Clean up implementation of RPITIT assoc item lowering

4 files changed, 27 insertions, 23 deletions

diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index 3da6c6f5fe1..842d118449a 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -1079,9 +1079,11 @@ rustc_queries! {
         desc { |tcx| "comparing impl items against trait for `{}`", tcx.def_path_str(impl_id) }
     }
 
-    query associated_types_for_impl_traits_in_trait_or_impl(did: DefId) -> &'tcx ty::AssocTyForImplTraitInTraitOrImpl {
+    /// Given the `item_def_id` of a trait or impl, return a mapping from associated fn def id
+    /// to its associated type items that correspond to the RPITITs in its signature.
+    query associated_types_for_impl_traits_in_trait_or_impl(item_def_id: DefId) -> &'tcx DefIdMap<Vec<DefId>> {
         arena_cache
-        desc { |tcx| "creating rpitit for `{}`", tcx.def_path_str(did) }
+        desc { |tcx| "synthesizing RPITIT items for the opaque types for methods in `{}`", tcx.def_path_str(item_def_id) }
         separate_provide_extern
     }
 
diff --git a/compiler/rustc_middle/src/ty/assoc.rs b/compiler/rustc_middle/src/ty/assoc.rs
index 99714171c72..9534d45e495 100644
--- a/compiler/rustc_middle/src/ty/assoc.rs
+++ b/compiler/rustc_middle/src/ty/assoc.rs
@@ -1,5 +1,4 @@
 use rustc_attr_data_structures::{AttributeKind, find_attr};
-use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::sorted_map::SortedIndexMultiMap;
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Namespace};
@@ -287,22 +286,21 @@ impl AssocItems {
     }
 }
 
-#[derive(Debug, Clone, PartialEq, Encodable, Decodable, HashStable)]
-pub struct AssocTyForImplTraitInTraitOrImpl(pub FxIndexMap<DefId, Vec<DefId>>);
-
-/// Given an `fn_def_id` of a trait or a trait implementation:
-///
-/// if `fn_def_id` is a function defined inside a trait, then it synthesizes
-/// a new def id corresponding to a new associated type for each return-
-/// position `impl Trait` in the signature.
-///
-/// if `fn_def_id` is a function inside of an impl, then for each synthetic
-/// associated type generated for the corresponding trait function described
-/// above, synthesize a corresponding associated type in the impl.
-pub fn associated_types_for_impl_traits_in_associated_fn(
-    tcx: TyCtxt<'_>,
-    fn_def_id: DefId,
-) -> &'_ [DefId] {
-    let parent_def_id = tcx.parent(fn_def_id);
-    &tcx.associated_types_for_impl_traits_in_trait_or_impl(parent_def_id).0[&fn_def_id]
+impl<'tcx> TyCtxt<'tcx> {
+    /// Given an `fn_def_id` of a trait or a trait implementation:
+    ///
+    /// if `fn_def_id` is a function defined inside a trait, then it synthesizes
+    /// a new def id corresponding to a new associated type for each return-
+    /// position `impl Trait` in the signature.
+    ///
+    /// if `fn_def_id` is a function inside of an impl, then for each synthetic
+    /// associated type generated for the corresponding trait function described
+    /// above, synthesize a corresponding associated type in the impl.
+    pub fn associated_types_for_impl_traits_in_associated_fn(
+        self,
+        fn_def_id: DefId,
+    ) -> &'tcx [DefId] {
+        let parent_def_id = self.parent(fn_def_id);
+        &self.associated_types_for_impl_traits_in_trait_or_impl(parent_def_id)[&fn_def_id]
+    }
 }
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index e1b11e4f54a..0177a95498b 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -2194,7 +2194,8 @@ impl<'tcx> TyCtxt<'tcx> {
             return false;
         };
 
-        return !associated_types_for_impl_traits_in_associated_fn(self, trait_item_def_id)
+        return !self
+            .associated_types_for_impl_traits_in_associated_fn(trait_item_def_id)
             .is_empty();
     }
 }
diff --git a/compiler/rustc_middle/src/ty/parameterized.rs b/compiler/rustc_middle/src/ty/parameterized.rs
index 88f6e717af4..3d601fc0533 100644
--- a/compiler/rustc_middle/src/ty/parameterized.rs
+++ b/compiler/rustc_middle/src/ty/parameterized.rs
@@ -23,6 +23,10 @@ impl<A: ParameterizedOverTcx, B: ParameterizedOverTcx> ParameterizedOverTcx for
     type Value<'tcx> = (A::Value<'tcx>, B::Value<'tcx>);
 }
 
+impl<T: ParameterizedOverTcx> ParameterizedOverTcx for Vec<T> {
+    type Value<'tcx> = Vec<T::Value<'tcx>>;
+}
+
 impl<I: Idx + 'static, T: ParameterizedOverTcx> ParameterizedOverTcx for IndexVec<I, T> {
     type Value<'tcx> = IndexVec<I, T::Value<'tcx>>;
 }
@@ -67,7 +71,6 @@ trivially_parameterized_over_tcx! {
     crate::mir::ConstQualifs,
     ty::AsyncDestructor,
     ty::AssocItemContainer,
-    ty::AssocTyForImplTraitInTraitOrImpl,
     ty::Asyncness,
     ty::AnonConstKind,
     ty::DeducedParamAttrs,