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 // Drop works for union itself.
  12
  13 #![feature(untagged_unions)]
  14
  15 struct S;
  16
  17 union U {
  18     a: u8
  19 }
  20
  21 union W {
  22     a: S,
  23 }
  24
  25 union Y {
  26     a: S,
  27 }
  28
  29 impl Drop for S {
  30     fn drop(&mut self) {
  31         unsafe { CHECK += 10; }
  32     }
  33 }
  34
  35 impl Drop for U {
  36     fn drop(&mut self) {
  37         unsafe { CHECK += 1; }
  38     }
  39 }
  40
  41 impl Drop for W {
  42     fn drop(&mut self) {
  43         unsafe { CHECK += 1; }
  44     }
  45 }
  46
  47 static mut CHECK: u8 = 0;
  48
  49 fn main() {
  50     unsafe {
  51         assert_eq!(CHECK, 0);
  52         {
  53             let u = U { a: 1 };
  54         }
  55         assert_eq!(CHECK, 1); // 1, dtor of U is called
  56         {
  57             let w = W { a: S };
  58         }
  59         assert_eq!(CHECK, 2); // 2, not 11, dtor of S is not called
  60         {
  61             let y = Y { a: S };
  62         }
  63         assert_eq!(CHECK, 2); // 2, not 12, dtor of S is not called
  64     }
  65 }