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 1/3] 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 08fba2dc56f..122b2ab73de 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
         })

From ab52327a8303a658bd722f6bb4840c2a002338b9 Mon Sep 17 00:00:00 2001
From: Joshua Holmer <jholmer.in@gmail.com>
Date: Tue, 12 Jan 2016 15:05:08 +0000
Subject: [PATCH 2/3] Add compile fail test for #30730

---
 src/test/compile-fail/issue-30730.rs | 13 +++++++++++++
 1 file changed, 13 insertions(+)
 create mode 100644 src/test/compile-fail/issue-30730.rs

diff --git a/src/test/compile-fail/issue-30730.rs b/src/test/compile-fail/issue-30730.rs
new file mode 100644
index 00000000000..80656ccdb6d
--- /dev/null
+++ b/src/test/compile-fail/issue-30730.rs
@@ -0,0 +1,13 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![deny(warnings)]
+use std::thread; //~ ERROR: unused import
+fn main() {}

From a5bdc43a46fb02faeec64fd13b67db11197cef97 Mon Sep 17 00:00:00 2001
From: Joshua Holmer <jholmer.in@gmail.com>
Date: Tue, 12 Jan 2016 15:16:43 +0000
Subject: [PATCH 3/3] Improve previous compile fail test

---
 src/test/compile-fail/issue-30730.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/test/compile-fail/issue-30730.rs b/src/test/compile-fail/issue-30730.rs
index 80656ccdb6d..82804bb7474 100644
--- a/src/test/compile-fail/issue-30730.rs
+++ b/src/test/compile-fail/issue-30730.rs
@@ -8,6 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![deny(warnings)]
+#![deny(warnings)] //~ NOTE: lint level defined here
 use std::thread; //~ ERROR: unused import
 fn main() {}