src/test/ui/destructuring-assignment/drop-order.rs

   1 // run-pass
   2
   3 //! Test that let bindings and destructuring assignments have consistent drop orders
   4
   5 #![allow(unused_variables, unused_assignments)]
   6
   7 use std::cell::RefCell;
   8
   9 thread_local! {
  10     static DROP_ORDER: RefCell<Vec<usize>> = RefCell::new(Vec::new());
  11 }
  12
  13 struct DropRecorder(usize);
  14 impl Drop for DropRecorder {
  15     fn drop(&mut self) {
  16         DROP_ORDER.with(|d| d.borrow_mut().push(self.0));
  17     }
  18 }
  19
  20 fn main() {
  21     let expected_drop_order = vec![1, 4, 5, 3, 2];
  22     // Check the drop order for let bindings:
  23     {
  24         let _ = DropRecorder(1);
  25         let _val = DropRecorder(2);
  26         let (x, _) = (DropRecorder(3), DropRecorder(4));
  27         drop(DropRecorder(5));
  28     }
  29     DROP_ORDER.with(|d| {
  30         assert_eq!(&*d.borrow(), &expected_drop_order);
  31         d.borrow_mut().clear();
  32     });
  33     // Check that the drop order for destructuring assignment is the same:
  34     {
  35         let _val;
  36         let x;
  37         _ = DropRecorder(1);
  38         _val = DropRecorder(2);
  39         (x, _) = (DropRecorder(3), DropRecorder(4));
  40         drop(DropRecorder(5));
  41     }
  42     DROP_ORDER.with(|d| assert_eq!(&*d.borrow(), &expected_drop_order));
  43 }