vendor/maybe-uninit/tests/doesnt_drop.rs

   1 extern crate maybe_uninit;
   2 use maybe_uninit::MaybeUninit;
   3
   4 use std::cell::Cell;
   5
   6 struct DecrementOnDrop<'a>(&'a Cell<usize>);
   7
   8 impl<'a> DecrementOnDrop<'a> {
   9     pub fn new(ref_:&'a Cell<usize>) -> Self {
  10         ref_.set(1);
  11         DecrementOnDrop(ref_)
  12     }
  13 }
  14
  15 impl<'a> Clone for DecrementOnDrop<'a> {
  16     fn clone(&self) -> Self {
  17         self.0.set(self.0.get() + 1);
  18
  19         DecrementOnDrop(self.0)
  20     }
  21 }
  22
  23 impl<'a> Drop for DecrementOnDrop<'a>{
  24     fn drop(&mut self) {
  25         self.0.set(self.0.get() - 1);
  26     }
  27 }
  28
  29 #[test]
  30 fn doesnt_drop(){
  31     let count = Cell::new(0);
  32     let arc = DecrementOnDrop::new(&count);
  33     let maybe = MaybeUninit::new(arc.clone());
  34     assert_eq!(count.get(), 2);
  35     drop(maybe);
  36     assert_eq!(count.get(), 2);
  37 }