From 5d7e283ead6305b3b44caf212de23594f3a5dd8a Mon Sep 17 00:00:00 2001
From: "Felix S. Klock II" <pnkfelix@pnkfx.org>
Date: Wed, 25 Feb 2015 01:35:41 +0100
Subject: [PATCH] Turn `unsafe_no_drop_flag` back into a gated-feature.

Fix #22173
---
 src/libsyntax/feature_gate.rs                 |  4 +++-
 .../compile-fail/unsafe_no_drop_flag-gate.rs  | 23 +++++++++++++++++++
 2 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100644 src/test/compile-fail/unsafe_no_drop_flag-gate.rs

diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs
index 32fd5b49f9a..c1865ffa9d9 100644
--- a/src/libsyntax/feature_gate.rs
+++ b/src/libsyntax/feature_gate.rs
@@ -243,7 +243,9 @@ pub static KNOWN_ATTRIBUTES: &'static [(&'static str, AttributeType)] = &[
     ("static_assert", Whitelisted),
     ("no_debug", Whitelisted),
     ("omit_gdb_pretty_printer_section", Whitelisted),
-    ("unsafe_no_drop_flag", Whitelisted),
+    ("unsafe_no_drop_flag", Gated("unsafe_no_drop_flag",
+                                  "unsafe_no_drop_flag has unstable semantics \
+                                   and may be removed in the future")),
 
     // used in resolve
     ("prelude_import", Whitelisted),
diff --git a/src/test/compile-fail/unsafe_no_drop_flag-gate.rs b/src/test/compile-fail/unsafe_no_drop_flag-gate.rs
new file mode 100644
index 00000000000..542698fd152
--- /dev/null
+++ b/src/test/compile-fail/unsafe_no_drop_flag-gate.rs
@@ -0,0 +1,23 @@
+// Copyright 2015 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.
+
+pub struct T;
+
+#[unsafe_no_drop_flag]
+//~^ ERROR unsafe_no_drop_flag has unstable semantics and may be removed
+pub struct S {
+    pub x: T,
+}
+
+impl Drop for S {
+    fn drop(&mut self) {}
+}
+
+pub fn main() {}