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]>>,