src/test/run-pass/issues/issue-25549-multiple-drop.rs

   1 // Copyright 2015 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(unused_variables)]
  13 struct Foo<'r>(&'r mut i32);
  14
  15 impl<'r> Drop for Foo<'r> {
  16     fn drop(&mut self) {
  17         *self.0 += 1;
  18     }
  19 }
  20
  21 trait Trait {}
  22 impl<'r> Trait for Foo<'r> {}
  23
  24 struct Holder<T: ?Sized>(T);
  25
  26 fn main() {
  27     let mut drops = 0;
  28
  29     {
  30         let y = &Holder([Foo(&mut drops)]) as &Holder<[Foo]>;
  31         // this used to cause an extra drop of the Foo instance
  32         let x = &y.0;
  33     }
  34     assert_eq!(1, drops);
  35
  36     drops = 0;
  37     {
  38         let y = &Holder(Foo(&mut drops)) as &Holder<Trait>;
  39         // this used to cause an extra drop of the Foo instance
  40         let x = &y.0;
  41     }
  42     assert_eq!(1, drops);
  43 }