--- /dev/null
+// 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.
+
+// Given `<expr> as Box<Trait>`, we should be able to infer that a
+// `Box<_>` is the expected type.
+
+trait Foo { fn foo(&self) -> u32; }
+impl Foo for u32 { fn foo(&self) -> u32 { *self } }
+
+// (another impl to ensure trait-matching cannot just choose from a singleton set)
+impl Foo for () { fn foo(&self) -> u32 { -176 } }
+
+trait Boxed { fn make() -> Self; }
+impl Boxed for Box<u32> { fn make() -> Self { Box::new(7) } }
+
+// (another impl to ensure trait-matching cannot just choose from a singleton set)
+impl Boxed for () { fn make() -> Self { () } }
+
+fn boxed_foo() {
+ let b7 = Boxed::make() as Box<Foo>;
+ assert_eq!(b7.foo(), 7);
+}
+
+trait Refed<'a,T> { fn make(&'a T) -> Self; }
+impl<'a> Refed<'a, u32> for &'a u32 { fn make(x: &'a u32) -> Self { x } }
+
+// (another impl to ensure trait-matching cannot just choose from a singleton set)
+impl<'a,'b> Refed<'a, ()> for &'b () { fn make(_: &'a ()) -> Self { static U: () = (); &U } }
+
+fn refed_foo() {
+ let a = 8;
+ let b7 = Refed::make(&a) as &Foo;
+ assert_eq!(b7.foo(), 8);
+}
+
+fn check_subtyping_works() {
+ fn inner<'short, 'long:'short>(_s: &'short u32,
+ l: &'long u32) -> &'short (Foo+'short) {
+ Refed::make(l) as &Foo
+ }
+
+ let a = 9;
+ let b = 10;
+ let r = inner(&b, &a);
+ assert_eq!(r.foo(), 9);
+}
+
+pub fn main() {
+ boxed_foo();
+ refed_foo();
+ check_subtyping_works();
+}