From cd8de5426e7fa5d2a290ff1e882d25b0e0f5caff Mon Sep 17 00:00:00 2001
From: vagrant <vagrant@rust-lang.dev>
Date: Sat, 9 Jan 2016 23:30:33 +0000
Subject: [PATCH] Show clearer error message when #![deny(warnings)] escalates
 a warning

Addresses #30730
---
 src/librustc/lint/context.rs | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/librustc/lint/context.rs b/src/librustc/lint/context.rs
index 08fba2dc56fe..122b2ab73de9 100644
--- a/src/librustc/lint/context.rs
+++ b/src/librustc/lint/context.rs
@@ -451,9 +451,14 @@ pub trait LintContext: Sized {
 
     fn level_src(&self, lint: &'static Lint) -> Option<LevelSource> {
         self.lints().levels.get(&LintId::of(lint)).map(|ls| match ls {
-            &(Warn, src) => {
+            &(Warn, _) => {
                 let lint_id = LintId::of(builtin::WARNINGS);
-                (self.lints().get_level_source(lint_id).0, src)
+                let warn_src = self.lints().get_level_source(lint_id);
+                if warn_src.0 != Warn {
+                    warn_src
+                } else {
+                    *ls
+                }
             }
             _ => *ls
         })