| // Copyright 2012 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. |
| |
| |
| #![allow(unknown_features)] |
| #![feature(box_syntax)] |
| |
| trait double { |
| fn double(self: Box<Self>) -> usize; |
| } |
| |
| impl double for Box<usize> { |
| fn double(self: Box<Box<usize>>) -> usize { **self * 2 } |
| } |
| |
| pub fn main() { |
| let x: Box<Box<Box<Box<Box<_>>>>> = box box box box box 3; |
| assert_eq!(x.double(), 6); |
| } |
