Auto merge of #45364 - nikomatsakis:issue-44137-anon, r=michaelwoerister

make `erase_regions_ty` query anonymous

r? @michaelwoerister

src/librustc/dep_graph/dep_node.rs

@@ -610,7 +610,14 @@ pub fn fingerprint_needed_for_crate_hash(self) -> bool {
     [] PostorderCnums,
     [] HasCloneClosures(CrateNum),
     [] HasCopyClosures(CrateNum),
-    [] EraseRegionsTy { ty: Ty<'tcx> },
+
+    // This query is not expected to have inputs -- as a result, it's
+    // not a good candidate for "replay" because it's essentially a
+    // pure function of its input (and hence the expectation is that
+    // no caller would be green **apart** from just this
+    // query). Making it anonymous avoids hashing the result, which
+    // may save a bit of time.
+    [anon] EraseRegionsTy { ty: Ty<'tcx> },
 
     [] Freevars(DefId),
     [] MaybeUnusedTraitImport(DefId),