indicate whether you've used an LLM.
+If you do not check a box, a reviewer may ask you whether an LLM was involved.
+LLM contributions are not banned, but are held to a higher standard of review and correctness.
+
+[LLM policy]: https://forge.rust-lang.org/policies/llm-usage.html
+
 If this PR is related to an unstable feature or an otherwise tracked effort,
 please link to the relevant tracking issue here. If you don't know of a related
 tracking issue or there are none, feel free to ignore this.

CONTRIBUTING.md

@@ -29,6 +29,15 @@ that you read and understand the [rustc-dev-guide] before making a contribution.
 talks about the different bots in the Rust ecosystem, the Rust development tools,
 bootstrapping, the compiler architecture, source code representation, and more.
 
+## LLM policy
+
+We have a policy for how LLMs are allowed to be used in contributions to `rust-lang/rust`.
+You can read it [on Forge][LLM policy].
+For suggestions about how to use LLMs *well*, and how to review LLM-created PRs, see [the dev-guide][llm-guidance].
+
+[LLM policy]: https://forge.rust-lang.org/policies/llm-usage.html
+[llm-guidance]: https://rustc-dev-guide.rust-lang.org/llm-guidance.html
+
 ## [Getting help](https://rustc-dev-guide.rust-lang.org/getting-started.html#asking-questions)
 
 There are many ways you can get help when you're stuck. Rust has two platforms for this:

Cargo.lock

@@ -3954,6 +3954,7 @@ dependencies = [
  "rustc_errors",
  "rustc_expand",
  "rustc_feature",
+ "rustc_hir",
  "rustc_hir_analysis",
  "rustc_hir_pretty",
  "rustc_index",
@@ -4414,7 +4415,6 @@ dependencies = [
  "rustc_graphviz",
  "rustc_hashes",
  "rustc_hir",
- "rustc_hir_pretty",
  "rustc_index",
  "rustc_lint_defs",
  "rustc_macros",
@@ -4621,7 +4621,7 @@ dependencies = [
  "rustc_middle",
  "rustc_session",
  "rustc_span",
- "rustc_ty_utils",
+ "rustc_ty_walk",
  "tracing",
 ]
 
@@ -4908,6 +4908,17 @@ dependencies = [
  "rustc_span",
  "rustc_target",
  "rustc_trait_selection",
+ "rustc_ty_walk",
+ "tracing",
+]
+
+[[package]]
+name = "rustc_ty_walk"
+version = "0.0.0"
+dependencies = [
+ "rustc_hir",
+ "rustc_middle",
+ "rustc_span",
  "tracing",
 ]
 

compiler/rustc_abi/src/tests.rs

@@ -6,6 +6,68 @@ fn align_constants() {
     assert_eq!(Align::EIGHT, Align::from_bytes(8).unwrap());
 }
 
+#[test]
+#[should_panic(expected = "Value 299 is too big for Size(1 bytes)")]
+fn wrapping_range_smallest_range_containing_size_mismatch() {
+    WrappingRange::smallest_range_containing(200..300, Size::from_bytes(1));
+}
+
+#[test]
+fn wrapping_range_smallest_range_containing() {
+    #[track_caller]
+    fn check(x: impl IntoIterator<Item = u128>, bytes: u64, start: u128, end: u128) {
+        assert_eq!(
+            WrappingRange::smallest_range_containing(x, Size::from_bytes(bytes)),
+            Some(WrappingRange { start, end }),
+        );
+    }
+
+    assert_eq!(WrappingRange::smallest_range_containing([], Size::from_bytes(1)), None);
+
+    check([7], 1, 7, 7);
+    check([7, 7, 7], 1, 7, 7);
+
+    check(0..=127, 1, 0, 127);
+    check((0..=127).chain([255]), 1, 255, 127);
+
+    check((-100..=100_i128).map(i128::cast_unsigned), 16, (-100_i128).cast_unsigned(), 100);
+
+    // A wraparound case that's not just "sort them as signed"
+    check([10, 100, 160, 220], 1, 100, 10);
+
+    check([0, 0xFF], 1, 0xFF, 0);
+    check([0, 0xFF], 2, 0, 0xFF);
+    check([0, 0xFFFF], 2, 0xFFFF, 0);
+    check([0, 0xFFFF], 4, 0, 0xFFFF);
+    check([0, 0xFFFFFFFF], 4, 0xFFFFFFFF, 0);
+    check([0, 0xFFFFFFFF], 8, 0, 0xFFFFFFFF);
+
+    check([100, 200], 1, 100, 200);
+    check([100, 200, 50], 1, 50, 200);
+    check([100, 200, 250], 1, 100, 250);
+    check([100, 200, 250, 50], 1, 200, 100);
+
+    check([200, 50], 1, 200, 50);
+    check([200, 50, 190], 1, 190, 50);
+    check([200, 50, 60], 1, 200, 60);
+    check([200, 50, 125], 1, 50, 200);
+
+    // The mem::Alignment case
+    check((0..64).map(|n| 1 << n), 8, 1, i64::MIN.cast_unsigned().into());
+
+    // Both `100..=228` and `..=228 | 100..` are the same size, but we pick the one without zero.
+    check([100, 228], 1, 100, 228);
+
+    // The wraparound one here is slightly smaller, so we pick it despite including zero.
+    // (The distance 10→96 is 86, compared to 85 for 96→181 and 181→10.)
+    check([10, 96, 181], 1, 96, 10);
+
+    // These 4 values are evenly spaced so all 4 candidate ranges have length 193:
+    // `(..=32) | (96..)`, `(..=96) | (160..)`, `(..=160) | (224..)`, and `32..=224`.
+    // We pick the last one as the only one that doesn't contain zero.
+    check([0xA0, 0xE0, 0x20, 0x60], 1, 0x20, 0xE0);
+}
+
 #[test]
 fn wrapping_range_contains_range() {
     let size16 = Size::from_bytes(16);

compiler/rustc_abi/src/wrapping_range.rs

@@ -1,5 +1,5 @@
-use std::fmt;
 use std::ops::RangeFull;
+use std::{fmt, iter};
 
 use crate::Size;
 #[cfg(feature = "nightly")]
@@ -149,51 +149,49 @@ impl WrappingRange {
     ///
     /// # Examples
     ///
-    ///
     /// ```
     /// use rustc_abi::{Size, WrappingRange};
     ///
-    /// let range = WrappingRange::smallest_range_containing([2, 6, 12, 4], Size::from_bytes(2));
-    /// assert_eq!(range.unwrap(), WrappingRange { start: 2, end: 12 });
+    /// let chain = std::iter::chain(10..20, 30..40);
+    /// let range = WrappingRange::smallest_range_containing(chain, Size::from_bytes(2));
+    /// assert_eq!(range.unwrap(), WrappingRange { start: 10, end: 39 });
     ///
-    /// let range = WrappingRange::smallest_range_containing(0..=127, Size::from_bytes(1));
-    /// assert_eq!(range.unwrap(), WrappingRange { start: 0, end: 127 });
-    /// let range = WrappingRange::smallest_range_containing([129, 128, 127], Size::from_bytes(1));
-    /// assert_eq!(range.unwrap(), WrappingRange { start: 127, end: 129 });
+    /// // Values don't need to be sorted nor unique
+    /// let range = WrappingRange::smallest_range_containing([3, 5, 3, 1, 3], Size::from_bytes(2));
+    /// assert_eq!(range.unwrap(), WrappingRange { start: 1, end: 5 });
     ///
     /// // The size matters because it changes where the wrapping can happen:
     /// let range = WrappingRange::smallest_range_containing([1, 254], Size::from_bytes(1));
     /// assert_eq!(range.unwrap(), WrappingRange { start: 254, end: 1 });
     /// let range = WrappingRange::smallest_range_containing([1, 254], Size::from_bytes(4));
     /// assert_eq!(range.unwrap(), WrappingRange { start: 1, end: 254 });
-    ///
-    /// // Both `100..=228` and `..=228 | 100..` are the same size, but we pick the one without zero.
-    /// let range = WrappingRange::smallest_range_containing([100, 228], Size::from_bytes(1));
-    /// assert_eq!(range.unwrap(), WrappingRange { start: 100, end: 228 });
-    /// // These 4 values are evenly spaced so all 4 candidate ranges have length 193:
-    /// // `(..=32) | (96..)`, `(..=96) | (160..)`, `(..=160) | (224..)`, and `32..=224`.
-    /// // We pick the last one as the only one that doesn't contain zero.
-    /// let range = WrappingRange::smallest_range_containing([0xA0, 0xE0, 0x20, 0x60], Size::from_bytes(1));
-    /// assert_eq!(range.unwrap(), WrappingRange { start: 0x20, end: 0xE0 });
     /// ```
     pub fn smallest_range_containing(
         values: impl IntoIterator<Item = u128>,
         size: Size,
     ) -> Option<Self> {
         let mut values: Vec<_> = values.into_iter().collect();
-        let umax = size.unsigned_int_max();
-        for value in &values {
-            debug_assert!(*value <= umax, "Value {value:?} is too big for {size:?}");
-        }
         values.sort_unstable();
 
-        // Having sorted all the values, every element is a possible start point for the
-        // range of values, up to the previous element (wrapping around the end of the vec).
-        // Look at all those candidates and pick the one that's as narrow as possible.
-        let pairs = std::iter::zip(values.iter().copied(), values.iter().copied().cycle().skip(1));
-        let ranges = pairs.map(|(end, start)| WrappingRange { start, end });
-        let smallest_range = ranges.min_by_key(|r| (r.width(size), r.start));
-        smallest_range
+        // The simple answer is the non-wraparound range `min..=max`.
+        let obvious_range = WrappingRange { start: *values.first()?, end: *values.last()? };
+
+        // Having sorted the inputs, one test is enough to double-check they all fit in `size`.
+        let max_input = obvious_range.end;
+        assert!(
+            max_input <= size.unsigned_int_max(),
+            "Value {max_input:?} is too big for {size:?}",
+        );
+
+        // But every `[.., end, start, ..]` is also a potential candidate for a wraparound
+        // range `(..=end) | (start..)`, so long as `start` and `end` aren't duplicates.
+        let wraparound_ranges = values
+            .array_windows::<2>()
+            .filter_map(|&[end, start]| (start != end).then_some(WrappingRange { start, end }));
+
+        // Pick whichever range is smallest. By putting the non-wraparound range first,
+        // it'll be preferred over a wraparound range with the same width.
+        iter::chain(iter::once(obvious_range), wraparound_ranges).min_by_key(|r| r.width(size))
     }
 }
 

compiler/rustc_attr_parsing/src/attributes/traits.rs

@@ -3,6 +3,7 @@ use std::mem;
 use rustc_feature::AttributeStability;
 
 use super::prelude::*;
+use crate::AttributeSafety;
 use crate::attributes::{NoArgsAttributeParser, SingleAttributeParser};
 use crate::context::AcceptContext;
 use crate::parser::ArgParser;
@@ -98,12 +99,18 @@ impl NoArgsAttributeParser for RustcSpecializationTraitParser {
     const CREATE: fn(Span) -> AttributeKind = |_| AttributeKind::RustcSpecializationTrait;
 }
 
-pub(crate) struct RustcUnsafeSpecializationMarkerParser;
-impl NoArgsAttributeParser for RustcUnsafeSpecializationMarkerParser {
-    const PATH: &[Symbol] = &[sym::rustc_unsafe_specialization_marker];
+pub(crate) struct RustcAllowLifetimeDependentSpecializationParser;
+impl NoArgsAttributeParser for RustcAllowLifetimeDependentSpecializationParser {
+    const PATH: &[Symbol] = &[sym::rustc_allow_lifetime_dependent_specialization];
     const ALLOWED_TARGETS: AllowedTargets<'_> = AllowedTargets::AllowList(&[Allow(Target::Trait)]);
     const STABILITY: AttributeStability = unstable!(rustc_attrs);
-    const CREATE: fn(Span) -> AttributeKind = |_| AttributeKind::RustcUnsafeSpecializationMarker;
+    const CREATE: fn(Span) -> AttributeKind =
+        |_| AttributeKind::RustcAllowLifetimeDependentSpecialization;
+    const SAFETY: AttributeSafety = AttributeSafety::Unsafe {
+        note: "this attribute requires `unsafe` because lifetime constraints from \
+            the implementations of the trait are not considered when specializing",
+        unsafe_since: None,
+    };
 }
 
 // Coherence

compiler/rustc_attr_parsing/src/context.rs

@@ -295,6 +295,7 @@ attribute_parsers!(
         Single<WithoutArgs<RustcAllocatorParser>>,
         Single<WithoutArgs<RustcAllocatorZeroedParser>>,
         Single<WithoutArgs<RustcAllowIncoherentImplParser>>,
+        Single<WithoutArgs<RustcAllowLifetimeDependentSpecializationParser>>,
         Single<WithoutArgs<RustcAsPtrParser>>,
         Single<WithoutArgs<RustcCanonicalSymbolParser>>,
         Single<WithoutArgs<RustcCaptureAnalysisParser>>,
@@ -355,7 +356,6 @@ attribute_parsers!(
         Single<WithoutArgs<RustcStrictCoherenceParser>>,
         Single<WithoutArgs<RustcTestEntrypointMarkerParser>>,
         Single<WithoutArgs<RustcTrivialFieldReadsParser>>,
-        Single<WithoutArgs<RustcUnsafeSpecializationMarkerParser>>,
         Single<WithoutArgs<SplatParser>>,
         Single<WithoutArgs<ThreadLocalParser>>,
         Single<WithoutArgs<TrackCallerParser>>,

compiler/rustc_attr_parsing/src/parser.rs

@@ -489,7 +489,7 @@ fn expr_to_lit<'sess>(
     }
 }
 
-/// Whether expansions of `expr` metavariables from decrarative macros
+/// Whether expansions of `expr` metavariables from declarative  macros
 /// are permitted. Used when parsing meta items; currently, only `cfg` predicates
 /// enable this option
 #[derive(Clone, Copy, PartialEq, Eq)]

compiler/rustc_borrowck/src/lib.rs

@@ -304,7 +304,7 @@ struct CollectRegionConstraintsResult<'tcx> {
     location_map: Rc<DenseLocationMap>,
     universal_region_relations: Frozen<UniversalRegionRelations<'tcx>>,
     region_bound_pairs: Frozen<RegionBoundPairs<'tcx>>,
-    known_type_outlives_obligations: Frozen<Vec<ty::PolyTypeOutlivesPredicate<'tcx>>>,
+    known_type_outlives_obligations: Frozen<Vec<ty::PolyTypeOutlivesClause<'tcx>>>,
     constraints: MirTypeckRegionConstraints<'tcx>,
     deferred_closure_requirements: DeferredClosureRequirements<'tcx>,
     deferred_opaque_type_errors: Vec<DeferredOpaqueTypeError<'tcx>>,

compiler/rustc_borrowck/src/region_infer/opaque_types/mod.rs

@@ -531,7 +531,7 @@ pub(crate) fn apply_definition_site_hidden_types<'tcx>(
     body: &Body<'tcx>,
     universal_regions: &UniversalRegions<'tcx>,
     region_bound_pairs: &RegionBoundPairs<'tcx>,
-    known_type_outlives_obligations: &[ty::PolyTypeOutlivesPredicate<'tcx>],
+    known_type_outlives_obligations: &[ty::PolyTypeOutlivesClause<'tcx>],
     constraints: &mut MirTypeckRegionConstraints<'tcx>,
     hidden_types: &mut FxIndexMap<LocalDefId, ty::DefinitionSiteHiddenType<'tcx>>,
     opaque_types: &[(OpaqueTypeKey<'tcx>, ProvisionalHiddenType<'tcx>)],

compiler/rustc_borrowck/src/type_check/canonical.rs

@@ -24,7 +24,7 @@ pub(crate) fn fully_perform_op_raw<'tcx, R: fmt::Debug, Op>(
     body: &Body<'tcx>,
     universal_regions: &UniversalRegions<'tcx>,
     region_bound_pairs: &RegionBoundPairs<'tcx>,
-    known_type_outlives_obligations: &[ty::PolyTypeOutlivesPredicate<'tcx>],
+    known_type_outlives_obligations: &[ty::PolyTypeOutlivesClause<'tcx>],
     constraints: &mut MirTypeckRegionConstraints<'tcx>,
     locations: Locations,
     category: ConstraintCategory<'tcx>,

compiler/rustc_borrowck/src/type_check/constraint_conversion.rs

@@ -34,7 +34,7 @@ pub(crate) struct ConstraintConversion<'a, 'tcx> {
     /// logic expecting to see (e.g.) `ReStatic`, and if we supplied
     /// our special inference variable there, we would mess that up.
     region_bound_pairs: &'a RegionBoundPairs<'tcx>,
-    known_type_outlives_obligations: &'a [ty::PolyTypeOutlivesPredicate<'tcx>],
+    known_type_outlives_obligations: &'a [ty::PolyTypeOutlivesClause<'tcx>],
     locations: Locations,
     span: Span,
     category: ConstraintCategory<'tcx>,
@@ -47,7 +47,7 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
         infcx: &'a BorrowckInferCtxt<'tcx>,
         universal_regions: &'a UniversalRegions<'tcx>,
         region_bound_pairs: &'a RegionBoundPairs<'tcx>,
-        known_type_outlives_obligations: &'a [ty::PolyTypeOutlivesPredicate<'tcx>],
+        known_type_outlives_obligations: &'a [ty::PolyTypeOutlivesClause<'tcx>],
         locations: Locations,
         span: Span,
         category: ConstraintCategory<'tcx>,
@@ -115,7 +115,7 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
             self.category = outlives_requirement.category;
             self.span = outlives_requirement.blame_span;
             self.convert(
-                ty::OutlivesPredicate(subject, outlived_region),
+                ty::OutlivesClause(subject, outlived_region),
                 self.category,
                 &Default::default(),
             );
@@ -125,9 +125,9 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
 
     fn convert(
         &mut self,
-        predicate: ty::ArgOutlivesPredicate<'tcx>,
+        clause: ty::ArgOutlivesClause<'tcx>,
         constraint_category: ConstraintCategory<'tcx>,
-        higher_ranked_assumptions: &FxHashSet<ty::ArgOutlivesPredicate<'tcx>>,
+        higher_ranked_assumptions: &FxHashSet<ty::ArgOutlivesClause<'tcx>>,
     ) {
         let tcx = self.infcx.tcx;
         debug!("generate: constraints at: {:#?}", self.locations);
@@ -141,15 +141,14 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
             ..
         } = *self;
 
-        let pred = predicate;
         // Constraint is implied by a coroutine's well-formedness.
         if self.infcx.tcx.sess.opts.unstable_opts.higher_ranked_assumptions
-            && higher_ranked_assumptions.contains(&pred)
+            && higher_ranked_assumptions.contains(&clause)
         {
             return;
         }
 
-        let ty::OutlivesPredicate(k1, r2) = pred;
+        let ty::OutlivesClause(k1, r2) = clause;
         match k1.kind() {
             GenericArgKind::Lifetime(r1) => {
                 let r1_vid = self.to_region_vid(r1);