1 files changed, 19 insertions, 3 deletions
diff --git a/compiler/rustc_hir/src/hir_id.rs b/compiler/rustc_hir/src/hir_id.rs
index 752f760ea..060f40919 100644
--- a/compiler/rustc_hir/src/hir_id.rs
+++ b/compiler/rustc_hir/src/hir_id.rs
@@ -1,5 +1,5 @@
-use crate::def_id::{DefId, LocalDefId, CRATE_DEF_ID};
-use rustc_data_structures::stable_hasher::{HashStable, StableHasher, ToStableHashKey};
+use crate::def_id::{DefId, DefIndex, LocalDefId, CRATE_DEF_ID};
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher, StableOrd, ToStableHashKey};
 use rustc_span::{def_id::DefPathHash, HashStableContext};
 use std::fmt;
 
@@ -22,6 +22,18 @@ impl OwnerId {
     }
 }
 
+impl rustc_index::vec::Idx for OwnerId {
+    #[inline]
+    fn new(idx: usize) -> Self {
+        OwnerId { def_id: LocalDefId { local_def_index: DefIndex::from_usize(idx) } }
+    }
+
+    #[inline]
+    fn index(self) -> usize {
+        self.def_id.local_def_index.as_usize()
+    }
+}
+
 impl<CTX: HashStableContext> HashStable<CTX> for OwnerId {
     #[inline]
     fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
@@ -104,7 +116,7 @@ impl Ord for HirId {
 
 impl PartialOrd for HirId {
     fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
-        Some(self.cmp(&other))
+        Some(self.cmp(other))
     }
 }
 
@@ -134,6 +146,10 @@ impl ItemLocalId {
     pub const INVALID: ItemLocalId = ItemLocalId::MAX;
 }
 
+// Safety: Ord is implement as just comparing the LocalItemId's numerical
+// values and these are not changed by (de-)serialization.
+unsafe impl StableOrd for ItemLocalId {}
+
 /// The `HirId` corresponding to `CRATE_NODE_ID` and `CRATE_DEF_ID`.
 pub const CRATE_HIR_ID: HirId =
     HirId { owner: OwnerId { def_id: CRATE_DEF_ID }, local_id: ItemLocalId::from_u32(0) };