src/test/run-pass/union/union-drop.rs

   1 // Copyright 2016 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 // run-pass
  12 #![allow(dead_code)]
  13 #![allow(unused_variables)]
  14 #![allow(unions_with_drop_fields)]
  15
  16 // Drop works for union itself.
  17
  18 #![feature(untagged_unions)]
  19
  20 struct S;
  21
  22 union U {
  23     a: u8
  24 }
  25
  26 union W {
  27     a: S,
  28 }
  29
  30 union Y {
  31     a: S,
  32 }
  33
  34 impl Drop for S {
  35     fn drop(&mut self) {
  36         unsafe { CHECK += 10; }
  37     }
  38 }
  39
  40 impl Drop for U {
  41     fn drop(&mut self) {
  42         unsafe { CHECK += 1; }
  43     }
  44 }
  45
  46 impl Drop for W {
  47     fn drop(&mut self) {
  48         unsafe { CHECK += 1; }
  49     }
  50 }
  51
  52 static mut CHECK: u8 = 0;
  53
  54 fn main() {
  55     unsafe {
  56         assert_eq!(CHECK, 0);
  57         {
  58             let u = U { a: 1 };
  59         }
  60         assert_eq!(CHECK, 1); // 1, dtor of U is called
  61         {
  62             let w = W { a: S };
  63         }
  64         assert_eq!(CHECK, 2); // 2, not 11, dtor of S is not called
  65         {
  66             let y = Y { a: S };
  67         }
  68         assert_eq!(CHECK, 2); // 2, not 12, dtor of S is not called
  69     }
  70 }