fn box[T](x: &{x: T, y: T, z: T}) -> @{x: T, y: T, z: T} { ret @x; }

fn main() {
    let x: @{x: int, y: int, z: int} = box[int]({x: 1, y: 2, z: 3});
    assert (x.y == 2);
}