// 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 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. #![feature(unsafe_destructor)] use std::cell::Cell; #[deriving(Show)] struct r<'a> { i: &'a Cell, } #[unsafe_destructor] impl<'a> Drop for r<'a> { fn drop(&mut self) { self.i.set(self.i.get() + 1); } } fn r(i: &Cell) -> r { r { i: i } } pub fn main() { let i = &Cell::new(0i); // Even though these look like copies, they are guaranteed not to be { let a = r(i); let b = (a, 10i); let (c, _d) = b; println!("{}", c); } assert_eq!(i.get(), 1); }