Store hir_id_to_def_id in OwnerInfo.

compiler/rustc_ast_lowering/src/lib.rs

@@ -479,6 +479,16 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         let attrs = std::mem::take(&mut self.attrs);
         let mut bodies = std::mem::take(&mut self.bodies);
         let local_node_ids = std::mem::take(&mut self.local_node_ids);
+
+        let local_id_to_def_id = local_node_ids
+            .iter()
+            .filter_map(|&node_id| {
+                let def_id = self.resolver.opt_local_def_id(node_id)?;
+                let hir_id = self.node_id_to_hir_id[node_id]?;
+                Some((hir_id.local_id, def_id))
+            })
+            .collect();
+
         let trait_map = local_node_ids
             .into_iter()
             .filter_map(|node_id| {
@@ -501,7 +511,13 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         let (hash_including_bodies, hash_without_bodies) = self.hash_owner(node, &bodies);
         let (nodes, parenting) =
             index::index_hir(self.sess, self.resolver.definitions(), node, &bodies);
-        let nodes = hir::OwnerNodes { hash_including_bodies, hash_without_bodies, nodes, bodies };
+        let nodes = hir::OwnerNodes {
+            hash_including_bodies,
+            hash_without_bodies,
+            nodes,
+            bodies,
+            local_id_to_def_id,
+        };
         let attrs = {
             let mut hcx = self.resolver.create_stable_hashing_context();
             let mut stable_hasher = StableHasher::new();

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: _ } =
+        let OwnerNodes {
-            *self;
+            hash_including_bodies,
+            hash_without_bodies: _,
+            nodes: _,
+            bodies: _,
+            local_id_to_def_id: _,
+        } = *self;
         hash_including_bodies.hash_stable(hcx, hasher);
     }
 }

compiler/rustc_middle/src/hir/map/mod.rs

@@ -204,8 +204,11 @@ impl<'hir> Map<'hir> {
         if hir_id.local_id == ItemLocalId::new(0) {
             Some(hir_id.owner)
         } else {
-            // FIXME(#85914) is this access safe for incr. comp.?
+            self.tcx
-            self.tcx.untracked_resolutions.definitions.opt_hir_id_to_local_def_id(hir_id)
+                .hir_owner_nodes(hir_id.owner)?
+                .local_id_to_def_id
+                .get(&hir_id.local_id)
+                .copied()
         }
     }