Add codegen test to make sure that closures are 'internalized' properly.

src/test/codegen/internalize-closures.rs

@@ -0,0 +1,20 @@
+// 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.
+
+// compile-flags: -C no-prepopulate-passes
+
+pub fn main() {
+
+    // We want to make sure that closures get 'internal' linkage instead of
+    // 'weak_odr' when they are not shared between codegen units
+    // CHECK: define internal {{.*}}_ZN20internalize_closures4main{{.*}}$u7b$$u7b$closure$u7d$$u7d$
+    let c = |x:i32| { x + 1 };
+    let _ = c(1);
+}