| // 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. |
| |
| #![allow(dead_code)] |
| |
| use std::cell::Cell; |
| |
| #[derive(Copy)] |
| struct Foo { |
| x: isize |
| } |
| |
| impl Clone for Foo { |
| fn clone(&self) -> Foo { |
| // Using Cell in any way should never cause clone() to be |
| // invoked -- after all, that would permit evil user code to |
| // abuse `Cell` and trigger crashes. |
| |
| panic!(); |
| } |
| } |
| |
| pub fn main() { |
| let x = Cell::new(Foo { x: 22 }); |
| let _y = x.get(); |
| let _z = x.clone(); |
| } |