Auto merge of #103600 - compiler-errors:early-binder-nits, r=spastorino

Address some `EarlyBinder` nits

5 files changed, 27 insertions, 45 deletions

diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs
index e4c16ef9efa..c29a3afd7fb 100644
--- a/compiler/rustc_hir_analysis/src/astconv/mod.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs
@@ -26,11 +26,9 @@ use rustc_hir::intravisit::{walk_generics, Visitor as _};
 use rustc_hir::{GenericArg, GenericArgs, OpaqueTyOrigin};
 use rustc_middle::middle::stability::AllowUnstable;
 use rustc_middle::ty::subst::{self, GenericArgKind, InternalSubsts, SubstsRef};
-use rustc_middle::ty::DynKind;
 use rustc_middle::ty::GenericParamDefKind;
-use rustc_middle::ty::{
-    self, Const, DefIdTree, EarlyBinder, IsSuggestable, Ty, TyCtxt, TypeVisitable,
-};
+use rustc_middle::ty::{self, Const, DefIdTree, IsSuggestable, Ty, TyCtxt, TypeVisitable};
+use rustc_middle::ty::{DynKind, EarlyBinder};
 use rustc_session::lint::builtin::{AMBIGUOUS_ASSOCIATED_ITEMS, BARE_TRAIT_OBJECTS};
 use rustc_span::edition::Edition;
 use rustc_span::lev_distance::find_best_match_for_name;
@@ -490,7 +488,8 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                             self.astconv
                                 .normalize_ty(
                                     self.span,
-                                    EarlyBinder(tcx.at(self.span).type_of(param.def_id))
+                                    tcx.at(self.span)
+                                        .bound_type_of(param.def_id)
                                         .subst(tcx, substs),
                                 )
                                 .into()
@@ -1255,10 +1254,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         item_segment: &hir::PathSegment<'_>,
     ) -> Ty<'tcx> {
         let substs = self.ast_path_substs_for_ty(span, did, item_segment);
-        self.normalize_ty(
-            span,
-            EarlyBinder(self.tcx().at(span).type_of(did)).subst(self.tcx(), substs),
-        )
+        self.normalize_ty(span, self.tcx().at(span).bound_type_of(did).subst(self.tcx(), substs))
     }
 
     fn conv_object_ty_poly_trait_ref(
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
index 1a4e6bf7638..150e917c739 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
@@ -22,7 +22,7 @@ use rustc_middle::ty::error::TypeError;
 use rustc_middle::ty::fold::TypeFoldable;
 use rustc_middle::ty::visit::TypeVisitable;
 use rustc_middle::ty::{
-    self, AdtKind, CanonicalUserType, DefIdTree, EarlyBinder, GenericParamDefKind, Ty, UserType,
+    self, AdtKind, CanonicalUserType, DefIdTree, GenericParamDefKind, Ty, UserType,
 };
 use rustc_middle::ty::{GenericArgKind, InternalSubsts, SubstsRef, UserSelfTy, UserSubsts};
 use rustc_session::lint;
@@ -333,22 +333,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         }
     }
 
-    /// Basically whenever we are converting from a type scheme into
-    /// the fn body space, we always want to normalize associated
-    /// types as well. This function combines the two.
-    fn instantiate_type_scheme<T>(&self, span: Span, substs: SubstsRef<'tcx>, value: T) -> T
-    where
-        T: TypeFoldable<'tcx>,
-    {
-        debug!("instantiate_type_scheme(value={:?}, substs={:?})", value, substs);
-        let value = EarlyBinder(value).subst(self.tcx, substs);
-        let result = self.normalize(span, value);
-        debug!("instantiate_type_scheme = {:?}", result);
-        result
-    }
-
-    /// As `instantiate_type_scheme`, but for the bounds found in a
-    /// generic type scheme.
+    /// Instantiates and normalizes the bounds for a given item
     pub(in super::super) fn instantiate_bounds(
         &self,
         span: Span,
@@ -1160,10 +1145,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         };
         let def_id = res.def_id();
 
-        // The things we are substituting into the type should not contain
-        // escaping late-bound regions, and nor should the base type scheme.
-        let ty = tcx.type_of(def_id);
-
         let arg_count = GenericArgCountResult {
             explicit_late_bound,
             correct: if infer_args_for_err.is_empty() {
@@ -1286,8 +1267,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 },
             )
         });
-        assert!(!substs.has_escaping_bound_vars());
-        assert!(!ty.has_escaping_bound_vars());
 
         // First, store the "user substs" for later.
         self.write_user_type_annotation_from_substs(hir_id, def_id, substs, user_self_ty);
@@ -1296,7 +1275,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         // Substitute the values for the type parameters into the type of
         // the referenced item.
-        let ty_substituted = self.instantiate_type_scheme(span, &substs, ty);
+        let ty = tcx.bound_type_of(def_id);
+        assert!(!substs.has_escaping_bound_vars());
+        assert!(!ty.0.has_escaping_bound_vars());
+        let ty_substituted = self.normalize(span, ty.subst(tcx, substs));
 
         if let Some(UserSelfTy { impl_def_id, self_ty }) = user_self_ty {
             // In the case of `Foo<T>::method` and `<Foo<T>>::method`, if `method`
@@ -1304,9 +1286,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             // type parameters, which we can infer by unifying the provided `Self`
             // with the substituted impl type.
             // This also occurs for an enum variant on a type alias.
-            let ty = tcx.type_of(impl_def_id);
-
-            let impl_ty = self.instantiate_type_scheme(span, &substs, ty);
+            let impl_ty = self.normalize(span, tcx.bound_type_of(impl_def_id).subst(tcx, substs));
             match self.at(&self.misc(span), self.param_env).eq(impl_ty, self_ty) {
                 Ok(ok) => self.register_infer_ok_obligations(ok),
                 Err(_) => {
diff --git a/compiler/rustc_hir_typeck/src/method/mod.rs b/compiler/rustc_hir_typeck/src/method/mod.rs
index 3f3af53d199..fddb8a458a7 100644
--- a/compiler/rustc_hir_typeck/src/method/mod.rs
+++ b/compiler/rustc_hir_typeck/src/method/mod.rs
@@ -456,9 +456,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         // Instantiate late-bound regions and substitute the trait
         // parameters into the method type to get the actual method type.
         //
-        // N.B., instantiate late-bound regions first so that
-        // `instantiate_type_scheme` can normalize associated types that
-        // may reference those regions.
+        // N.B., instantiate late-bound regions before normalizing the
+        // function signature so that normalization does not need to deal
+        // with bound regions.
         let fn_sig = tcx.bound_fn_sig(def_id);
         let fn_sig = fn_sig.subst(self.tcx, substs);
         let fn_sig = self.replace_bound_vars_with_fresh_vars(span, infer::FnCall, fn_sig);
diff --git a/compiler/rustc_infer/src/infer/outlives/verify.rs b/compiler/rustc_infer/src/infer/outlives/verify.rs
index 136da4a3cb1..40bbec8ddd0 100644
--- a/compiler/rustc_infer/src/infer/outlives/verify.rs
+++ b/compiler/rustc_infer/src/infer/outlives/verify.rs
@@ -5,7 +5,7 @@ use crate::infer::{GenericKind, VerifyBound};
 use rustc_data_structures::sso::SsoHashSet;
 use rustc_hir::def_id::DefId;
 use rustc_middle::ty::GenericArg;
-use rustc_middle::ty::{self, EarlyBinder, OutlivesPredicate, SubstsRef, Ty, TyCtxt};
+use rustc_middle::ty::{self, OutlivesPredicate, SubstsRef, Ty, TyCtxt};
 
 use smallvec::smallvec;
 
@@ -304,14 +304,13 @@ impl<'cx, 'tcx> VerifyBoundCx<'cx, 'tcx> {
         substs: SubstsRef<'tcx>,
     ) -> impl Iterator<Item = ty::Region<'tcx>> {
         let tcx = self.tcx;
-        let bounds = tcx.item_bounds(def_id);
-        trace!("{:#?}", bounds);
+        let bounds = tcx.bound_item_bounds(def_id);
+        trace!("{:#?}", bounds.0);
         bounds
-            .into_iter()
+            .subst_iter(tcx, substs)
             .filter_map(|p| p.to_opt_type_outlives())
             .filter_map(|p| p.no_bound_vars())
-            .map(|b| b.1)
-            .map(move |r| EarlyBinder(r).subst(tcx, substs))
+            .map(|OutlivesPredicate(_, r)| r)
     }
 
     /// Searches through a predicate list for a predicate `T: 'a`.
diff --git a/compiler/rustc_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs
index 857f52c8a24..5d0af1d4ead 100644
--- a/compiler/rustc_middle/src/ty/util.rs
+++ b/compiler/rustc_middle/src/ty/util.rs
@@ -3,6 +3,7 @@
 use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use crate::mir;
 use crate::ty::layout::IntegerExt;
+use crate::ty::query::TyCtxtAt;
 use crate::ty::{
     self, DefIdTree, FallibleTypeFolder, Ty, TyCtxt, TypeFoldable, TypeFolder, TypeSuperFoldable,
     TypeVisitable,
@@ -769,6 +770,12 @@ impl<'tcx> TyCtxt<'tcx> {
     }
 }
 
+impl<'tcx> TyCtxtAt<'tcx> {
+    pub fn bound_type_of(self, def_id: DefId) -> ty::EarlyBinder<Ty<'tcx>> {
+        ty::EarlyBinder(self.type_of(def_id))
+    }
+}
+
 struct OpaqueTypeExpander<'tcx> {
     // Contains the DefIds of the opaque types that are currently being
     // expanded. When we expand an opaque type we insert the DefId of