From dfe187d348aa74b47c4caaac112945adfd47456e Mon Sep 17 00:00:00 2001
From: ljedrz <ljedrz@gmail.com>
Date: Wed, 19 Dec 2018 17:36:39 +0100
Subject: [PATCH] query: simplify stack trimming in cycle_check

---
 src/librustc/ty/query/job.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/librustc/ty/query/job.rs b/src/librustc/ty/query/job.rs
index 4ee5ef6b1fd0..709d6201d4f5 100644
--- a/src/librustc/ty/query/job.rs
+++ b/src/librustc/ty/query/job.rs
@@ -295,7 +295,7 @@ fn cycle_check<'tcx>(query: Lrc<QueryJob<'tcx>>,
             // We detected a query cycle, fix up the initial span and return Some
 
             // Remove previous stack entries
-            stack.splice(0..p, iter::empty());
+            stack.drain(0..p);
             // Replace the span for the first query with the cycle cause
             stack[0].0 = span;
             Some(None)