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

Switch to `EarlyBinder` for `fn_sig` query

Part of the work to finish #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 }
     })
 }