Merge from rustc

16 files changed, 92 insertions, 86 deletions

diff --git a/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs b/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs
index 8ccb2a8483a..5193333be8e 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs
@@ -1087,9 +1087,9 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                 values
             }
 
-            (ty::FnDef(did1, args1), ty::FnPtr(sig2)) => {
+            (ty::FnDef(did1, args1), ty::FnPtr(sig_tys2, hdr2)) => {
                 let sig1 = self.tcx.fn_sig(*did1).instantiate(self.tcx, args1);
-                let mut values = self.cmp_fn_sig(&sig1, sig2);
+                let mut values = self.cmp_fn_sig(&sig1, &sig_tys2.with(*hdr2));
                 values.0.push_highlighted(format!(
                     " {{{}}}",
                     self.tcx.def_path_str_with_args(*did1, args1)
@@ -1097,16 +1097,18 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                 values
             }
 
-            (ty::FnPtr(sig1), ty::FnDef(did2, args2)) => {
+            (ty::FnPtr(sig_tys1, hdr1), ty::FnDef(did2, args2)) => {
                 let sig2 = self.tcx.fn_sig(*did2).instantiate(self.tcx, args2);
-                let mut values = self.cmp_fn_sig(sig1, &sig2);
+                let mut values = self.cmp_fn_sig(&sig_tys1.with(*hdr1), &sig2);
                 values
                     .1
                     .push_normal(format!(" {{{}}}", self.tcx.def_path_str_with_args(*did2, args2)));
                 values
             }
 
-            (ty::FnPtr(sig1), ty::FnPtr(sig2)) => self.cmp_fn_sig(sig1, sig2),
+            (ty::FnPtr(sig_tys1, hdr1), ty::FnPtr(sig_tys2, hdr2)) => {
+                self.cmp_fn_sig(&sig_tys1.with(*hdr1), &sig_tys2.with(*hdr2))
+            }
 
             _ => {
                 let mut strs = (DiagStyledString::new(), DiagStyledString::new());
diff --git a/compiler/rustc_trait_selection/src/error_reporting/infer/note_and_explain.rs b/compiler/rustc_trait_selection/src/error_reporting/infer/note_and_explain.rs
index 864510bb650..05c79170902 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/infer/note_and_explain.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/infer/note_and_explain.rs
@@ -4,6 +4,7 @@ use rustc_hir as hir;
 use rustc_hir::def::DefKind;
 use rustc_middle::traits::{ObligationCause, ObligationCauseCode};
 use rustc_middle::ty::error::{ExpectedFound, TypeError};
+use rustc_middle::ty::fast_reject::{DeepRejectCtxt, TreatParams};
 use rustc_middle::ty::print::{FmtPrinter, Printer};
 use rustc_middle::ty::{self, suggest_constraining_type_param, Ty};
 use rustc_span::def_id::DefId;
@@ -313,11 +314,15 @@ impl<T> Trait<T> for X {
                     (ty::Dynamic(t, _, ty::DynKind::Dyn), _)
                         if let Some(def_id) = t.principal_def_id() =>
                     {
-                        let mut impl_def_ids = vec![];
+                        let mut has_matching_impl = false;
                         tcx.for_each_relevant_impl(def_id, values.found, |did| {
-                            impl_def_ids.push(did)
+                            if DeepRejectCtxt::new(tcx, TreatParams::ForLookup)
+                                .types_may_unify(values.found, tcx.type_of(did).skip_binder())
+                            {
+                                has_matching_impl = true;
+                            }
                         });
-                        if let [_] = &impl_def_ids[..] {
+                        if has_matching_impl {
                             let trait_name = tcx.item_name(def_id);
                             diag.help(format!(
                                 "`{}` implements `{trait_name}` so you could box the found value \
@@ -330,11 +335,15 @@ impl<T> Trait<T> for X {
                     (_, ty::Dynamic(t, _, ty::DynKind::Dyn))
                         if let Some(def_id) = t.principal_def_id() =>
                     {
-                        let mut impl_def_ids = vec![];
+                        let mut has_matching_impl = false;
                         tcx.for_each_relevant_impl(def_id, values.expected, |did| {
-                            impl_def_ids.push(did)
+                            if DeepRejectCtxt::new(tcx, TreatParams::ForLookup)
+                                .types_may_unify(values.expected, tcx.type_of(did).skip_binder())
+                            {
+                                has_matching_impl = true;
+                            }
                         });
-                        if let [_] = &impl_def_ids[..] {
+                        if has_matching_impl {
                             let trait_name = tcx.item_name(def_id);
                             diag.help(format!(
                                 "`{}` implements `{trait_name}` so you could change the expected \
@@ -346,11 +355,15 @@ impl<T> Trait<T> for X {
                     (ty::Dynamic(t, _, ty::DynKind::DynStar), _)
                         if let Some(def_id) = t.principal_def_id() =>
                     {
-                        let mut impl_def_ids = vec![];
+                        let mut has_matching_impl = false;
                         tcx.for_each_relevant_impl(def_id, values.found, |did| {
-                            impl_def_ids.push(did)
+                            if DeepRejectCtxt::new(tcx, TreatParams::ForLookup)
+                                .types_may_unify(values.found, tcx.type_of(did).skip_binder())
+                            {
+                                has_matching_impl = true;
+                            }
                         });
-                        if let [_] = &impl_def_ids[..] {
+                        if has_matching_impl {
                             let trait_name = tcx.item_name(def_id);
                             diag.help(format!(
                                 "`{}` implements `{trait_name}`, `#[feature(dyn_star)]` is likely \
@@ -441,9 +454,9 @@ impl<T> Trait<T> for X {
                             }
                         }
                     }
-                    (ty::FnPtr(sig), ty::FnDef(def_id, _))
-                    | (ty::FnDef(def_id, _), ty::FnPtr(sig)) => {
-                        if tcx.fn_sig(def_id).skip_binder().safety() < sig.safety() {
+                    (ty::FnPtr(_, hdr), ty::FnDef(def_id, _))
+                    | (ty::FnDef(def_id, _), ty::FnPtr(_, hdr)) => {
+                        if tcx.fn_sig(def_id).skip_binder().safety() < hdr.safety {
                             diag.note(
                                 "unsafe functions cannot be coerced into safe function pointers",
                             );
diff --git a/compiler/rustc_trait_selection/src/error_reporting/infer/suggest.rs b/compiler/rustc_trait_selection/src/error_reporting/infer/suggest.rs
index ee159aa0b77..35f68a56d2d 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/infer/suggest.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/infer/suggest.rs
@@ -383,8 +383,9 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
             return;
         }
         match (&expected_inner.kind(), &found_inner.kind()) {
-            (ty::FnPtr(sig), ty::FnDef(did, args)) => {
-                let expected_sig = &(self.normalize_fn_sig)(*sig);
+            (ty::FnPtr(sig_tys, hdr), ty::FnDef(did, args)) => {
+                let sig = sig_tys.with(*hdr);
+                let expected_sig = &(self.normalize_fn_sig)(sig);
                 let found_sig =
                     &(self.normalize_fn_sig)(self.tcx.fn_sig(*did).instantiate(self.tcx, args));
 
@@ -402,11 +403,11 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                     (false, true) => FunctionPointerSuggestion::RemoveRef { span, fn_name },
                     (true, true) => {
                         diag.subdiagnostic(FnItemsAreDistinct);
-                        FunctionPointerSuggestion::CastRef { span, fn_name, sig: *sig }
+                        FunctionPointerSuggestion::CastRef { span, fn_name, sig }
                     }
                     (false, false) => {
                         diag.subdiagnostic(FnItemsAreDistinct);
-                        FunctionPointerSuggestion::Cast { span, fn_name, sig: *sig }
+                        FunctionPointerSuggestion::Cast { span, fn_name, sig }
                     }
                 };
                 diag.subdiagnostic(sugg);
@@ -449,10 +450,10 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
 
                 diag.subdiagnostic(sug);
             }
-            (ty::FnDef(did, args), ty::FnPtr(sig)) => {
+            (ty::FnDef(did, args), ty::FnPtr(sig_tys, hdr)) => {
                 let expected_sig =
                     &(self.normalize_fn_sig)(self.tcx.fn_sig(*did).instantiate(self.tcx, args));
-                let found_sig = &(self.normalize_fn_sig)(*sig);
+                let found_sig = &(self.normalize_fn_sig)(sig_tys.with(*hdr));
 
                 if !self.same_type_modulo_infer(*found_sig, *expected_sig) {
                     return;
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
index 95d4509c100..326a0e4e35c 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
@@ -230,8 +230,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                             post_message,
                         );
 
-                        let (err_msg, safe_transmute_explanation) = if Some(main_trait_ref.def_id())
-                            == self.tcx.lang_items().transmute_trait()
+                        let (err_msg, safe_transmute_explanation) = if self.tcx.is_lang_item(main_trait_ref.def_id(), LangItem::TransmuteTrait)
                         {
                             // Recompute the safe transmute reason and use that for the error reporting
                             match self.get_safe_transmute_error_and_reason(
@@ -375,7 +374,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                         let impl_candidates = self.find_similar_impl_candidates(leaf_trait_predicate);
                         suggested = if let &[cand] = &impl_candidates[..] {
                             let cand = cand.trait_ref;
-                            if let (ty::FnPtr(_), ty::FnDef(..)) =
+                            if let (ty::FnPtr(..), ty::FnDef(..)) =
                                 (cand.self_ty().kind(), main_trait_ref.self_ty().skip_binder().kind())
                             {
                                 err.span_suggestion(
@@ -687,10 +686,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         let mut applied_do_not_recommend = false;
         loop {
             if let ObligationCauseCode::ImplDerived(ref c) = base_cause {
-                if self.tcx.has_attrs_with_path(
-                    c.impl_or_alias_def_id,
-                    &[sym::diagnostic, sym::do_not_recommend],
-                ) {
+                if self.tcx.do_not_recommend_impl(c.impl_or_alias_def_id) {
                     let code = (*c.derived.parent_code).clone();
                     obligation.cause.map_code(|_| code);
                     obligation.predicate = c.derived.parent_trait_pred.upcast(self.tcx);
@@ -793,8 +789,8 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
             // is unimplemented is because async closures don't implement `Fn`/`FnMut`
             // if they have captures.
             if let Some(by_ref_captures) = by_ref_captures
-                && let ty::FnPtr(sig) = by_ref_captures.kind()
-                && !sig.skip_binder().output().is_unit()
+                && let ty::FnPtr(sig_tys, _) = by_ref_captures.kind()
+                && !sig_tys.skip_binder().output().is_unit()
             {
                 let mut err = self.dcx().create_err(AsyncClosureNotFn {
                     span: self.tcx.def_span(closure_def_id),
@@ -1060,7 +1056,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                     "`{ty}` is forbidden as the type of a const generic parameter",
                 )
             }
-            ty::FnPtr(_) => {
+            ty::FnPtr(..) => {
                 struct_span_code_err!(
                     self.dcx(),
                     span,
@@ -1629,11 +1625,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                 .tcx
                 .all_impls(def_id)
                 // ignore `do_not_recommend` items
-                .filter(|def_id| {
-                    !self
-                        .tcx
-                        .has_attrs_with_path(*def_id, &[sym::diagnostic, sym::do_not_recommend])
-                })
+                .filter(|def_id| !self.tcx.do_not_recommend_impl(*def_id))
                 // Ignore automatically derived impls and `!Trait` impls.
                 .filter_map(|def_id| self.tcx.impl_trait_header(def_id))
                 .filter_map(|header| {
@@ -1843,10 +1835,10 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
             if let &[cand] = &candidates[..] {
                 let (desc, mention_castable) =
                     match (cand.self_ty().kind(), trait_ref.self_ty().skip_binder().kind()) {
-                        (ty::FnPtr(_), ty::FnDef(..)) => {
+                        (ty::FnPtr(..), ty::FnDef(..)) => {
                             (" implemented for fn pointer `", ", cast using `as`")
                         }
-                        (ty::FnPtr(_), _) => (" implemented for fn pointer `", ""),
+                        (ty::FnPtr(..), _) => (" implemented for fn pointer `", ""),
                         _ => (" implemented for `", ""),
                     };
                 err.highlighted_help(vec![
@@ -1903,12 +1895,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         let impl_candidates = impl_candidates
             .into_iter()
             .cloned()
-            .filter(|cand| {
-                !self.tcx.has_attrs_with_path(
-                    cand.impl_def_id,
-                    &[sym::diagnostic, sym::do_not_recommend],
-                )
-            })
+            .filter(|cand| !self.tcx.do_not_recommend_impl(cand.impl_def_id))
             .collect::<Vec<_>>();
 
         let def_id = trait_ref.def_id();
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs
index 9269177eb50..d0f76f0d50e 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs
@@ -1077,10 +1077,10 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         let Some((def_id_or_name, output, inputs)) =
             (self.autoderef_steps)(found).into_iter().find_map(|(found, _)| {
                 match *found.kind() {
-                    ty::FnPtr(fn_sig) => Some((
+                    ty::FnPtr(sig_tys, _) => Some((
                         DefIdOrName::Name("function pointer"),
-                        fn_sig.output(),
-                        fn_sig.inputs(),
+                        sig_tys.output(),
+                        sig_tys.inputs(),
                     )),
                     ty::FnDef(def_id, _) => {
                         let fn_sig = found.fn_sig(self.tcx);
@@ -1977,20 +1977,22 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         let ObligationCauseCode::FunctionArg { arg_hir_id, .. } = cause else {
             return;
         };
-        let ty::FnPtr(expected) = expected.kind() else {
+        let ty::FnPtr(sig_tys, hdr) = expected.kind() else {
             return;
         };
-        let ty::FnPtr(found) = found.kind() else {
+        let expected = sig_tys.with(*hdr);
+        let ty::FnPtr(sig_tys, hdr) = found.kind() else {
             return;
         };
+        let found = sig_tys.with(*hdr);
         let Node::Expr(arg) = self.tcx.hir_node(*arg_hir_id) else {
             return;
         };
         let hir::ExprKind::Path(path) = arg.kind else {
             return;
         };
-        let expected_inputs = self.tcx.instantiate_bound_regions_with_erased(*expected).inputs();
-        let found_inputs = self.tcx.instantiate_bound_regions_with_erased(*found).inputs();
+        let expected_inputs = self.tcx.instantiate_bound_regions_with_erased(expected).inputs();
+        let found_inputs = self.tcx.instantiate_bound_regions_with_erased(found).inputs();
         let both_tys = expected_inputs.iter().copied().zip(found_inputs.iter().copied());
 
         let arg_expr = |infcx: &InferCtxt<'tcx>, name, expected: Ty<'tcx>, found: Ty<'tcx>| {
@@ -2829,7 +2831,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                                     // Do not suggest relaxing if there is an explicit `Sized` obligation.
                                     && !bounds.iter()
                                         .filter_map(|bound| bound.trait_ref())
-                                        .any(|tr| tr.trait_def_id() == tcx.lang_items().sized_trait())
+                                        .any(|tr| tr.trait_def_id().is_some_and(|def_id| tcx.is_lang_item(def_id, LangItem::Sized)))
                                 {
                                     let (span, separator) = if let [.., last] = bounds {
                                         (last.span().shrink_to_hi(), " +")
@@ -4790,13 +4792,13 @@ fn hint_missing_borrow<'tcx>(
     }
 
     let found_args = match found.kind() {
-        ty::FnPtr(f) => infcx.enter_forall(*f, |f| f.inputs().iter()),
+        ty::FnPtr(sig_tys, _) => infcx.enter_forall(*sig_tys, |sig_tys| sig_tys.inputs().iter()),
         kind => {
             span_bug!(span, "found was converted to a FnPtr above but is now {:?}", kind)
         }
     };
     let expected_args = match expected.kind() {
-        ty::FnPtr(f) => infcx.enter_forall(*f, |f| f.inputs().iter()),
+        ty::FnPtr(sig_tys, _) => infcx.enter_forall(*sig_tys, |sig_tys| sig_tys.inputs().iter()),
         kind => {
             span_bug!(span, "expected was converted to a FnPtr above but is now {:?}", kind)
         }
diff --git a/compiler/rustc_trait_selection/src/solve/fulfill.rs b/compiler/rustc_trait_selection/src/solve/fulfill.rs
index 49fa775a0a1..de8951ef720 100644
--- a/compiler/rustc_trait_selection/src/solve/fulfill.rs
+++ b/compiler/rustc_trait_selection/src/solve/fulfill.rs
@@ -13,7 +13,6 @@ use rustc_middle::bug;
 use rustc_middle::ty::error::{ExpectedFound, TypeError};
 use rustc_middle::ty::{self, TyCtxt};
 use rustc_next_trait_solver::solve::{GenerateProofTree, SolverDelegateEvalExt as _};
-use rustc_span::symbol::sym;
 
 use super::delegate::SolverDelegate;
 use super::inspect::{self, ProofTreeInferCtxtExt, ProofTreeVisitor};
@@ -440,10 +439,7 @@ impl<'tcx> ProofTreeVisitor<'tcx> for BestObligation<'tcx> {
             source: CandidateSource::Impl(impl_def_id),
             result: _,
         } = candidate.kind()
-            && goal
-                .infcx()
-                .tcx
-                .has_attrs_with_path(impl_def_id, &[sym::diagnostic, sym::do_not_recommend])
+            && goal.infcx().tcx.do_not_recommend_impl(impl_def_id)
         {
             return ControlFlow::Break(self.obligation.clone());
         }
diff --git a/compiler/rustc_trait_selection/src/solve/inspect/analyse.rs b/compiler/rustc_trait_selection/src/solve/inspect/analyse.rs
index 4e4022830d4..51dda25d8ad 100644
--- a/compiler/rustc_trait_selection/src/solve/inspect/analyse.rs
+++ b/compiler/rustc_trait_selection/src/solve/inspect/analyse.rs
@@ -9,6 +9,8 @@
 //! coherence right now and was annoying to implement, so I am leaving it
 //! as is until we start using it for something else.
 
+use std::assert_matches::assert_matches;
+
 use rustc_ast_ir::try_visit;
 use rustc_ast_ir::visit::VisitorResult;
 use rustc_infer::infer::{DefineOpaqueTypes, InferCtxt, InferOk};
@@ -273,10 +275,10 @@ impl<'a, 'tcx> InspectGoal<'a, 'tcx> {
                     steps.push(step)
                 }
                 inspect::ProbeStep::MakeCanonicalResponse { shallow_certainty: c } => {
-                    assert!(matches!(
+                    assert_matches!(
                         shallow_certainty.replace(c),
                         None | Some(Certainty::Maybe(MaybeCause::Ambiguity))
-                    ));
+                    );
                 }
                 inspect::ProbeStep::NestedProbe(ref probe) => {
                     match probe.kind {
diff --git a/compiler/rustc_trait_selection/src/solve/normalize.rs b/compiler/rustc_trait_selection/src/solve/normalize.rs
index 419d7e704de..c93c40b4826 100644
--- a/compiler/rustc_trait_selection/src/solve/normalize.rs
+++ b/compiler/rustc_trait_selection/src/solve/normalize.rs
@@ -1,3 +1,4 @@
+use std::assert_matches::assert_matches;
 use std::fmt::Debug;
 use std::marker::PhantomData;
 
@@ -63,7 +64,7 @@ where
     E: FromSolverError<'tcx, NextSolverError<'tcx>>,
 {
     fn normalize_alias_ty(&mut self, alias_ty: Ty<'tcx>) -> Result<Ty<'tcx>, Vec<E>> {
-        assert!(matches!(alias_ty.kind(), ty::Alias(..)));
+        assert_matches!(alias_ty.kind(), ty::Alias(..));
 
         let infcx = self.at.infcx;
         let tcx = infcx.tcx;
diff --git a/compiler/rustc_trait_selection/src/traits/misc.rs b/compiler/rustc_trait_selection/src/traits/misc.rs
index 9a127e752a6..3e65194577e 100644
--- a/compiler/rustc_trait_selection/src/traits/misc.rs
+++ b/compiler/rustc_trait_selection/src/traits/misc.rs
@@ -1,5 +1,7 @@
 //! Miscellaneous type-system utilities that are too small to deserve their own modules.
 
+use std::assert_matches::assert_matches;
+
 use hir::LangItem;
 use rustc_ast::Mutability;
 use rustc_data_structures::fx::FxIndexSet;
@@ -92,7 +94,7 @@ pub fn type_allowed_to_implement_const_param_ty<'tcx>(
     lang_item: LangItem,
     parent_cause: ObligationCause<'tcx>,
 ) -> Result<(), ConstParamTyImplementationError<'tcx>> {
-    assert!(matches!(lang_item, LangItem::ConstParamTy | LangItem::UnsizedConstParamTy));
+    assert_matches!(lang_item, LangItem::ConstParamTy | LangItem::UnsizedConstParamTy);
 
     let inner_tys: Vec<_> = match *self_type.kind() {
         // Trivially okay as these types are all:
diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs
index 4b62a5c59b2..568214fe022 100644
--- a/compiler/rustc_trait_selection/src/traits/project.rs
+++ b/compiler/rustc_trait_selection/src/traits/project.rs
@@ -1110,7 +1110,7 @@ fn assemble_candidates_from_impls<'cx, 'tcx>(
                         | ty::Error(_) => false,
                     }
                 } else if tcx.is_lang_item(trait_ref.def_id, LangItem::PointeeTrait) {
-                    let tail = selcx.tcx().struct_tail_with_normalize(
+                    let tail = selcx.tcx().struct_tail_raw(
                         self_ty,
                         |ty| {
                             // We throw away any obligations we get from this, since we normalize
@@ -1149,10 +1149,10 @@ fn assemble_candidates_from_impls<'cx, 'tcx>(
                         | ty::Never
                         // Extern types have unit metadata, according to RFC 2850
                         | ty::Foreign(_)
-                        // If returned by `struct_tail_without_normalization` this is a unit struct
+                        // If returned by `struct_tail` this is a unit struct
                         // without any fields, or not a struct, and therefore is Sized.
                         | ty::Adt(..)
-                        // If returned by `struct_tail_without_normalization` this is the empty tuple.
+                        // If returned by `struct_tail` this is the empty tuple.
                         | ty::Tuple(..)
                         // Integers and floats are always Sized, and so have unit type metadata.
                         | ty::Infer(ty::InferTy::IntVar(_) | ty::InferTy::FloatVar(..)) => true,
@@ -1636,7 +1636,7 @@ fn confirm_fn_pointer_candidate<'cx, 'tcx>(
             .generics_of(def_id)
             .host_effect_index
             .map_or(tcx.consts.true_, |idx| args.const_at(idx)),
-        ty::FnPtr(_) => tcx.consts.true_,
+        ty::FnPtr(..) => tcx.consts.true_,
         _ => unreachable!("only expected FnPtr or FnDef in `confirm_fn_pointer_candidate`"),
     };
 
diff --git a/compiler/rustc_trait_selection/src/traits/query/dropck_outlives.rs b/compiler/rustc_trait_selection/src/traits/query/dropck_outlives.rs
index d3a1ed52d2e..7d30e652449 100644
--- a/compiler/rustc_trait_selection/src/traits/query/dropck_outlives.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/dropck_outlives.rs
@@ -33,7 +33,7 @@ pub fn trivial_dropck_outlives<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> bool {
         | ty::Float(_)
         | ty::Never
         | ty::FnDef(..)
-        | ty::FnPtr(_)
+        | ty::FnPtr(..)
         | ty::Char
         | ty::CoroutineWitness(..)
         | ty::RawPtr(_, _)
@@ -224,7 +224,7 @@ pub fn dtorck_constraint_for_ty_inner<'tcx>(
         | ty::RawPtr(..)
         | ty::Ref(..)
         | ty::FnDef(..)
-        | ty::FnPtr(_)
+        | ty::FnPtr(..)
         | ty::CoroutineWitness(..) => {
             // these types never have a destructor
         }
diff --git a/compiler/rustc_trait_selection/src/traits/query/type_op/prove_predicate.rs b/compiler/rustc_trait_selection/src/traits/query/type_op/prove_predicate.rs
index 294c6bfc124..d6687c762c3 100644
--- a/compiler/rustc_trait_selection/src/traits/query/type_op/prove_predicate.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/type_op/prove_predicate.rs
@@ -1,3 +1,4 @@
+use rustc_hir::LangItem;
 use rustc_infer::traits::Obligation;
 pub use rustc_middle::traits::query::type_op::ProvePredicate;
 use rustc_middle::traits::query::NoSolution;
@@ -20,8 +21,7 @@ impl<'tcx> super::QueryTypeOp<'tcx> for ProvePredicate<'tcx> {
         // such cases.
         if let ty::PredicateKind::Clause(ty::ClauseKind::Trait(trait_ref)) =
             key.value.predicate.kind().skip_binder()
-            && let Some(sized_def_id) = tcx.lang_items().sized_trait()
-            && trait_ref.def_id() == sized_def_id
+            && tcx.is_lang_item(trait_ref.def_id(), LangItem::Sized)
             && trait_ref.self_ty().is_trivially_sized(tcx)
         {
             return Some(());
diff --git a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
index 9de62031311..cb8deeaedb6 100644
--- a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
@@ -468,8 +468,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 candidates.vec.push(AsyncClosureCandidate);
             }
             // Provide an impl, but only for suitable `fn` pointers.
-            ty::FnPtr(sig) => {
-                if sig.is_fn_trait_compatible() {
+            ty::FnPtr(sig_tys, hdr) => {
+                if sig_tys.with(hdr).is_fn_trait_compatible() {
                     candidates.vec.push(AsyncClosureCandidate);
                 }
             }
@@ -535,8 +535,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 candidates.ambiguous = true; // Could wind up being a fn() type.
             }
             // Provide an impl, but only for suitable `fn` pointers.
-            ty::FnPtr(sig) => {
-                if sig.is_fn_trait_compatible() {
+            ty::FnPtr(sig_tys, hdr) => {
+                if sig_tys.with(hdr).is_fn_trait_compatible() {
                     candidates
                         .vec
                         .push(FnPointerCandidate { fn_host_effect: self.tcx().consts.true_ });
@@ -819,7 +819,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 | ty::RawPtr(_, _)
                 | ty::Ref(..)
                 | ty::FnDef(..)
-                | ty::FnPtr(_)
+                | ty::FnPtr(..)
                 | ty::Closure(..)
                 | ty::CoroutineClosure(..)
                 | ty::Coroutine(..)
@@ -1207,7 +1207,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             | ty::RawPtr(_, _)
             | ty::Ref(..)
             | ty::FnDef(..)
-            | ty::FnPtr(_)
+            | ty::FnPtr(..)
             | ty::Never
             | ty::Foreign(_)
             | ty::Array(..)
@@ -1290,7 +1290,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             | ty::Ref(_, _, _)
             | ty::FnDef(_, _)
             | ty::Pat(_, _)
-            | ty::FnPtr(_)
+            | ty::FnPtr(..)
             | ty::Dynamic(_, _, _)
             | ty::Closure(..)
             | ty::CoroutineClosure(..)
@@ -1339,7 +1339,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         let self_ty = self.infcx.resolve_vars_if_possible(obligation.self_ty());
 
         match self_ty.skip_binder().kind() {
-            ty::FnPtr(_) => candidates.vec.push(BuiltinCandidate { has_nested: false }),
+            ty::FnPtr(..) => candidates.vec.push(BuiltinCandidate { has_nested: false }),
             ty::Bool
             | ty::Char
             | ty::Int(_)
diff --git a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
index ddd8b970cc8..0d7ceca4301 100644
--- a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
@@ -1398,7 +1398,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 | ty::RawPtr(_, _)
                 | ty::Ref(..)
                 | ty::FnDef(..)
-                | ty::FnPtr(_)
+                | ty::FnPtr(..)
                 | ty::Never
                 | ty::Foreign(_) => {}
 
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
index 1b2767a6a62..f002fa27db2 100644
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -2113,7 +2113,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
             | ty::Bool
             | ty::Float(_)
             | ty::FnDef(..)
-            | ty::FnPtr(_)
+            | ty::FnPtr(..)
             | ty::RawPtr(..)
             | ty::Char
             | ty::Ref(..)
@@ -2170,7 +2170,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
         use self::BuiltinImplConditions::{Ambiguous, None, Where};
 
         match *self_ty.kind() {
-            ty::FnDef(..) | ty::FnPtr(_) | ty::Error(_) => Where(ty::Binder::dummy(Vec::new())),
+            ty::FnDef(..) | ty::FnPtr(..) | ty::Error(_) => Where(ty::Binder::dummy(Vec::new())),
 
             ty::Uint(_)
             | ty::Int(_)
@@ -2332,7 +2332,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
             | ty::Bool
             | ty::Float(_)
             | ty::FnDef(..)
-            | ty::FnPtr(_)
+            | ty::FnPtr(..)
             | ty::Error(_)
             | ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
             | ty::Never
diff --git a/compiler/rustc_trait_selection/src/traits/wf.rs b/compiler/rustc_trait_selection/src/traits/wf.rs
index 7e5fe7e3c94..a3982c3d987 100644
--- a/compiler/rustc_trait_selection/src/traits/wf.rs
+++ b/compiler/rustc_trait_selection/src/traits/wf.rs
@@ -812,7 +812,7 @@ impl<'a, 'tcx> TypeVisitor<TyCtxt<'tcx>> for WfPredicates<'a, 'tcx> {
                 return upvars.visit_with(self);
             }
 
-            ty::FnPtr(_) => {
+            ty::FnPtr(..) => {
                 // Let the visitor iterate into the argument/return
                 // types appearing in the fn signature.
             }