7 files changed, 27 insertions, 14 deletions
diff --git a/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs b/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs
index 78cafe8566b..866736f74a0 100644
--- a/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs
+++ b/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs
@@ -2,7 +2,6 @@ use std::borrow::Cow;
 
 use rustc_abi::Align;
 use rustc_hir::attrs::{InlineAttr, InstructionSetAttr, Linkage, OptimizeAttr};
-use rustc_hir::def_id::DefId;
 use rustc_macros::{HashStable, TyDecodable, TyEncodable};
 use rustc_span::Symbol;
 use rustc_target::spec::SanitizerSet;
@@ -161,6 +160,8 @@ bitflags::bitflags! {
         const ALLOCATOR_ZEROED          = 1 << 14;
         /// `#[no_builtins]`: indicates that disable implicit builtin knowledge of functions for the function.
         const NO_BUILTINS               = 1 << 15;
+        /// Marks foreign items, to make `contains_extern_indicator` cheaper.
+        const FOREIGN_ITEM              = 1 << 16;
     }
 }
 rustc_data_structures::external_bitflags_debug! { CodegenFnAttrFlags }
@@ -194,8 +195,8 @@ impl CodegenFnAttrs {
     /// * `#[linkage]` is present
     ///
     /// Keep this in sync with the logic for the unused_attributes for `#[inline]` lint.
-    pub fn contains_extern_indicator(&self, tcx: TyCtxt<'_>, did: DefId) -> bool {
-        if tcx.is_foreign_item(did) {
+    pub fn contains_extern_indicator(&self) -> bool {
+        if self.flags.contains(CodegenFnAttrFlags::FOREIGN_ITEM) {
             return false;
         }
 
diff --git a/compiler/rustc_middle/src/mir/mono.rs b/compiler/rustc_middle/src/mir/mono.rs
index 533066bdef9..6b45b2dc3ff 100644
--- a/compiler/rustc_middle/src/mir/mono.rs
+++ b/compiler/rustc_middle/src/mir/mono.rs
@@ -149,7 +149,7 @@ impl<'tcx> MonoItem<'tcx> {
         // instantiation:
         // We emit an unused_attributes lint for this case, which should be kept in sync if possible.
         let codegen_fn_attrs = tcx.codegen_instance_attrs(instance.def);
-        if codegen_fn_attrs.contains_extern_indicator(tcx, instance.def.def_id())
+        if codegen_fn_attrs.contains_extern_indicator()
             || codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::NAKED)
         {
             return InstantiationMode::GloballyShared { may_conflict: false };
diff --git a/compiler/rustc_middle/src/mir/query.rs b/compiler/rustc_middle/src/mir/query.rs
index a8a95c699d8..466b9c7a3c2 100644
--- a/compiler/rustc_middle/src/mir/query.rs
+++ b/compiler/rustc_middle/src/mir/query.rs
@@ -149,8 +149,15 @@ pub enum ConstraintCategory<'tcx> {
     /// A constraint that doesn't correspond to anything the user sees.
     Internal,
 
-    /// An internal constraint derived from an illegal universe relation.
-    IllegalUniverse,
+    /// An internal constraint added when a region outlives a placeholder
+    /// it cannot name and therefore has to outlive `'static`. The argument
+    /// is the unnameable placeholder and the constraint is always between
+    /// an SCC representative and `'static`.
+    OutlivesUnnameablePlaceholder(
+        #[type_foldable(identity)]
+        #[type_visitable(ignore)]
+        ty::RegionVid,
+    ),
 }
 
 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
diff --git a/compiler/rustc_middle/src/mir/syntax.rs b/compiler/rustc_middle/src/mir/syntax.rs
index 6039a03aa29..3b8def67f92 100644
--- a/compiler/rustc_middle/src/mir/syntax.rs
+++ b/compiler/rustc_middle/src/mir/syntax.rs
@@ -1371,12 +1371,7 @@ pub enum Rvalue<'tcx> {
 
     /// Creates an array where each element is the value of the operand.
     ///
-    /// This is the cause of a bug in the case where the repetition count is zero because the value
-    /// is not dropped, see [#74836].
-    ///
     /// Corresponds to source code like `[x; 32]`.
-    ///
-    /// [#74836]: https://github.com/rust-lang/rust/issues/74836
     Repeat(Operand<'tcx>, ty::Const<'tcx>),
 
     /// Creates a reference of the indicated kind to the place.
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 01a108c0698..5dbbc7297ab 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -1447,6 +1447,8 @@ pub struct TyCtxt<'tcx> {
 }
 
 impl<'tcx> LintEmitter for TyCtxt<'tcx> {
+    type Id = HirId;
+
     fn emit_node_span_lint(
         self,
         lint: &'static Lint,
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index a7298af502e..e567ba05f61 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -829,14 +829,15 @@ impl<'tcx> OpaqueHiddenType<'tcx> {
         // Convert the type from the function into a type valid outside by mapping generic
         // parameters to into the context of the opaque.
         //
-        // We erase regions when doing this during HIR typeck.
+        // We erase regions when doing this during HIR typeck. We manually use `fold_regions`
+        // here as we do not want to anonymize bound variables.
         let this = match defining_scope_kind {
-            DefiningScopeKind::HirTypeck => tcx.erase_regions(self),
+            DefiningScopeKind::HirTypeck => fold_regions(tcx, self, |_, _| tcx.lifetimes.re_erased),
             DefiningScopeKind::MirBorrowck => self,
         };
         let result = this.fold_with(&mut opaque_types::ReverseMapper::new(tcx, map, self.span));
         if cfg!(debug_assertions) && matches!(defining_scope_kind, DefiningScopeKind::HirTypeck) {
-            assert_eq!(result.ty, tcx.erase_regions(result.ty));
+            assert_eq!(result.ty, fold_regions(tcx, result.ty, |_, _| tcx.lifetimes.re_erased));
         }
         result
     }
diff --git a/compiler/rustc_middle/src/ty/trait_def.rs b/compiler/rustc_middle/src/ty/trait_def.rs
index 59e2b2a034d..4e38d969192 100644
--- a/compiler/rustc_middle/src/ty/trait_def.rs
+++ b/compiler/rustc_middle/src/ty/trait_def.rs
@@ -6,6 +6,7 @@ use rustc_hir as hir;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
 use rustc_macros::{Decodable, Encodable, HashStable};
+use rustc_span::symbol::sym;
 use tracing::debug;
 
 use crate::query::LocalCrate;
@@ -239,6 +240,12 @@ pub(super) fn trait_impls_of_provider(tcx: TyCtxt<'_>, trait_id: DefId) -> Trait
 
 /// Query provider for `incoherent_impls`.
 pub(super) fn incoherent_impls_provider(tcx: TyCtxt<'_>, simp: SimplifiedType) -> &[DefId] {
+    if let Some(def_id) = simp.def()
+        && !tcx.has_attr(def_id, sym::rustc_has_incoherent_inherent_impls)
+    {
+        return &[];
+    }
+
     let mut impls = Vec::new();
     for cnum in iter::once(LOCAL_CRATE).chain(tcx.crates(()).iter().copied()) {
         for &impl_def_id in tcx.crate_incoherent_impls((cnum, simp)) {