From 0190286d488365e033fa9210188b15fc46e22764 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Re=CC=81my=20Rakic?= <remy.rakic@gmail.com>
Date: Wed, 4 Jul 2018 00:31:12 +0200
Subject: [PATCH] NLL Liveness: Skip regionless types when visiting free
 regions

The tuple-stress benchmark exercises the liveness constraint generation code for types which do not have regions
---
 src/librustc/ty/fold.rs | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/librustc/ty/fold.rs b/src/librustc/ty/fold.rs
index f55a512908499..a933d7e6de8b7 100644
--- a/src/librustc/ty/fold.rs
+++ b/src/librustc/ty/fold.rs
@@ -307,6 +307,15 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
 
                 false // keep visiting
             }
+
+            fn visit_ty(&mut self, ty: Ty<'tcx>) -> bool {
+                // We're only interested in types involving regions
+                if ty.flags.intersects(TypeFlags::HAS_FREE_REGIONS) {
+                    ty.super_visit_with(self)
+                } else {
+                    false // keep visiting
+                }
+            }
         }
     }
 }