Directly use AttributeMap inside OwnerInfo.

compiler/rustc_hir/src/hir.rs

@@ -672,6 +672,23 @@ pub struct ParentedNode<'tcx> {
     pub node: Node<'tcx>,
 }
 
+/// Attributes owner by a HIR owner.
+#[derive(Debug)]
+pub struct AttributeMap<'tcx> {
+    pub map: BTreeMap<ItemLocalId, &'tcx [Attribute]>,
+    pub hash: Fingerprint,
+}
+
+impl<'tcx> AttributeMap<'tcx> {
+    pub const EMPTY: &'static AttributeMap<'static> =
+        &AttributeMap { map: BTreeMap::new(), hash: Fingerprint::ZERO };
+
+    #[inline]
+    pub fn get(&self, id: ItemLocalId) -> &'tcx [Attribute] {
+        self.map.get(&id).copied().unwrap_or(&[])
+    }
+}
+
 #[derive(Debug)]
 pub struct OwnerNodes<'tcx> {
     /// Pre-computed hash of the full HIR.
@@ -691,8 +708,8 @@ pub struct OwnerInfo<'hir> {
     pub nodes: OwnerNodes<'hir>,
     /// Map from each nested owner to its parent's local id.
     pub parenting: FxHashMap<LocalDefId, ItemLocalId>,
-
-    pub attrs: BTreeMap<ItemLocalId, &'hir [Attribute]>,
+    /// Collected attributes of the HIR nodes.
+    pub attrs: AttributeMap<'hir>,
     /// Map indicating what traits are in scope for places where this
     /// is relevant; generated by resolve.
     pub trait_map: FxHashMap<ItemLocalId, Box<[TraitCandidate]>>,

compiler/rustc_hir/src/lib.rs

@@ -2,6 +2,7 @@
 //!
 //! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/hir.html
 
+#![feature(const_btree_new)]
 #![feature(crate_visibility_modifier)]
 #![feature(in_band_lifetimes)]
 #![feature(once_cell)]

compiler/rustc_hir/src/stable_hash_impls.rs

@@ -1,8 +1,8 @@
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher, ToStableHashKey};
 
 use crate::hir::{
-    BodyId, Expr, ForeignItem, ForeignItemId, ImplItem, ImplItemId, Item, ItemId, Mod, OwnerNodes,
-    TraitItem, TraitItemId, Ty, VisibilityKind,
+    AttributeMap, BodyId, Expr, ForeignItem, ForeignItemId, ImplItem, ImplItemId, Item, ItemId,
+    Mod, OwnerNodes, TraitItem, TraitItemId, Ty, VisibilityKind,
 };
 use crate::hir_id::{HirId, ItemLocalId};
 use rustc_span::def_id::DefPathHash;
@@ -218,3 +218,12 @@ impl<HirCtx: crate::HashStableContext> HashStable<HirCtx> for OwnerNodes<'tcx> {
         hash.hash_stable(hcx, hasher);
     }
 }
+
+impl<HirCtx: crate::HashStableContext> HashStable<HirCtx> for AttributeMap<'tcx> {
+    fn hash_stable(&self, hcx: &mut HirCtx, hasher: &mut StableHasher) {
+        // We ignore the `map` since it refers to information included in `hash` which is hashed in
+        // the collector and used for the crate hash.
+        let AttributeMap { hash, map: _ } = *self;
+        hash.hash_stable(hcx, hasher);
+    }
+}