// Copyright 2016 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. // Drop works for union itself. #![feature(untagged_unions)] struct S; union U { a: S } impl Drop for S { fn drop(&mut self) { unsafe { CHECK += 10; } } } impl Drop for U { fn drop(&mut self) { unsafe { CHECK += 1; } } } static mut CHECK: u8 = 0; fn main() { unsafe { let mut u = U { a: S }; assert_eq!(CHECK, 0); u = U { a: S }; assert_eq!(CHECK, 1); // union itself is assigned, union is dropped, field is not dropped u.a = S; assert_eq!(CHECK, 11); // union field is assigned, field is dropped } }