Add regression test for issue #16739

Author: bkoropoff

Diff for: src/test/run-pass/issue-16739.rs

@@ -0,0 +1,42 @@
+// Copyright 2014 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.
+
+#![feature(unboxed_closures)]
+
+// Test that unboxing shim for calling rust-call ABI methods through a
+// trait box works and does not cause an ICE
+
+struct Foo { foo: uint }
+
+impl FnOnce<(), uint> for Foo {
+    #[rust_call_abi_hack]
+    fn call_once(self, _: ()) -> uint { self.foo }
+}
+
+impl FnOnce<(uint,), uint> for Foo {
+    #[rust_call_abi_hack]
+    fn call_once(self, (x,): (uint,)) -> uint { self.foo + x }
+}
+
+impl FnOnce<(uint, uint), uint> for Foo {
+    #[rust_call_abi_hack]
+    fn call_once(self, (x, y): (uint, uint)) -> uint { self.foo + x + y }
+}
+
+fn main() {
+    let f = box Foo { foo: 42 } as Box<FnOnce<(), uint>>;
+    assert_eq!(f.call_once(()), 42);
+
+    let f = box Foo { foo: 40 } as Box<FnOnce<(uint,), uint>>;
+    assert_eq!(f.call_once((2,)), 42);
+
+    let f = box Foo { foo: 40 } as Box<FnOnce<(uint, uint), uint>>;
+    assert_eq!(f.call_once((1, 1)), 42);
+}