Store def_id_to_hir_id as variant in hir_owner.

If hir_owner is Owner(_), the LocalDefId is pointing to an owner, so the ItemLocalId is 0.
If the HIR node does not exist, we store Phantom.
Otherwise, we store the HirId associated to the LocalDefId.

1 files changed, 11 insertions, 18 deletions

diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index 32cec3a295a..f21f0b895ad 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -98,7 +98,7 @@ struct LoweringContext<'a, 'hir: 'a> {
     arena: &'hir Arena<'hir>,
 
     /// The items being lowered are collected here.
-    owners: IndexVec<LocalDefId, Option<hir::OwnerInfo<'hir>>>,
+    owners: IndexVec<LocalDefId, hir::MaybeOwner<&'hir hir::OwnerInfo<'hir>>>,
     /// Bodies inside the owner being lowered.
     bodies: Vec<(hir::ItemLocalId, &'hir hir::Body<'hir>)>,
     /// Attributes inside the owner being lowered.
@@ -291,7 +291,8 @@ pub fn lower_crate<'a, 'hir>(
 ) -> &'hir hir::Crate<'hir> {
     let _prof_timer = sess.prof.verbose_generic_activity("hir_lowering");
 
-    let owners = IndexVec::from_fn_n(|_| None, resolver.definitions().def_index_count());
+    let owners =
+        IndexVec::from_fn_n(|_| hir::MaybeOwner::Phantom, resolver.definitions().def_index_count());
     LoweringContext {
         sess,
         resolver,
@@ -402,19 +403,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
 
         let hir_hash = self.compute_hir_hash();
 
-        let mut def_id_to_hir_id = IndexVec::default();
-
-        for (node_id, hir_id) in self.node_id_to_hir_id.into_iter_enumerated() {
-            if let Some(def_id) = self.resolver.opt_local_def_id(node_id) {
-                if def_id_to_hir_id.len() <= def_id.index() {
-                    def_id_to_hir_id.resize(def_id.index() + 1, None);
-                }
-                def_id_to_hir_id[def_id] = hir_id;
-            }
-        }
-
-        self.resolver.definitions().init_def_id_to_hir_id_mapping(def_id_to_hir_id);
-
         let krate = hir::Crate { owners: self.owners, hir_hash };
         self.arena.alloc(krate)
     }
@@ -427,7 +415,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             .owners
             .iter_enumerated()
             .filter_map(|(def_id, info)| {
-                let info = info.as_ref()?;
+                let info = info.as_owner()?;
                 let def_path_hash = definitions.def_path_hash(def_id);
                 Some((def_path_hash, info))
             })
@@ -469,8 +457,8 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         self.current_hir_id_owner = current_owner;
         self.item_local_id_counter = current_local_counter;
 
-        let _old = self.owners.insert(def_id, info);
-        debug_assert!(_old.is_none());
+        self.owners.ensure_contains_elem(def_id, || hir::MaybeOwner::Phantom);
+        self.owners[def_id] = hir::MaybeOwner::Owner(self.arena.alloc(info));
 
         def_id
     }
@@ -488,6 +476,11 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     None
                 } else {
                     let def_id = self.resolver.opt_local_def_id(node_id)?;
+                    self.owners.ensure_contains_elem(def_id, || hir::MaybeOwner::Phantom);
+                    if let o @ hir::MaybeOwner::Phantom = &mut self.owners[def_id] {
+                        // Do not override a `MaybeOwner::Owner` that may already here.
+                        *o = hir::MaybeOwner::NonOwner(hir_id);
+                    }
                     Some((hir_id.local_id, def_id))
                 }
             })