Auto merge of rust-lang#107055 - kylematsuda:eb-fn-sig, r=lcnr

Switch to `EarlyBinder` for `fn_sig` query

Part of the work to finish rust-lang#105779 (also see rust-lang/types-team#78).

Several queries `X` have a `bound_X` variant that wraps the output in [`EarlyBinder`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/subst/struct.EarlyBinder.html). This adds `EarlyBinder` to the return type of the `fn_sig` query and removes `bound_fn_sig`.

r? `@lcnr`

Author: bors

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -2599,7 +2599,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 match ty.kind() {
                     ty::FnDef(_, _) | ty::FnPtr(_) => self.annotate_fn_sig(
                         self.mir_def_id(),
-                        self.infcx.tcx.fn_sig(self.mir_def_id()),
+                        self.infcx.tcx.fn_sig(self.mir_def_id()).subst_identity(),
                     ),
                     _ => None,
                 }

compiler/rustc_borrowck/src/diagnostics/mod.rs

@@ -1064,7 +1064,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                         );
                     }
                 }
-                CallKind::Normal { self_arg, desugaring, method_did } => {
+                CallKind::Normal { self_arg, desugaring, method_did, method_substs } => {
                     let self_arg = self_arg.unwrap();
                     let tcx = self.infcx.tcx;
                     if let Some((CallDesugaringKind::ForLoopIntoIter, _)) = desugaring {
@@ -1136,7 +1136,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                             && let self_ty = infcx.replace_bound_vars_with_fresh_vars(
                                 fn_call_span,
                                 LateBoundRegionConversionTime::FnCall,
-                                tcx.fn_sig(method_did).input(0),
+                                tcx.fn_sig(method_did).subst(tcx, method_substs).input(0),
                             )
                             && infcx.can_eq(self.param_env, ty, self_ty).is_ok()
                         {

compiler/rustc_borrowck/src/universal_regions.rs

@@ -472,7 +472,7 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
         // C-variadic fns also have a `VaList` input that's not listed in the signature
         // (as it's created inside the body itself, not passed in from outside).
         if let DefiningTy::FnDef(def_id, _) = defining_ty {
-            if self.infcx.tcx.fn_sig(def_id).c_variadic() {
+            if self.infcx.tcx.fn_sig(def_id).skip_binder().c_variadic() {
                 let va_list_did = self.infcx.tcx.require_lang_item(
                     LangItem::VaList,
                     Some(self.infcx.tcx.def_span(self.mir_def.did)),
@@ -665,7 +665,7 @@ impl<'cx, 'tcx> UniversalRegionsBuilder<'cx, 'tcx> {
             }
 
             DefiningTy::FnDef(def_id, _) => {
-                let sig = tcx.fn_sig(def_id);
+                let sig = tcx.fn_sig(def_id).subst_identity();
                 let sig = indices.fold_to_region_vids(tcx, sig);
                 sig.inputs_and_output()
             }

compiler/rustc_codegen_cranelift/src/main_shim.rs

@@ -46,7 +46,7 @@ pub(crate) fn maybe_create_entry_wrapper(
         is_main_fn: bool,
         sigpipe: u8,
     ) {
-        let main_ret_ty = tcx.fn_sig(rust_main_def_id).output();
+        let main_ret_ty = tcx.fn_sig(rust_main_def_id).no_bound_vars().unwrap().output();
         // Given that `main()` has no arguments,
         // then its return type cannot have
         // late-bound regions, since late-bound

compiler/rustc_codegen_llvm/src/attributes.rs

@@ -441,7 +441,7 @@ pub fn from_fn_attrs<'ll, 'tcx>(
         // the WebAssembly specification, which has this feature. This won't be
         // needed when LLVM enables this `multivalue` feature by default.
         if !cx.tcx.is_closure(instance.def_id()) {
-            let abi = cx.tcx.fn_sig(instance.def_id()).abi();
+            let abi = cx.tcx.fn_sig(instance.def_id()).skip_binder().abi();
             if abi == Abi::Wasm {
                 function_features.push("+multivalue".to_string());
             }

compiler/rustc_codegen_ssa/src/base.rs

@@ -436,7 +436,7 @@ pub fn maybe_create_entry_wrapper<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
             cx.type_func(&[], cx.type_int())
         };
 
-        let main_ret_ty = cx.tcx().fn_sig(rust_main_def_id).output();
+        let main_ret_ty = cx.tcx().fn_sig(rust_main_def_id).no_bound_vars().unwrap().output();
         // Given that `main()` has no arguments,
         // then its return type cannot have
         // late-bound regions, since late-bound

compiler/rustc_codegen_ssa/src/codegen_attrs.rs

@@ -214,7 +214,7 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: DefId) -> CodegenFnAttrs {
             }
         } else if attr.has_name(sym::cmse_nonsecure_entry) {
             if validate_fn_only_attr(attr.span)
-                && !matches!(tcx.fn_sig(did).abi(), abi::Abi::C { .. })
+                && !matches!(tcx.fn_sig(did).skip_binder().abi(), abi::Abi::C { .. })
             {
                 struct_span_err!(
                     tcx.sess,
@@ -234,7 +234,7 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: DefId) -> CodegenFnAttrs {
         } else if attr.has_name(sym::track_caller) {
             if !tcx.is_closure(did.to_def_id())
                 && validate_fn_only_attr(attr.span)
-                && tcx.fn_sig(did).abi() != abi::Abi::Rust
+                && tcx.fn_sig(did).skip_binder().abi() != abi::Abi::Rust
             {
                 struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI")
                     .emit();
@@ -266,7 +266,7 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: DefId) -> CodegenFnAttrs {
             }
         } else if attr.has_name(sym::target_feature) {
             if !tcx.is_closure(did.to_def_id())
-                && tcx.fn_sig(did).unsafety() == hir::Unsafety::Normal
+                && tcx.fn_sig(did).skip_binder().unsafety() == hir::Unsafety::Normal
             {
                 if tcx.sess.target.is_like_wasm || tcx.sess.opts.actually_rustdoc {
                     // The `#[target_feature]` attribute is allowed on

compiler/rustc_const_eval/src/const_eval/fn_queries.rs

@@ -66,7 +66,7 @@ fn is_promotable_const_fn(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
                 if cfg!(debug_assertions) && stab.promotable {
                     let sig = tcx.fn_sig(def_id);
                     assert_eq!(
-                        sig.unsafety(),
+                        sig.skip_binder().unsafety(),
                         hir::Unsafety::Normal,
                         "don't mark const unsafe fns as promotable",
                         // https://github.com/rust-lang/rust/pull/53851#issuecomment-418760682

compiler/rustc_const_eval/src/transform/check_consts/mod.rs

@@ -72,7 +72,7 @@ impl<'mir, 'tcx> ConstCx<'mir, 'tcx> {
             let ty::Closure(_, substs) = ty.kind() else { bug!("type_of closure not ty::Closure") };
             substs.as_closure().sig()
         } else {
-            self.tcx.fn_sig(did)
+            self.tcx.fn_sig(did).subst_identity()
         }
     }
 }

compiler/rustc_const_eval/src/util/call_kind.rs

@@ -40,6 +40,7 @@ pub enum CallKind<'tcx> {
         self_arg: Option<Ident>,
         desugaring: Option<(CallDesugaringKind, Ty<'tcx>)>,
         method_did: DefId,
+        method_substs: SubstsRef<'tcx>,
     },
     /// A call to `Fn(..)::call(..)`, desugared from `my_closure(a, b, c)`
     FnCall { fn_trait_id: DefId, self_ty: Ty<'tcx> },
@@ -131,6 +132,6 @@ pub fn call_kind<'tcx>(
         } else {
             None
         };
-        CallKind::Normal { self_arg, desugaring, method_did }
+        CallKind::Normal { self_arg, desugaring, method_did, method_substs }
     })
 }

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)),
         );

compiler/rustc_hir_analysis/src/check/compare_impl_item.rs

@@ -249,15 +249,15 @@ fn compare_method_predicate_entailment<'tcx>(
     let unnormalized_impl_sig = infcx.replace_bound_vars_with_fresh_vars(
         impl_m_span,
         infer::HigherRankedType,
-        tcx.fn_sig(impl_m.def_id),
+        tcx.fn_sig(impl_m.def_id).subst_identity(),
     );
     let unnormalized_impl_fty = tcx.mk_fn_ptr(ty::Binder::dummy(unnormalized_impl_sig));
 
     let norm_cause = ObligationCause::misc(impl_m_span, impl_m_def_id);
     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.fn_sig(trait_m.def_id).bound_vars(),
-        tcx.fn_sig(impl_m.def_id).bound_vars(),
+        tcx.fn_sig(trait_m.def_id).skip_binder().bound_vars(),
+        tcx.fn_sig(impl_m.def_id).skip_binder().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.fn_sig(impl_m.def_id).skip_binder().output().kind() {
+        match tcx.fn_sig(impl_m.def_id).skip_binder().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.fn_sig(impl_m.def_id),
+            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.fn_sig(method.def_id).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();
@@ -1350,8 +1350,8 @@ fn compare_number_of_method_arguments<'tcx>(
 ) -> Result<(), ErrorGuaranteed> {
     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.inputs().skip_binder().len();
-    let impl_number_args = impl_m_fty.inputs().skip_binder().len();
+    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();
 
     if trait_number_args != impl_number_args {
         let trait_span = trait_m

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.fn_sig(it.owner_id)), fty);
+        require_same_types(
+            tcx,
+            &cause,
+            tcx.mk_fn_ptr(tcx.fn_sig(it.owner_id).subst_identity()),
+            fty,
+        );
     }
 }
 

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.fn_sig(assoc.def_id).skip_binder(),
+                tcx.fn_sig(assoc.def_id).subst_identity().skip_binder(),
                 assoc.ident(tcx),
                 tcx.predicates_of(assoc.def_id),
                 assoc,

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.fn_sig(item_def_id),
+                            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.fn_sig(item.def_id);
+                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.fn_sig(def_id);
+        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.fn_sig(method.def_id);
+    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);
 

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>(

compiler/rustc_hir_analysis/src/collect/type_of.rs

@@ -867,7 +867,9 @@ fn infer_placeholder_type<'a>(
             }
 
             match ty.kind() {
-                ty::FnDef(def_id, _) => self.tcx.mk_fn_ptr(self.tcx.fn_sig(*def_id)),
+                ty::FnDef(def_id, substs) => {
+                    self.tcx.mk_fn_ptr(self.tcx.fn_sig(*def_id).subst(self.tcx, substs))
+                }
                 // FIXME: non-capturing closures should also suggest a function pointer
                 ty::Closure(..) | ty::Generator(..) => {
                     self.success = false;

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.fn_sig(main_def_id);
+    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.fn_sig(start_def_id)),
+                tcx.mk_fn_ptr(tcx.fn_sig(start_def_id).subst_identity()),
             );
         }
         _ => {

compiler/rustc_hir_analysis/src/variance/constraints.rs

@@ -119,7 +119,11 @@ impl<'a, 'tcx> ConstraintContext<'a, 'tcx> {
             }
 
             ty::FnDef(..) => {
-                self.add_constraints_from_sig(current_item, tcx.fn_sig(def_id), self.covariant);
+                self.add_constraints_from_sig(
+                    current_item,
+                    tcx.fn_sig(def_id).subst_identity(),
+                    self.covariant,
+                );
             }
 
             ty::Error(_) => {}

compiler/rustc_hir_typeck/src/callee.rs

@@ -367,7 +367,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     ) -> Ty<'tcx> {
         let (fn_sig, def_id) = match *callee_ty.kind() {
             ty::FnDef(def_id, subst) => {
-                let fn_sig = self.tcx.bound_fn_sig(def_id).subst(self.tcx, subst);
+                let fn_sig = self.tcx.fn_sig(def_id).subst(self.tcx, subst);
 
                 // Unit testing: function items annotated with
                 // `#[rustc_evaluate_where_clauses]` trigger special output