// 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 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. #![allow(unknown_features)] #![feature(box_syntax)] #![feature(box_patterns)] use std::ops::{Deref, DerefMut}; struct X(Box); static mut DESTRUCTOR_RAN: bool = false; impl Drop for X { fn drop(&mut self) { unsafe { assert!(!DESTRUCTOR_RAN); DESTRUCTOR_RAN = true; } } } impl Deref for X { type Target = isize; fn deref(&self) -> &isize { let &X(box ref x) = self; x } } impl DerefMut for X { fn deref_mut(&mut self) -> &mut isize { let &mut X(box ref mut x) = self; x } } fn main() { { let mut test = X(box 5); { let mut change = || { *test = 10 }; change(); } assert_eq!(*test, 10); } assert!(unsafe { DESTRUCTOR_RAN }); }