testsuite: Test for #6132

Closes #6132

src/test/compile-fail/attrs-after-extern-mod.rs

@@ -0,0 +1,24 @@
+// Copyright 2013 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.
+
+// Constants (static variables) can be used to match in patterns, but mutable
+// statics cannot. This ensures that there's some form of error if this is
+// attempted.
+
+use std::libc;
+
+#[nolink]
+extern {
+    static mut debug_static_mut: libc::c_int;
+    pub fn debug_static_mut_check_four();
+    #[cfg(stage37)] //~ ERROR expected item after attributes
+}
+
+pub fn main() {}