move item reference comment

Author: ljedrz

src/librustc/ich/impls_hir.rs

@@ -40,13 +40,6 @@ impl<'ctx> rustc_hir::HashStableContext for StableHashingContext<'ctx> {
         }
     }
 
-    // The following implementations of HashStable for `ItemId`, `TraitItemId`, and
-    // `ImplItemId` deserve special attention. Normally we do not hash `NodeId`s within
-    // the HIR, since they just signify a HIR nodes own path. But `ItemId` et al
-    // are used when another item in the HIR is *referenced* and we certainly
-    // want to pick up on a reference changing its target, so we hash the NodeIds
-    // in "DefPath Mode".
-
     fn hash_reference_to_item(&mut self, id: hir::HirId, hasher: &mut StableHasher) {
         let hcx = self;
 

src/librustc_hir/stable_hash_impls.rs

@@ -36,6 +36,13 @@ impl<HirCtx: crate::HashStableContext> HashStable<HirCtx> for BodyId {
     }
 }
 
+// The following implementations of HashStable for `ItemId`, `TraitItemId`, and
+// `ImplItemId` deserve special attention. Normally we do not hash `NodeId`s within
+// the HIR, since they just signify a HIR nodes own path. But `ItemId` et al
+// are used when another item in the HIR is *referenced* and we certainly
+// want to pick up on a reference changing its target, so we hash the NodeIds
+// in "DefPath Mode".
+
 impl<HirCtx: crate::HashStableContext> HashStable<HirCtx> for ItemId {
     fn hash_stable(&self, hcx: &mut HirCtx, hasher: &mut StableHasher) {
         hcx.hash_reference_to_item(self.id, hasher)