Auto merge of #129595 - matthiaskrgr:rollup-4udn7nn, r=matthiaskrgr

Rollup of 9 pull requests

Successful merges:

 - #129288 (Use subtyping for `UnsafeFnPointer` coercion, too)
 - #129405 (Fixing span manipulation and indentation of the suggestion introduced by #126187)
 - #129518 (gitignore: ignore ICE reports regardless of directory)
 - #129519 (Remove redundant flags from `lower_ty_common` that can be inferred from the HIR)
 - #129525 (rustdoc: clean up tuple <-> primitive conversion docs)
 - #129526 (Use `FxHasher` on new solver unconditionally)
 - #129544 (Removes dead code from the compiler)
 - #129553 (add back test for stable-const-can-only-call-stable-const)
 - #129590 (Avoid taking reference of &TyKind)

r? `@ghost`
`@rustbot` modify labels: rollup

.gitignore

@@ -56,7 +56,9 @@ build/
 /src/tools/x/target
 # Created by default with `src/ci/docker/run.sh`
 /obj/
-/rustc-ice*
+
+## ICE reports
+rustc-ice-*.txt
 
 ## Temporary files
 *~

Cargo.lock

@@ -4536,6 +4536,7 @@ dependencies = [
  "bitflags 2.6.0",
  "derive-where",
  "indexmap",
+ "rustc-hash",
  "rustc_ast_ir",
  "rustc_data_structures",
  "rustc_index",

compiler/rustc_borrowck/src/borrowck_errors.rs

@@ -290,7 +290,7 @@ impl<'infcx, 'tcx> crate::MirBorrowckCtxt<'_, '_, 'infcx, 'tcx> {
         ty: Ty<'_>,
         is_index: Option<bool>,
     ) -> Diag<'infcx> {
-        let type_name = match (&ty.kind(), is_index) {
+        let type_name = match (ty.kind(), is_index) {
             (&ty::Array(_, _), Some(true)) | (&ty::Array(_, _), None) => "array",
             (&ty::Slice(_), _) => "slice",
             _ => span_bug!(move_from_span, "this path should not cause illegal move"),

compiler/rustc_borrowck/src/places_conflict.rs

@@ -201,7 +201,7 @@ fn place_components_conflict<'tcx>(
 
             let base_ty = base.ty(body, tcx).ty;
 
-            match (elem, &base_ty.kind(), access) {
+            match (elem, base_ty.kind(), access) {
                 (_, _, Shallow(Some(ArtificialField::ArrayLength)))
                 | (_, _, Shallow(Some(ArtificialField::FakeBorrow))) => {
                     // The array length is like additional fields on the

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -2043,9 +2043,9 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
 
                         let ty_fn_ptr_from = tcx.safe_to_unsafe_fn_ty(fn_sig);
 
-                        if let Err(terr) = self.eq_types(
+                        if let Err(terr) = self.sub_types(
-                            *ty,
                             ty_fn_ptr_from,
+                            *ty,
                             location.to_locations(),
                             ConstraintCategory::Cast { unsize_to: None },
                         ) {

compiler/rustc_const_eval/messages.ftl

@@ -419,7 +419,7 @@ const_eval_unstable_const_fn = `{$def_path}` is not yet stable as a const fn
 const_eval_unstable_in_stable =
     const-stable function cannot use `#[feature({$gate})]`
     .unstable_sugg = if it is not part of the public API, make this function unstably const
-    .bypass_sugg = otherwise `#[rustc_allow_const_fn_unstable]` can be used to bypass stability checks
+    .bypass_sugg = otherwise `#[rustc_allow_const_fn_unstable]` can be used to bypass stability checks (but requires team approval)
 
 const_eval_unterminated_c_string =
     reading a null-terminated string starting at {$pointer} with no null found before end of allocation

compiler/rustc_const_eval/src/interpret/cast.rs

@@ -388,7 +388,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         let (src_pointee_ty, dest_pointee_ty) =
             self.tcx.struct_lockstep_tails_for_codegen(source_ty, cast_ty, self.param_env);
 
-        match (&src_pointee_ty.kind(), &dest_pointee_ty.kind()) {
+        match (src_pointee_ty.kind(), dest_pointee_ty.kind()) {
             (&ty::Array(_, length), &ty::Slice(_)) => {
                 let ptr = self.read_pointer(src)?;
                 let val = Immediate::new_slice(
@@ -478,9 +478,9 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         dest: &PlaceTy<'tcx, M::Provenance>,
     ) -> InterpResult<'tcx> {
         trace!("Unsizing {:?} of type {} into {}", *src, src.layout.ty, cast_ty.ty);
-        match (&src.layout.ty.kind(), &cast_ty.ty.kind()) {
+        match (src.layout.ty.kind(), cast_ty.ty.kind()) {
             (&ty::Ref(_, s, _), &ty::Ref(_, c, _) | &ty::RawPtr(c, _))
-            | (&ty::RawPtr(s, _), &ty::RawPtr(c, _)) => self.unsize_into_ptr(src, dest, *s, *c),
+            | (&ty::RawPtr(s, _), &ty::RawPtr(c, _)) => self.unsize_into_ptr(src, dest, s, c),
             (&ty::Adt(def_a, _), &ty::Adt(def_b, _)) => {
                 assert_eq!(def_a, def_b); // implies same number of fields
 

compiler/rustc_hir_analysis/src/collect.rs

@@ -392,7 +392,7 @@ impl<'tcx> HirTyLowerer<'tcx> for ItemCtxt<'tcx> {
     }
 
     fn re_infer(&self, span: Span, reason: RegionInferReason<'_>) -> ty::Region<'tcx> {
-        if let RegionInferReason::BorrowedObjectLifetimeDefault = reason {
+        if let RegionInferReason::ObjectLifetimeDefault = reason {
             let e = struct_span_code_err!(
                 self.dcx(),
                 span,

compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs

@@ -608,7 +608,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
 
         let mut bound_span_label = |self_ty: Ty<'_>, obligation: &str, quiet: &str| {
             let msg = format!("`{}`", if obligation.len() > 50 { quiet } else { obligation });
-            match &self_ty.kind() {
+            match self_ty.kind() {
                 // Point at the type that couldn't satisfy the bound.
                 ty::Adt(def, _) => {
                     bound_spans.get_mut_or_insert_default(tcx.def_span(def.did())).push(msg)

compiler/rustc_hir_analysis/src/hir_ty_lowering/lint.rs

@@ -15,11 +15,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
     ///
     /// *Bare* trait object types are ones that aren't preceded by the keyword `dyn`.
     /// In edition 2021 and onward we emit a hard error for them.
-    pub(super) fn prohibit_or_lint_bare_trait_object_ty(
+    pub(super) fn prohibit_or_lint_bare_trait_object_ty(&self, self_ty: &hir::Ty<'_>) {
-        &self,
-        self_ty: &hir::Ty<'_>,
-        in_path: bool,
-    ) {
         let tcx = self.tcx();
 
         let hir::TyKind::TraitObject([poly_trait_ref, ..], _, TraitObjectSyntax::None) =
@@ -28,6 +24,21 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             return;
         };
 
+        let in_path = match tcx.parent_hir_node(self_ty.hir_id) {
+            hir::Node::Ty(hir::Ty {
+                kind: hir::TyKind::Path(hir::QPath::TypeRelative(qself, _)),
+                ..
+            })
+            | hir::Node::Expr(hir::Expr {
+                kind: hir::ExprKind::Path(hir::QPath::TypeRelative(qself, _)),
+                ..
+            })
+            | hir::Node::Pat(hir::Pat {
+                kind: hir::PatKind::Path(hir::QPath::TypeRelative(qself, _)),
+                ..
+            }) if qself.hir_id == self_ty.hir_id => true,
+            _ => false,
+        };
         let needs_bracket = in_path
             && !tcx
                 .sess

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

@@ -85,10 +85,9 @@ pub enum PredicateFilter {
 
 #[derive(Debug)]
 pub enum RegionInferReason<'a> {
-    /// Lifetime on a trait object behind a reference.
+    /// Lifetime on a trait object that is spelled explicitly, e.g. `+ 'a` or `+ '_`.
-    /// This allows inferring information from the reference.
+    ExplicitObjectLifetime,
-    BorrowedObjectLifetimeDefault,
+    /// A trait object's lifetime when it is elided, e.g. `dyn Any`.
-    /// A trait object's lifetime.
     ObjectLifetimeDefault,
     /// Generic lifetime parameter
     Param(&'a ty::GenericParamDef),
@@ -1057,7 +1056,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
 
         // Find the type of the associated item, and the trait where the associated
         // item is declared.
-        let bound = match (&qself_ty.kind(), qself_res) {
+        let bound = match (qself_ty.kind(), qself_res) {
             (_, Res::SelfTyAlias { alias_to: impl_def_id, is_trait_impl: true, .. }) => {
                 // `Self` in an impl of a trait -- we have a concrete self type and a
                 // trait reference.
@@ -1999,16 +1998,6 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         }
     }
 
-    /// Lower a type from the HIR to our internal notion of a type.
-    pub fn lower_ty(&self, hir_ty: &hir::Ty<'tcx>) -> Ty<'tcx> {
-        self.lower_ty_common(hir_ty, false, false)
-    }
-
-    /// Lower a type inside of a path from the HIR to our internal notion of a type.
-    pub fn lower_ty_in_path(&self, hir_ty: &hir::Ty<'tcx>) -> Ty<'tcx> {
-        self.lower_ty_common(hir_ty, false, true)
-    }
-
     fn lower_delegation_ty(&self, idx: hir::InferDelegationKind) -> Ty<'tcx> {
         let delegation_sig = self.tcx().inherit_sig_for_delegation_item(self.item_def_id());
         match idx {
@@ -2026,7 +2015,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
     /// 2. `in_path`: Whether the type appears inside of a path.
     ///    Used to provide correct diagnostics for bare trait object types.
     #[instrument(level = "debug", skip(self), ret)]
-    fn lower_ty_common(&self, hir_ty: &hir::Ty<'tcx>, borrowed: bool, in_path: bool) -> Ty<'tcx> {
+    pub fn lower_ty(&self, hir_ty: &hir::Ty<'tcx>) -> Ty<'tcx> {
         let tcx = self.tcx();
 
         let result_ty = match &hir_ty.kind {
@@ -2036,7 +2025,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             hir::TyKind::Ref(region, mt) => {
                 let r = self.lower_lifetime(region, RegionInferReason::Reference);
                 debug!(?r);
-                let t = self.lower_ty_common(mt.ty, true, false);
+                let t = self.lower_ty(mt.ty);
                 Ty::new_ref(tcx, r, t, mt.mutbl)
             }
             hir::TyKind::Never => tcx.types.never,
@@ -2065,20 +2054,13 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 )
             }
             hir::TyKind::TraitObject(bounds, lifetime, repr) => {
-                self.prohibit_or_lint_bare_trait_object_ty(hir_ty, in_path);
+                self.prohibit_or_lint_bare_trait_object_ty(hir_ty);
 
                 let repr = match repr {
                     TraitObjectSyntax::Dyn | TraitObjectSyntax::None => ty::Dyn,
                     TraitObjectSyntax::DynStar => ty::DynStar,
                 };
-                self.lower_trait_object_ty(
+                self.lower_trait_object_ty(hir_ty.span, hir_ty.hir_id, bounds, lifetime, repr)
-                    hir_ty.span,
-                    hir_ty.hir_id,
-                    bounds,
-                    lifetime,
-                    borrowed,
-                    repr,
-                )
             }
             hir::TyKind::Path(hir::QPath::Resolved(maybe_qself, path)) => {
                 debug!(?maybe_qself, ?path);
@@ -2106,7 +2088,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             }
             hir::TyKind::Path(hir::QPath::TypeRelative(qself, segment)) => {
                 debug!(?qself, ?segment);
-                let ty = self.lower_ty_common(qself, false, true);
+                let ty = self.lower_ty(qself);
                 self.lower_assoc_path(hir_ty.hir_id, hir_ty.span, ty, qself, segment, false)
                     .map(|(ty, _, _)| ty)
                     .unwrap_or_else(|guar| Ty::new_error(tcx, guar))

compiler/rustc_hir_analysis/src/hir_ty_lowering/object_safety.rs

@@ -30,7 +30,6 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         hir_id: hir::HirId,
         hir_trait_bounds: &[(hir::PolyTraitRef<'tcx>, hir::TraitBoundModifier)],
         lifetime: &hir::Lifetime,
-        borrowed: bool,
         representation: DynKind,
     ) -> Ty<'tcx> {
         let tcx = self.tcx();
@@ -325,22 +324,32 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         v.dedup();
         let existential_predicates = tcx.mk_poly_existential_predicates(&v);
 
-        // Use explicitly-specified region bound.
+        // Use explicitly-specified region bound, unless the bound is missing.
         let region_bound = if !lifetime.is_elided() {
-            self.lower_lifetime(lifetime, RegionInferReason::ObjectLifetimeDefault)
+            self.lower_lifetime(lifetime, RegionInferReason::ExplicitObjectLifetime)
         } else {
             self.compute_object_lifetime_bound(span, existential_predicates).unwrap_or_else(|| {
+                // Curiously, we prefer object lifetime default for `+ '_`...
                 if tcx.named_bound_var(lifetime.hir_id).is_some() {
-                    self.lower_lifetime(lifetime, RegionInferReason::ObjectLifetimeDefault)
+                    self.lower_lifetime(lifetime, RegionInferReason::ExplicitObjectLifetime)
                 } else {
-                    self.re_infer(
+                    let reason =
-                        span,
+                        if let hir::LifetimeName::ImplicitObjectLifetimeDefault = lifetime.res {
-                        if borrowed {
+                            if let hir::Node::Ty(hir::Ty {
-                            RegionInferReason::ObjectLifetimeDefault
+                                kind: hir::TyKind::Ref(parent_lifetime, _),
+                                ..
+                            }) = tcx.parent_hir_node(hir_id)
+                                && tcx.named_bound_var(parent_lifetime.hir_id).is_none()
+                            {
+                                // Parent lifetime must have failed to resolve. Don't emit a redundant error.
+                                RegionInferReason::ExplicitObjectLifetime
+                            } else {
+                                RegionInferReason::ObjectLifetimeDefault
+                            }
                         } else {
-                            RegionInferReason::BorrowedObjectLifetimeDefault
+                            RegionInferReason::ExplicitObjectLifetime
-                        },
+                        };
-                    )
+                    self.re_infer(span, reason)
                 }
             })
         };

compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs

@@ -798,7 +798,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 // to be object-safe.
                 // We manually call `register_wf_obligation` in the success path
                 // below.
-                let ty = self.lowerer().lower_ty_in_path(qself);
+                let ty = self.lowerer().lower_ty(qself);
                 (LoweredTy::from_raw(self, span, ty), qself, segment)
             }
             QPath::LangItem(..) => {

compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs

@@ -2975,7 +2975,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let mut suffix_suggestion = sugg.clone();
         suffix_suggestion.push((
             if matches!(
-                (&expected_ty.kind(), &checked_ty.kind()),
+                (expected_ty.kind(), checked_ty.kind()),
                 (ty::Int(_) | ty::Uint(_), ty::Float(_))
             ) {
                 // Remove fractional part from literal, for example `42.0f32` into `42`
@@ -3077,7 +3077,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 err.multipart_suggestion_verbose(msg, suggestion, Applicability::MachineApplicable);
             };
 
-        match (&expected_ty.kind(), &checked_ty.kind()) {
+        match (expected_ty.kind(), checked_ty.kind()) {
             (ty::Int(exp), ty::Int(found)) => {
                 let (f2e_is_fallible, e2f_is_fallible) = match (exp.bit_width(), found.bit_width())
                 {

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -1012,7 +1012,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 };
             let mut bound_span_label = |self_ty: Ty<'_>, obligation: &str, quiet: &str| {
                 let msg = format!("`{}`", if obligation.len() > 50 { quiet } else { obligation });
-                match &self_ty.kind() {
+                match self_ty.kind() {
                     // Point at the type that couldn't satisfy the bound.
                     ty::Adt(def, _) => {
                         bound_spans.get_mut_or_insert_default(tcx.def_span(def.did())).push(msg)

compiler/rustc_hir_typeck/src/pat.rs

@@ -1336,7 +1336,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         // More generally, the expected type wants a tuple variant with one field of an
         // N-arity-tuple, e.g., `V_i((p_0, .., p_N))`. Meanwhile, the user supplied a pattern
         // with the subpatterns directly in the tuple variant pattern, e.g., `V_i(p_0, .., p_N)`.
-        let missing_parentheses = match (&expected.kind(), fields, had_err) {
+        let missing_parentheses = match (expected.kind(), fields, had_err) {
             // #67037: only do this if we could successfully type-check the expected type against
             // the tuple struct pattern. Otherwise the args could get out of range on e.g.,
             // `let P() = U;` where `P != U` with `struct P<T>(T);`.

compiler/rustc_incremental/messages.ftl

@@ -99,6 +99,4 @@ incremental_unrecognized_depnode = unrecognized `DepNode` variant: {$name}
 
 incremental_unrecognized_depnode_label = dep-node label `{$label}` not recognized
 
-incremental_write_dep_graph = failed to write dependency graph to `{$path}`: {$err}
-
 incremental_write_new = failed to write {$name} to `{$path}`: {$err}

compiler/rustc_incremental/src/errors.rs

@@ -272,13 +272,6 @@ pub struct LoadDepGraph {
     pub err: std::io::Error,
 }
 
-#[derive(Diagnostic)]
-#[diag(incremental_write_dep_graph)]
-pub struct WriteDepGraph<'a> {
-    pub path: &'a Path,
-    pub err: std::io::Error,
-}
-
 #[derive(Diagnostic)]
 #[diag(incremental_move_dep_graph)]
 pub struct MoveDepGraph<'a> {

compiler/rustc_middle/src/ty/layout.rs

@@ -1104,7 +1104,7 @@ where
     }
 
     fn is_never(this: TyAndLayout<'tcx>) -> bool {
-        this.ty.kind() == &ty::Never
+        matches!(this.ty.kind(), ty::Never)
     }
 
     fn is_tuple(this: TyAndLayout<'tcx>) -> bool {

compiler/rustc_middle/src/ty/util.rs

@@ -296,7 +296,7 @@ impl<'tcx> TyCtxt<'tcx> {
     ) -> (Ty<'tcx>, Ty<'tcx>) {
         let (mut a, mut b) = (source, target);
         loop {
-            match (&a.kind(), &b.kind()) {
+            match (a.kind(), b.kind()) {
                 (&ty::Adt(a_def, a_args), &ty::Adt(b_def, b_args))
                     if a_def == b_def && a_def.is_struct() =>
                 {

compiler/rustc_mir_build/src/build/expr/as_constant.rs

@@ -127,7 +127,7 @@ fn lit_to_mir_constant<'tcx>(
         Ok(ConstValue::Scalar(Scalar::from_uint(result, width)))
     };
 
-    let value = match (lit, &ty.kind()) {
+    let value = match (lit, ty.kind()) {
         (ast::LitKind::Str(s, _), ty::Ref(_, inner_ty, _)) if inner_ty.is_str() => {
             let s = s.as_str();
             let allocation = Allocation::from_bytes_byte_aligned_immutable(s.as_bytes());

compiler/rustc_mir_build/src/thir/constant.rs

@@ -29,7 +29,7 @@ pub(crate) fn lit_to_const<'tcx>(
             .unwrap_or_else(|| bug!("expected to create ScalarInt from uint {:?}", result)))
     };
 
-    let valtree = match (lit, &ty.kind()) {
+    let valtree = match (lit, ty.kind()) {
         (ast::LitKind::Str(s, _), ty::Ref(_, inner_ty, _)) if inner_ty.is_str() => {
             let str_bytes = s.as_str().as_bytes();
             ty::ValTree::from_raw_bytes(tcx, str_bytes)

compiler/rustc_monomorphize/src/collector.rs

@@ -1035,9 +1035,9 @@ fn find_vtable_types_for_unsizing<'tcx>(
         }
     };
 
-    match (&source_ty.kind(), &target_ty.kind()) {
+    match (source_ty.kind(), target_ty.kind()) {
         (&ty::Ref(_, a, _), &ty::Ref(_, b, _) | &ty::RawPtr(b, _))
-        | (&ty::RawPtr(a, _), &ty::RawPtr(b, _)) => ptr_vtable(*a, *b),
+        | (&ty::RawPtr(a, _), &ty::RawPtr(b, _)) => ptr_vtable(a, b),
         (&ty::Adt(def_a, _), &ty::Adt(def_b, _)) if def_a.is_box() && def_b.is_box() => {
             ptr_vtable(source_ty.boxed_ty(), target_ty.boxed_ty())
         }

compiler/rustc_passes/messages.ftl

@@ -481,10 +481,6 @@ passes_must_not_suspend =
     `must_not_suspend` attribute should be applied to a struct, enum, union, or trait
     .label = is not a struct, enum, union, or trait
 
-passes_must_use_async =
-    `must_use` attribute on `async` functions applies to the anonymous `Future` returned by the function, not the value within
-    .label = this attribute does nothing, the `Future`s returned by async functions are already `must_use`
-
 passes_must_use_no_effect =
     `#[must_use]` has no effect when applied to {$article} {$target}
 

compiler/rustc_passes/src/check_attr.rs

@@ -952,6 +952,16 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                         bare_fn_ty.decl.inputs.len() == 1
                     } else {
                         false
+                    }
+                    || if let Some(&[hir::GenericArg::Type(ty)]) = i
+                        .of_trait
+                        .as_ref()
+                        .and_then(|trait_ref| trait_ref.path.segments.last())
+                        .map(|last_segment| last_segment.args().args)
+                    {
+                        matches!(&ty.kind, hir::TyKind::Tup([_]))
+                    } else {
+                        false
                     };
                 if !is_valid {
                     self.dcx().emit_err(errors::DocFakeVariadicNotValid { span: meta.span() });

compiler/rustc_passes/src/errors.rs

@@ -371,13 +371,6 @@ pub struct FfiConstInvalidTarget {
     pub attr_span: Span,
 }
 
-#[derive(LintDiagnostic)]
-#[diag(passes_must_use_async)]
-pub struct MustUseAsync {
-    #[label]
-    pub span: Span,
-}
-
 #[derive(LintDiagnostic)]
 #[diag(passes_must_use_no_effect)]
 pub struct MustUseNoEffect {

compiler/rustc_trait_selection/src/error_reporting/infer/suggest.rs

@@ -382,7 +382,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         if !expected_inner.is_fn() || !found_inner.is_fn() {
             return;
         }
-        match (&expected_inner.kind(), &found_inner.kind()) {
+        match (expected_inner.kind(), found_inner.kind()) {
             (ty::FnPtr(sig_tys, hdr), ty::FnDef(did, args)) => {
                 let sig = sig_tys.with(*hdr);
                 let expected_sig = &(self.normalize_fn_sig)(sig);

compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs

@@ -4702,10 +4702,15 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
             if let hir::ExprKind::Block(b, _) = body.value.kind
                 && b.expr.is_none()
             {
+                // The span of '}' in the end of block.
+                let span = self.tcx.sess.source_map().end_point(b.span);
                 sugg_spans.push((
-                    // The span will point to the closing curly brace `}` of the block.
+                    span.shrink_to_lo(),
-                    b.span.shrink_to_hi().with_lo(b.span.hi() - BytePos(1)),
+                    format!(
-                    "\n    Ok(())\n}".to_string(),
+                        "{}{}",
+                        "    Ok(())\n",
+                        self.tcx.sess.source_map().indentation_before(span).unwrap_or_default(),
+                    ),
                 ));
             }
             err.multipart_suggestion_verbose(

compiler/rustc_transmute/src/maybe_transmutable/query_context.rs

@@ -4,7 +4,6 @@ use crate::layout;
 pub(crate) trait QueryContext {
     type Def: layout::Def;
     type Ref: layout::Ref;
-    type Scope: Copy;
 }
 
 #[cfg(test)]
@@ -28,20 +27,17 @@ pub(crate) mod test {
     impl QueryContext for UltraMinimal {
         type Def = Def;
         type Ref = !;
-        type Scope = ();
     }
 }
 
 #[cfg(feature = "rustc")]
 mod rustc {
-    use rustc_middle::ty::{Ty, TyCtxt};
+    use rustc_middle::ty::TyCtxt;
 
     use super::*;
 
     impl<'tcx> super::QueryContext for TyCtxt<'tcx> {
         type Def = layout::rustc::Def<'tcx>;
         type Ref = layout::rustc::Ref<'tcx>;
-
-        type Scope = Ty<'tcx>;
     }
 }

compiler/rustc_type_ir/Cargo.toml

@@ -8,6 +8,7 @@ edition = "2021"
 bitflags = "2.4.1"
 derive-where = "1.2.7"
 indexmap = "2.0.0"
+rustc-hash = "1.1.0"
 rustc_ast_ir = { path = "../rustc_ast_ir", default-features = false }
 rustc_data_structures = { path = "../rustc_data_structures", optional = true }
 rustc_index = { path = "../rustc_index", default-features = false }

compiler/rustc_type_ir/src/data_structures.rs

@@ -1,8 +1,13 @@
+use std::hash::BuildHasherDefault;
+
+use rustc_hash::FxHasher;
+pub use rustc_hash::{FxHashMap as HashMap, FxHashSet as HashSet};
+
+pub type IndexMap<K, V> = indexmap::IndexMap<K, V, BuildHasherDefault<FxHasher>>;
+pub type IndexSet<V> = indexmap::IndexSet<V, BuildHasherDefault<FxHasher>>;
+
 #[cfg(feature = "nightly")]
 mod impl_ {
-    pub use rustc_data_structures::fx::{
-        FxHashMap as HashMap, FxHashSet as HashSet, FxIndexMap as IndexMap, FxIndexSet as IndexSet,
-    };
     pub use rustc_data_structures::sso::{SsoHashMap, SsoHashSet};
     pub use rustc_data_structures::stack::ensure_sufficient_stack;
     pub use rustc_data_structures::sync::Lrc;
@@ -10,11 +15,9 @@ mod impl_ {
 
 #[cfg(not(feature = "nightly"))]
 mod impl_ {
-    pub use std::collections::{HashMap, HashMap as SsoHashMap, HashSet, HashSet as SsoHashSet};
+    pub use std::collections::{HashMap as SsoHashMap, HashSet as SsoHashSet};
     pub use std::sync::Arc as Lrc;
 
-    pub use indexmap::{IndexMap, IndexSet};
-
     #[inline]
     pub fn ensure_sufficient_stack<R>(f: impl FnOnce() -> R) -> R {
         f()

library/alloc/tests/boxed.rs

@@ -59,6 +59,7 @@ fn box_deref_lval() {
     assert_eq!(x.get(), 1000);
 }
 
+#[allow(unused)]
 pub struct ConstAllocator;
 
 unsafe impl Allocator for ConstAllocator {

library/core/src/tuple.rs

@@ -122,23 +122,29 @@ macro_rules! tuple_impls {
             }
         }
 
-        #[stable(feature = "array_tuple_conv", since = "1.71.0")]
+        maybe_tuple_doc! {
-        impl<T> From<[T; ${count($T)}]> for ($(${ignore($T)} T,)+) {
+            $($T)+ @
-            #[inline]
+            #[stable(feature = "array_tuple_conv", since = "1.71.0")]
-            #[allow(non_snake_case)]
+            impl<T> From<[T; ${count($T)}]> for ($(${ignore($T)} T,)+) {
-            fn from(array: [T; ${count($T)}]) -> Self {
+                #[inline]
-                let [$($T,)+] = array;
+                #[allow(non_snake_case)]
-                ($($T,)+)
+                fn from(array: [T; ${count($T)}]) -> Self {
+                    let [$($T,)+] = array;
+                    ($($T,)+)
+                }
             }
         }
 
-        #[stable(feature = "array_tuple_conv", since = "1.71.0")]
+        maybe_tuple_doc! {
-        impl<T> From<($(${ignore($T)} T,)+)> for [T; ${count($T)}] {
+            $($T)+ @
-            #[inline]
+            #[stable(feature = "array_tuple_conv", since = "1.71.0")]
-            #[allow(non_snake_case)]
+            impl<T> From<($(${ignore($T)} T,)+)> for [T; ${count($T)}] {
-            fn from(tuple: ($(${ignore($T)} T,)+)) -> Self {
+                #[inline]
-                let ($($T,)+) = tuple;
+                #[allow(non_snake_case)]
-                [$($T,)+]
+                fn from(tuple: ($(${ignore($T)} T,)+)) -> Self {
+                    let ($($T,)+) = tuple;
+                    [$($T,)+]
+                }
             }
         }
     }
@@ -148,7 +154,7 @@ macro_rules! tuple_impls {
 // Otherwise, it hides the docs entirely.
 macro_rules! maybe_tuple_doc {
     ($a:ident @ #[$meta:meta] $item:item) => {
-        #[doc(fake_variadic)]
+        #[cfg_attr(not(bootstrap), doc(fake_variadic))]
         #[doc = "This trait is implemented for tuples up to twelve items long."]
         #[$meta]
         $item

src/librustdoc/html/format.rs

@@ -1288,56 +1288,90 @@ impl clean::Impl {
                 if self.is_negative_trait_impl() {
                     write!(f, "!")?;
                 }
-                ty.print(cx).fmt(f)?;
+                if self.kind.is_fake_variadic()
+                    && let generics = ty.generics()
+                    && let &[inner_type] = generics.as_ref().map_or(&[][..], |v| &v[..])
+                {
+                    let last = ty.last();
+                    if f.alternate() {
+                        write!(f, "{}<", last)?;
+                        self.print_type(inner_type, f, use_absolute, cx)?;
+                        write!(f, ">")?;
+                    } else {
+                        write!(f, "{}&lt;", anchor(ty.def_id(), last, cx).to_string())?;
+                        self.print_type(inner_type, f, use_absolute, cx)?;
+                        write!(f, "&gt;")?;
+                    }
+                } else {
+                    ty.print(cx).fmt(f)?;
+                }
                 write!(f, " for ")?;
             }
 
-            if let clean::Type::Tuple(types) = &self.for_
+            if let Some(ty) = self.kind.as_blanket_ty() {
-                && let [clean::Type::Generic(name)] = &types[..]
-                && (self.kind.is_fake_variadic() || self.kind.is_auto())
-            {
-                // Hardcoded anchor library/core/src/primitive_docs.rs
-                // Link should match `# Trait implementations`
-                primitive_link_fragment(
-                    f,
-                    PrimitiveType::Tuple,
-                    format_args!("({name}₁, {name}₂, …, {name}ₙ)"),
-                    "#trait-implementations-1",
-                    cx,
-                )?;
-            } else if let clean::BareFunction(bare_fn) = &self.for_
-                && let [clean::Argument { type_: clean::Type::Generic(name), .. }] =
-                    &bare_fn.decl.inputs.values[..]
-                && (self.kind.is_fake_variadic() || self.kind.is_auto())
-            {
-                // Hardcoded anchor library/core/src/primitive_docs.rs
-                // Link should match `# Trait implementations`
-
-                print_higher_ranked_params_with_space(&bare_fn.generic_params, cx).fmt(f)?;
-                bare_fn.safety.print_with_space().fmt(f)?;
-                print_abi_with_space(bare_fn.abi).fmt(f)?;
-                let ellipsis = if bare_fn.decl.c_variadic { ", ..." } else { "" };
-                primitive_link_fragment(
-                    f,
-                    PrimitiveType::Tuple,
-                    format_args!("fn({name}₁, {name}₂, …, {name}ₙ{ellipsis})"),
-                    "#trait-implementations-1",
-                    cx,
-                )?;
-                // Write output.
-                if !bare_fn.decl.output.is_unit() {
-                    write!(f, " -> ")?;
-                    fmt_type(&bare_fn.decl.output, f, use_absolute, cx)?;
-                }
-            } else if let Some(ty) = self.kind.as_blanket_ty() {
                 fmt_type(ty, f, use_absolute, cx)?;
             } else {
-                fmt_type(&self.for_, f, use_absolute, cx)?;
+                self.print_type(&self.for_, f, use_absolute, cx)?;
             }
 
             print_where_clause(&self.generics, cx, 0, Ending::Newline).fmt(f)
         })
     }
+    fn print_type<'a, 'tcx: 'a>(
+        &self,
+        type_: &clean::Type,
+        f: &mut fmt::Formatter<'_>,
+        use_absolute: bool,
+        cx: &'a Context<'tcx>,
+    ) -> Result<(), fmt::Error> {
+        if let clean::Type::Tuple(types) = type_
+            && let [clean::Type::Generic(name)] = &types[..]
+            && (self.kind.is_fake_variadic() || self.kind.is_auto())
+        {
+            // Hardcoded anchor library/core/src/primitive_docs.rs
+            // Link should match `# Trait implementations`
+            primitive_link_fragment(
+                f,
+                PrimitiveType::Tuple,
+                format_args!("({name}₁, {name}₂, …, {name}ₙ)"),
+                "#trait-implementations-1",
+                cx,
+            )?;
+        } else if let clean::Type::Array(ty, len) = type_
+            && let clean::Type::Generic(name) = &**ty
+            && &len[..] == "1"
+            && (self.kind.is_fake_variadic() || self.kind.is_auto())
+        {
+            primitive_link(f, PrimitiveType::Array, format_args!("[{name}; N]"), cx)?;
+        } else if let clean::BareFunction(bare_fn) = &type_
+            && let [clean::Argument { type_: clean::Type::Generic(name), .. }] =
+                &bare_fn.decl.inputs.values[..]
+            && (self.kind.is_fake_variadic() || self.kind.is_auto())
+        {
+            // Hardcoded anchor library/core/src/primitive_docs.rs
+            // Link should match `# Trait implementations`
+
+            print_higher_ranked_params_with_space(&bare_fn.generic_params, cx).fmt(f)?;
+            bare_fn.safety.print_with_space().fmt(f)?;
+            print_abi_with_space(bare_fn.abi).fmt(f)?;
+            let ellipsis = if bare_fn.decl.c_variadic { ", ..." } else { "" };
+            primitive_link_fragment(
+                f,
+                PrimitiveType::Tuple,
+                format_args!("fn({name}₁, {name}₂, …, {name}ₙ{ellipsis})"),
+                "#trait-implementations-1",
+                cx,
+            )?;
+            // Write output.
+            if !bare_fn.decl.output.is_unit() {
+                write!(f, " -> ")?;
+                fmt_type(&bare_fn.decl.output, f, use_absolute, cx)?;
+            }
+        } else {
+            fmt_type(&type_, f, use_absolute, cx)?;
+        }
+        Ok(())
+    }
 }
 
 impl clean::Arguments {

tests/rustdoc/primitive-tuple-variadic.rs

@@ -16,3 +16,20 @@ pub trait Bar {}
 //@ has - '//section[@id="impl-Bar-for-(U,)"]/h3' 'impl<U: Foo> Bar for (U₁, U₂, …, Uₙ)'
 #[doc(fake_variadic)]
 impl<U: Foo> Bar for (U,) {}
+
+pub trait Baz<T> { fn baz(&self) -> T { todo!() } }
+
+//@ has foo/trait.Baz.html
+//@ has - '//section[@id="impl-Baz%3C(T,)%3E-for-%5BT;+1%5D"]/h3' 'impl<T> Baz<(T₁, T₂, …, Tₙ)> for [T; N]'
+#[doc(fake_variadic)]
+impl<T> Baz<(T,)> for [T; 1] {}
+
+//@ has foo/trait.Baz.html
+//@ has - '//section[@id="impl-Baz%3C%5BT;+1%5D%3E-for-(T,)"]/h3' 'impl<T> Baz<[T; N]> for (T₁, T₂, …, Tₙ)'
+#[doc(fake_variadic)]
+impl<T> Baz<[T; 1]> for (T,) {}
+
+//@ has foo/trait.Baz.html
+//@ has - '//section[@id="impl-Baz%3CT%3E-for-(T,)"]/h3' 'impl<T> Baz<T> for (T₁, T₂, …, Tₙ)'
+#[doc(fake_variadic)]
+impl<T> Baz<T> for (T,) {}

tests/ui/coercion/cast-higher-ranked-unsafe-fn-ptr.rs

@@ -0,0 +1,14 @@
+//@ check-pass
+
+fn higher_ranked_fndef(ctx: &mut ()) {}
+
+fn test(higher_ranked_fnptr: fn(&mut ())) {
+    fn as_unsafe<T>(_: unsafe fn(T)) {}
+
+    // Make sure that we can cast higher-ranked fn items and pointers to
+    // a non-higher-ranked target.
+    as_unsafe(higher_ranked_fndef);
+    as_unsafe(higher_ranked_fnptr);
+}
+
+fn main() {}

tests/ui/consts/min_const_fn/allow_const_fn_ptr_run_pass.rs

@@ -1,6 +1,4 @@
 //@ run-pass
-#![feature(rustc_allow_const_fn_unstable)]
-
 #![feature(rustc_attrs, staged_api)]
 #![stable(feature = "rust1", since = "1.0.0")]
 

tests/ui/consts/min_const_fn/min_const_fn_libstd_stability.rs

@@ -28,9 +28,11 @@ const fn bar2() -> u32 { foo2() } //~ ERROR not yet stable as a const fn
 // conformity is required
 const fn bar3() -> u32 {
     let x = std::cell::Cell::new(0u32);
-    x.get()
+    x.get();
     //~^ ERROR const-stable function cannot use `#[feature(const_refs_to_cell)]`
     //~| ERROR cannot call non-const fn
+    foo()
+    //~^ ERROR is not yet stable as a const fn
 }
 
 // check whether this function cannot be called even with the feature gate active

tests/ui/consts/min_const_fn/min_const_fn_libstd_stability.stderr

@@ -17,7 +17,7 @@ LL | const fn bar2() -> u32 { foo2() }
 error: const-stable function cannot use `#[feature(const_refs_to_cell)]`
   --> $DIR/min_const_fn_libstd_stability.rs:31:5
    |
-LL |     x.get()
+LL |     x.get();
    |     ^
    |
 help: if it is not part of the public API, make this function unstably const
@@ -25,7 +25,7 @@ help: if it is not part of the public API, make this function unstably const
 LL + #[rustc_const_unstable(feature = "...", issue = "...")]
 LL | const fn bar3() -> u32 {
    |
-help: otherwise `#[rustc_allow_const_fn_unstable]` can be used to bypass stability checks
+help: otherwise `#[rustc_allow_const_fn_unstable]` can be used to bypass stability checks (but requires team approval)
    |
 LL + #[rustc_allow_const_fn_unstable(const_refs_to_cell)]
 LL | const fn bar3() -> u32 {
@@ -34,19 +34,27 @@ LL | const fn bar3() -> u32 {
 error[E0015]: cannot call non-const fn `Cell::<u32>::get` in constant functions
   --> $DIR/min_const_fn_libstd_stability.rs:31:7
    |
-LL |     x.get()
+LL |     x.get();
    |       ^^^^^
    |
    = note: calls in constant functions are limited to constant functions, tuple structs and tuple variants
 
+error: `foo` is not yet stable as a const fn
+  --> $DIR/min_const_fn_libstd_stability.rs:34:5
+   |
+LL |     foo()
+   |     ^^^^^
+   |
+   = help: const-stable functions can only call other const-stable functions
+
 error: `foo2_gated` is not yet stable as a const fn
-  --> $DIR/min_const_fn_libstd_stability.rs:43:32
+  --> $DIR/min_const_fn_libstd_stability.rs:45:32
    |
 LL | const fn bar2_gated() -> u32 { foo2_gated() }
    |                                ^^^^^^^^^^^^
    |
    = help: const-stable functions can only call other const-stable functions
 
-error: aborting due to 5 previous errors
+error: aborting due to 6 previous errors
 
 For more information about this error, try `rustc --explain E0015`.

tests/ui/dyn-keyword/suggest-dyn-on-bare-trait-in-pat.rs

@@ -0,0 +1,14 @@
+//@ edition: 2021
+
+trait Trait {}
+
+impl dyn Trait {
+    const CONST: () = ();
+}
+
+fn main() {
+    match () {
+        Trait::CONST => {}
+        //~^ ERROR trait objects must include the `dyn` keyword
+    }
+}

tests/ui/dyn-keyword/suggest-dyn-on-bare-trait-in-pat.stderr

@@ -0,0 +1,14 @@
+error[E0782]: trait objects must include the `dyn` keyword
+  --> $DIR/suggest-dyn-on-bare-trait-in-pat.rs:11:9
+   |
+LL |         Trait::CONST => {}
+   |         ^^^^^
+   |
+help: add `dyn` keyword before this trait
+   |
+LL |         <dyn Trait>::CONST => {}
+   |         ++++      +
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0782`.

tests/ui/return/return-from-residual-sugg-issue-125997.fixed

@@ -9,7 +9,6 @@ use std::io::prelude::*;
 fn test1() -> Result<(), Box<dyn std::error::Error>> {
     let mut _file = File::create("foo.txt")?;
     //~^ ERROR the `?` operator can only be used in a function
-
     Ok(())
 }
 
@@ -17,7 +16,6 @@ fn test2() -> Result<(), Box<dyn std::error::Error>> {
     let mut _file = File::create("foo.txt")?;
     //~^ ERROR the `?` operator can only be used in a function
     println!();
-
     Ok(())
 }
 
@@ -27,9 +25,8 @@ macro_rules! mac {
             let mut _file = File::create("foo.txt")?;
             //~^ ERROR the `?` operator can only be used in a function
             println!();
-        
+            Ok(())
-    Ok(())
+        }
-}
     };
 }
 
@@ -39,23 +36,20 @@ impl A {
     fn test4(&self) -> Result<(), Box<dyn std::error::Error>> {
         let mut _file = File::create("foo.txt")?;
         //~^ ERROR the `?` operator can only be used in a method
-    
+        Ok(())
-    Ok(())
+    }
-}
 
     fn test5(&self) -> Result<(), Box<dyn std::error::Error>> {
         let mut _file = File::create("foo.txt")?;
         //~^ ERROR the `?` operator can only be used in a method
         println!();
-    
+        Ok(())
-    Ok(())
+    }
-}
 }
 
 fn main() -> Result<(), Box<dyn std::error::Error>> {
     let mut _file = File::create("foo.txt")?;
     //~^ ERROR the `?` operator can only be used in a function
     mac!();
-
     Ok(())
 }

tests/ui/return/return-from-residual-sugg-issue-125997.stderr

@@ -12,9 +12,7 @@ help: consider adding return type
 LL ~ fn test1() -> Result<(), Box<dyn std::error::Error>> {
 LL |     let mut _file = File::create("foo.txt")?;
 LL |
-LL + 
 LL +     Ok(())
-LL + }
    |
 
 error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`)
@@ -32,9 +30,7 @@ LL ~ fn test2() -> Result<(), Box<dyn std::error::Error>> {
 LL |     let mut _file = File::create("foo.txt")?;
 LL |
 LL |     println!();
-LL + 
 LL +     Ok(())
-LL + }
    |
 
 error[E0277]: the `?` operator can only be used in a method that returns `Result` or `Option` (or another type that implements `FromResidual`)
@@ -51,9 +47,8 @@ help: consider adding return type
 LL ~     fn test4(&self) -> Result<(), Box<dyn std::error::Error>> {
 LL |         let mut _file = File::create("foo.txt")?;
 LL |
-LL ~     
+LL ~         Ok(())
-LL +     Ok(())
+LL ~     }
-LL + }
    |
 
 error[E0277]: the `?` operator can only be used in a method that returns `Result` or `Option` (or another type that implements `FromResidual`)
@@ -71,9 +66,8 @@ LL ~     fn test5(&self) -> Result<(), Box<dyn std::error::Error>> {
 LL |         let mut _file = File::create("foo.txt")?;
 LL |
 LL |         println!();
-LL ~     
+LL ~         Ok(())
-LL +     Ok(())
+LL ~     }
-LL + }
    |
 
 error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`)
@@ -91,9 +85,7 @@ LL ~ fn main() -> Result<(), Box<dyn std::error::Error>> {
 LL |     let mut _file = File::create("foo.txt")?;
 LL |
 LL |     mac!();
-LL + 
 LL +     Ok(())
-LL + }
    |
 
 error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`)
@@ -115,9 +107,8 @@ LL ~         fn test3() -> Result<(), Box<dyn std::error::Error>> {
 LL |             let mut _file = File::create("foo.txt")?;
 LL |
 LL |             println!();
-LL ~         
+LL ~             Ok(())
-LL +     Ok(())
+LL ~         }
-LL + }
    |
 
 error: aborting due to 6 previous errors

tests/ui/try-trait/try-operator-on-main.stderr

@@ -14,9 +14,7 @@ LL ~ fn main() -> Result<(), Box<dyn std::error::Error>> {
 LL |     // error for a `Try` type on a non-`Try` fn
 ...
 LL |     try_trait_generic::<()>();
-LL + 
 LL +     Ok(())
-LL + }
    |
 
 error[E0277]: the `?` operator can only be applied to values that implement `Try`