From c0636ab087927152ed9dfdb0f532429f1626f57f Mon Sep 17 00:00:00 2001
From: Nicholas Nethercote <nnethercote@mozilla.com>
Date: Tue, 21 Aug 2018 18:06:55 +1000
Subject: [PATCH] Avoid some Place clones.

This is a 0.5% speedup on ripgrep.
---
 src/librustc_mir/borrow_check/mod.rs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/librustc_mir/borrow_check/mod.rs b/src/librustc_mir/borrow_check/mod.rs
index ce0e76a636db2..9d5be714ac7bb 100644
--- a/src/librustc_mir/borrow_check/mod.rs
+++ b/src/librustc_mir/borrow_check/mod.rs
@@ -1080,7 +1080,10 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
             }
         }
 
-        if self
+        // Check is_empty() first because it's the common case, and doing that
+        // way we avoid the clone() call.
+        if !self.access_place_error_reported.is_empty() &&
+           self
             .access_place_error_reported
             .contains(&(place_span.0.clone(), place_span.1))
         {