From f7ed6e18160bc8fccf27a73c05f3935c9e8f672e Mon Sep 17 00:00:00 2001
From: Nicholas Nethercote <nnethercote@mozilla.com>
Date: Wed, 6 Feb 2019 18:02:32 +1100
Subject: [PATCH] Make an assert debug-only in
 `find_constraint_paths_between_regions`.

This reduces instruction counts for NLL builds of `wg-grammar` by over
20%.
---
 .../borrow_check/nll/region_infer/error_reporting/mod.rs        | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/librustc_mir/borrow_check/nll/region_infer/error_reporting/mod.rs b/src/librustc_mir/borrow_check/nll/region_infer/error_reporting/mod.rs
index ec68ddaf3c852..550668a7ceece 100644
--- a/src/librustc_mir/borrow_check/nll/region_infer/error_reporting/mod.rs
+++ b/src/librustc_mir/borrow_check/nll/region_infer/error_reporting/mod.rs
@@ -205,7 +205,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             for constraint in self.constraint_graph
                 .outgoing_edges(r, &self.constraints, fr_static)
             {
-                assert_eq!(constraint.sup, r);
+                debug_assert_eq!(constraint.sup, r);
                 let sub_region = constraint.sub;
                 if let Trace::NotVisited = context[sub_region] {
                     context[sub_region] = Trace::FromOutlivesConstraint(constraint);