Add test for the feature gate

Author: Aatch

src/liballoc/lib.rs

@@ -98,7 +98,7 @@ pub mod rc;
 /// Common out-of-memory routine
 #[cold]
 #[inline(never)]
-#[unsafe_no_nounwind]
+#[unsafe_no_unwind]
 pub fn oom() -> ! {
     // FIXME(#14674): This really needs to do something other than just abort
     //                here, but any printing done must be *guaranteed* to not

src/librustc/lint/builtin.rs

@@ -654,7 +654,7 @@ impl LintPass for UnusedAttributes {
             "omit_gdb_pretty_printer_section",
             "unsafe_no_drop_flag",
             "can_unwind",
-            "nounwind",
+            "unsafe_no_unwind",
 
             // used in resolve
             "prelude_import",

src/test/compile-fail/feature-gate-unwinding.rs

@@ -0,0 +1,17 @@
+// 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.
+
+#![allow(dead_code)]
+
+#[can_unwind]
+extern fn foo() { } //~ ERROR the `#[can_unwind]` attribute is an experimental feature
+
+#[unsafe_no_unwind]
+fn main() {} //~ ERROR the `#[unsafe_no_unwind]` attribute is an experimental feature