From 2a08860ae6ec94eccbe7b2b73fbe9d0c175196d4 Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Wed, 20 Mar 2019 01:54:53 +0000
Subject: [PATCH] Simplify `RegionConstraintCollector::vars_since_snapshot`

---
 src/librustc/infer/region_constraints/mod.rs | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/src/librustc/infer/region_constraints/mod.rs b/src/librustc/infer/region_constraints/mod.rs
index fae216c7fe7b..c0d118eed86a 100644
--- a/src/librustc/infer/region_constraints/mod.rs
+++ b/src/librustc/infer/region_constraints/mod.rs
@@ -841,12 +841,7 @@ impl<'tcx> RegionConstraintCollector<'tcx> {
     }
 
     pub fn vars_since_snapshot(&self, mark: &RegionSnapshot) -> Vec<RegionVid> {
-        self.undo_log[mark.length..]
-            .iter()
-            .filter_map(|&elt| match elt {
-                AddVar(vid) => Some(vid),
-                _ => None,
-            }).collect()
+        self.unification_table.vars_since_snapshot(&mark.region_snapshot).collect()
     }
 
     /// See [`RegionInference::region_constraints_added_in_snapshot`].