9 files changed, 30 insertions, 24 deletions
diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs
index 6435b05cef8..27284f8b983 100644
--- a/compiler/rustc_hir_analysis/src/astconv/mod.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs
@@ -3140,7 +3140,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
             trait_ref.def_id,
         )?;
 
-        let fn_sig = tcx.bound_fn_sig(assoc.def_id).subst(
+        let fn_sig = tcx.fn_sig(assoc.def_id).subst(
             tcx,
             trait_ref.substs.extend_to(tcx, assoc.def_id, |param, _| tcx.mk_param_from_def(param)),
         );
diff --git a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
index 475be4fde7a..d93d2314ed6 100644
--- a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
+++ b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
@@ -249,7 +249,7 @@ fn compare_method_predicate_entailment<'tcx>(
     let unnormalized_impl_sig = infcx.replace_bound_vars_with_fresh_vars(
         impl_m_span,
         infer::HigherRankedType,
-        tcx.bound_fn_sig(impl_m.def_id).subst_identity(),
+        tcx.fn_sig(impl_m.def_id).subst_identity(),
     );
     let unnormalized_impl_fty = tcx.mk_fn_ptr(ty::Binder::dummy(unnormalized_impl_sig));
 
@@ -257,7 +257,7 @@ fn compare_method_predicate_entailment<'tcx>(
     let impl_sig = ocx.normalize(&norm_cause, param_env, unnormalized_impl_sig);
     debug!("compare_impl_method: impl_fty={:?}", impl_sig);
 
-    let trait_sig = tcx.bound_fn_sig(trait_m.def_id).subst(tcx, trait_to_placeholder_substs);
+    let trait_sig = tcx.fn_sig(trait_m.def_id).subst(tcx, trait_to_placeholder_substs);
     let trait_sig = tcx.liberate_late_bound_regions(impl_m.def_id, trait_sig);
 
     // Next, add all inputs and output as well-formed tys. Importantly,
@@ -422,8 +422,8 @@ fn extract_bad_args_for_implies_lint<'tcx>(
 
     // Map late-bound regions from trait to impl, so the names are right.
     let mapping = std::iter::zip(
-        tcx.bound_fn_sig(trait_m.def_id).subst_identity().bound_vars(),
-        tcx.bound_fn_sig(impl_m.def_id).subst_identity().bound_vars(),
+        tcx.fn_sig(trait_m.def_id).subst_identity().bound_vars(),
+        tcx.fn_sig(impl_m.def_id).subst_identity().bound_vars(),
     )
     .filter_map(|(impl_bv, trait_bv)| {
         if let ty::BoundVariableKind::Region(impl_bv) = impl_bv
@@ -540,7 +540,7 @@ fn compare_asyncness<'tcx>(
     trait_item_span: Option<Span>,
 ) -> Result<(), ErrorGuaranteed> {
     if tcx.asyncness(trait_m.def_id) == hir::IsAsync::Async {
-        match tcx.bound_fn_sig(impl_m.def_id).subst_identity().skip_binder().output().kind() {
+        match tcx.fn_sig(impl_m.def_id).subst_identity().skip_binder().output().kind() {
             ty::Alias(ty::Opaque, ..) => {
                 // allow both `async fn foo()` and `fn foo() -> impl Future`
             }
@@ -643,7 +643,7 @@ pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>(
         infcx.replace_bound_vars_with_fresh_vars(
             return_span,
             infer::HigherRankedType,
-            tcx.bound_fn_sig(impl_m.def_id).subst_identity(),
+            tcx.fn_sig(impl_m.def_id).subst_identity(),
         ),
     );
     impl_sig.error_reported()?;
@@ -657,7 +657,7 @@ pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>(
     let unnormalized_trait_sig = tcx
         .liberate_late_bound_regions(
             impl_m.def_id,
-            tcx.bound_fn_sig(trait_m.def_id).subst(tcx, trait_to_placeholder_substs),
+            tcx.fn_sig(trait_m.def_id).subst(tcx, trait_to_placeholder_substs),
         )
         .fold_with(&mut collector);
     let trait_sig = ocx.normalize(&norm_cause, param_env, unnormalized_trait_sig);
@@ -1117,7 +1117,7 @@ fn compare_self_type<'tcx>(
             ty::ImplContainer => impl_trait_ref.self_ty(),
             ty::TraitContainer => tcx.types.self_param,
         };
-        let self_arg_ty = tcx.bound_fn_sig(method.def_id).subst_identity().input(0);
+        let self_arg_ty = tcx.fn_sig(method.def_id).subst_identity().input(0);
         let param_env = ty::ParamEnv::reveal_all();
 
         let infcx = tcx.infer_ctxt().build();
@@ -1348,8 +1348,8 @@ fn compare_number_of_method_arguments<'tcx>(
     trait_m: &ty::AssocItem,
     trait_item_span: Option<Span>,
 ) -> Result<(), ErrorGuaranteed> {
-    let impl_m_fty = tcx.bound_fn_sig(impl_m.def_id);
-    let trait_m_fty = tcx.bound_fn_sig(trait_m.def_id);
+    let impl_m_fty = tcx.fn_sig(impl_m.def_id);
+    let trait_m_fty = tcx.fn_sig(trait_m.def_id);
     let trait_number_args = trait_m_fty.skip_binder().inputs().skip_binder().len();
     let impl_number_args = impl_m_fty.skip_binder().inputs().skip_binder().len();
 
diff --git a/compiler/rustc_hir_analysis/src/check/intrinsic.rs b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
index fe2720fa1af..955cacf03b1 100644
--- a/compiler/rustc_hir_analysis/src/check/intrinsic.rs
+++ b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
@@ -58,7 +58,12 @@ fn equate_intrinsic_type<'tcx>(
         let fty = tcx.mk_fn_ptr(sig);
         let it_def_id = it.owner_id.def_id;
         let cause = ObligationCause::new(it.span, it_def_id, ObligationCauseCode::IntrinsicType);
-        require_same_types(tcx, &cause, tcx.mk_fn_ptr(tcx.bound_fn_sig(it.owner_id.to_def_id()).subst_identity()), fty);
+        require_same_types(
+            tcx,
+            &cause,
+            tcx.mk_fn_ptr(tcx.fn_sig(it.owner_id).subst_identity()),
+            fty,
+        );
     }
 }
 
diff --git a/compiler/rustc_hir_analysis/src/check/mod.rs b/compiler/rustc_hir_analysis/src/check/mod.rs
index 3b0ddad25fc..2f2ee702837 100644
--- a/compiler/rustc_hir_analysis/src/check/mod.rs
+++ b/compiler/rustc_hir_analysis/src/check/mod.rs
@@ -445,7 +445,7 @@ fn suggestion_signature(assoc: &ty::AssocItem, tcx: TyCtxt<'_>) -> String {
             // regions just fine, showing `fn(&MyType)`.
             fn_sig_suggestion(
                 tcx,
-                tcx.bound_fn_sig(assoc.def_id).subst_identity().skip_binder(),
+                tcx.fn_sig(assoc.def_id).subst_identity().skip_binder(),
                 assoc.ident(tcx),
                 tcx.predicates_of(assoc.def_id),
                 assoc,
diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
index a0a0c72ded9..870c57d5e05 100644
--- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs
+++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
@@ -386,7 +386,7 @@ fn check_gat_where_clauses(tcx: TyCtxt<'_>, associated_items: &[hir::TraitItemRe
                         // `Self::Iter<'a>` is a GAT we want to gather any potential missing bounds from.
                         let sig: ty::FnSig<'_> = tcx.liberate_late_bound_regions(
                             item_def_id.to_def_id(),
-                            tcx.bound_fn_sig(item_def_id.to_def_id()).subst_identity(),
+                            tcx.fn_sig(item_def_id).subst_identity(),
                         );
                         gather_gat_bounds(
                             tcx,
@@ -1018,7 +1018,7 @@ fn check_associated_item(
                 wfcx.register_wf_obligation(span, loc, ty.into());
             }
             ty::AssocKind::Fn => {
-                let sig = tcx.bound_fn_sig(item.def_id).subst_identity();
+                let sig = tcx.fn_sig(item.def_id).subst_identity();
                 let hir_sig = sig_if_method.expect("bad signature for method");
                 check_fn_or_method(
                     wfcx,
@@ -1203,7 +1203,7 @@ fn check_item_fn(
     decl: &hir::FnDecl<'_>,
 ) {
     enter_wf_checking_ctxt(tcx, span, def_id, |wfcx| {
-        let sig = tcx.bound_fn_sig(def_id.into()).subst_identity();
+        let sig = tcx.fn_sig(def_id).subst_identity();
         check_fn_or_method(wfcx, ident.span, sig, decl, def_id);
     })
 }
@@ -1638,7 +1638,7 @@ fn check_method_receiver<'tcx>(
 
     let span = fn_sig.decl.inputs[0].span;
 
-    let sig = tcx.bound_fn_sig(method.def_id).subst_identity();
+    let sig = tcx.fn_sig(method.def_id).subst_identity();
     let sig = tcx.liberate_late_bound_regions(method.def_id, sig);
     let sig = wfcx.normalize(span, None, sig);
 
diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs
index e253459ef64..b73a05ff398 100644
--- a/compiler/rustc_hir_analysis/src/collect.rs
+++ b/compiler/rustc_hir_analysis/src/collect.rs
@@ -1087,7 +1087,7 @@ pub fn get_infer_ret_ty<'hir>(output: &'hir hir::FnRetTy<'hir>) -> Option<&'hir
 }
 
 #[instrument(level = "debug", skip(tcx))]
-fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
+fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::EarlyBinder<ty::PolyFnSig<'_>> {
     use rustc_hir::Node::*;
     use rustc_hir::*;
 
@@ -1096,7 +1096,7 @@ fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
 
     let icx = ItemCtxt::new(tcx, def_id.to_def_id());
 
-    match tcx.hir().get(hir_id) {
+    let output = match tcx.hir().get(hir_id) {
         TraitItem(hir::TraitItem {
             kind: TraitItemKind::Fn(sig, TraitFn::Provided(_)),
             generics,
@@ -1169,7 +1169,8 @@ fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
         x => {
             bug!("unexpected sort of node in fn_sig(): {:?}", x);
         }
-    }
+    };
+    ty::EarlyBinder(output)
 }
 
 fn infer_return_ty_for_fn_sig<'tcx>(
diff --git a/compiler/rustc_hir_analysis/src/collect/type_of.rs b/compiler/rustc_hir_analysis/src/collect/type_of.rs
index 82c4aaba089..b28458fb7cf 100644
--- a/compiler/rustc_hir_analysis/src/collect/type_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/type_of.rs
@@ -868,7 +868,7 @@ fn infer_placeholder_type<'a>(
 
             match ty.kind() {
                 ty::FnDef(def_id, _) => {
-                    self.tcx.mk_fn_ptr(self.tcx.bound_fn_sig(*def_id).subst_identity())
+                    self.tcx.mk_fn_ptr(self.tcx.fn_sig(*def_id).subst_identity())
                 }
                 // FIXME: non-capturing closures should also suggest a function pointer
                 ty::Closure(..) | ty::Generator(..) => {
diff --git a/compiler/rustc_hir_analysis/src/lib.rs b/compiler/rustc_hir_analysis/src/lib.rs
index 7a359ab22fe..c2fa46e563e 100644
--- a/compiler/rustc_hir_analysis/src/lib.rs
+++ b/compiler/rustc_hir_analysis/src/lib.rs
@@ -182,7 +182,7 @@ fn require_same_types<'tcx>(
 }
 
 fn check_main_fn_ty(tcx: TyCtxt<'_>, main_def_id: DefId) {
-    let main_fnsig = tcx.bound_fn_sig(main_def_id).subst_identity();
+    let main_fnsig = tcx.fn_sig(main_def_id).subst_identity();
     let main_span = tcx.def_span(main_def_id);
 
     fn main_fn_diagnostics_def_id(tcx: TyCtxt<'_>, def_id: DefId, sp: Span) -> LocalDefId {
@@ -449,7 +449,7 @@ fn check_start_fn_ty(tcx: TyCtxt<'_>, start_def_id: DefId) {
                     ObligationCauseCode::StartFunctionType,
                 ),
                 se_ty,
-                tcx.mk_fn_ptr(tcx.bound_fn_sig(start_def_id.into()).subst_identity()),
+                tcx.mk_fn_ptr(tcx.fn_sig(start_def_id).subst_identity()),
             );
         }
         _ => {
diff --git a/compiler/rustc_hir_analysis/src/variance/constraints.rs b/compiler/rustc_hir_analysis/src/variance/constraints.rs
index b662dfca71a..2cd2b6a5f76 100644
--- a/compiler/rustc_hir_analysis/src/variance/constraints.rs
+++ b/compiler/rustc_hir_analysis/src/variance/constraints.rs
@@ -121,7 +121,7 @@ impl<'a, 'tcx> ConstraintContext<'a, 'tcx> {
             ty::FnDef(..) => {
                 self.add_constraints_from_sig(
                     current_item,
-                    tcx.bound_fn_sig(def_id.into()).subst_identity(),
+                    tcx.fn_sig(def_id).subst_identity(),
                     self.covariant,
                 );
             }