Store hir_id_to_def_id in OwnerInfo.

compiler/rustc_hir/src/definitions.rs

@@ -107,8 +107,6 @@ pub struct Definitions {
     /// Their `HirId`s are defined by their position while lowering the enclosing owner.
     // FIXME(cjgillot) Some `LocalDefId`s from `use` items are dropped during lowering and lack a `HirId`.
     pub(super) def_id_to_hir_id: IndexVec<LocalDefId, Option<hir::HirId>>,
-    /// The reverse mapping of `def_id_to_hir_id`.
-    pub(super) hir_id_to_def_id: FxHashMap<hir::HirId, LocalDefId>,
 
     /// Item with a given `LocalDefId` was defined during macro expansion with ID `ExpnId`.
     expansions_that_defined: FxHashMap<LocalDefId, ExpnId>,
@@ -330,11 +328,6 @@ impl Definitions {
         self.def_id_to_hir_id[id].unwrap()
     }
 
-    #[inline]
-    pub fn opt_hir_id_to_local_def_id(&self, hir_id: hir::HirId) -> Option<LocalDefId> {
-        self.hir_id_to_def_id.get(&hir_id).copied()
-    }
-
     /// Adds a root definition (no parent) and a few other reserved definitions.
     pub fn new(stable_crate_id: StableCrateId, crate_span: Span) -> Definitions {
         let key = DefKey {
@@ -362,7 +355,6 @@ impl Definitions {
         Definitions {
             table,
             def_id_to_hir_id: Default::default(),
-            hir_id_to_def_id: Default::default(),
             expansions_that_defined: Default::default(),
             def_id_to_span,
             stable_crate_id,
@@ -425,12 +417,6 @@ impl Definitions {
             "trying to initialize `LocalDefId` <-> `HirId` mappings twice"
         );
 
-        // Build the reverse mapping of `def_id_to_hir_id`.
-        self.hir_id_to_def_id = mapping
-            .iter_enumerated()
-            .filter_map(|(def_id, hir_id)| hir_id.map(|hir_id| (hir_id, def_id)))
-            .collect();
-
         self.def_id_to_hir_id = mapping;
     }
 

compiler/rustc_hir/src/hir.rs

@@ -707,6 +707,8 @@ pub struct OwnerNodes<'tcx> {
     pub nodes: IndexVec<ItemLocalId, Option<ParentedNode<'tcx>>>,
     /// Content of local bodies.
     pub bodies: SortedMap<ItemLocalId, &'tcx Body<'tcx>>,
+    /// Non-owning definitions contained in this owner.
+    pub local_id_to_def_id: SortedMap<ItemLocalId, LocalDefId>,
 }
 
 /// Full information resulting from lowering an AST node.

compiler/rustc_hir/src/stable_hash_impls.rs

@@ -208,8 +208,13 @@ impl<'tcx, HirCtx: crate::HashStableContext> HashStable<HirCtx> for OwnerNodes<'
     fn hash_stable(&self, hcx: &mut HirCtx, hasher: &mut StableHasher) {
         // We ignore the `nodes` and `bodies` fields since these refer to information included in
         // `hash` which is hashed in the collector and used for the crate hash.
-        let OwnerNodes { hash_including_bodies, hash_without_bodies: _, nodes: _, bodies: _ } =
-            *self;
+        let OwnerNodes {
+            hash_including_bodies,
+            hash_without_bodies: _,
+            nodes: _,
+            bodies: _,
+            local_id_to_def_id: _,
+        } = *self;
         hash_including_bodies.hash_stable(hcx, hasher);
     }
 }