From b5e2451f62391223cd9db7d025bf3a1d67713adc Mon Sep 17 00:00:00 2001
From: Niko Matsakis <niko@alum.mit.edu>
Date: Wed, 18 Oct 2017 11:21:36 -0400
Subject: [PATCH] make `erase_regions_ty` query anonymous

---
 src/librustc/dep_graph/dep_node.rs | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/librustc/dep_graph/dep_node.rs b/src/librustc/dep_graph/dep_node.rs
index f9e902b910504..6993ef3768a79 100644
--- a/src/librustc/dep_graph/dep_node.rs
+++ b/src/librustc/dep_graph/dep_node.rs
@@ -610,7 +610,14 @@ define_dep_nodes!( <'tcx>
     [] 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),