src/test/run-pass/array-slice-vec/nested-vec-3.rs

   1 // run-pass
   2 #![allow(overflowing_literals)]
   3
   4 // ignore-emscripten no threads support
   5
   6 // Test that using the `vec!` macro nested within itself works when
   7 // the contents implement Drop and we hit a panic in the middle of
   8 // construction.
   9
  10 use std::thread;
  11 use std::sync::atomic::{AtomicUsize, Ordering};
  12
  13 static LOG: AtomicUsize = AtomicUsize::new(0);
  14
  15 struct D(u8);
  16
  17 impl Drop for D {
  18     fn drop(&mut self) {
  19         println!("Dropping {}", self.0);
  20         let old = LOG.load(Ordering::SeqCst);
  21         LOG.compare_and_swap(old, old << 4 | self.0 as usize, Ordering::SeqCst);
  22     }
  23 }
  24
  25 fn main() {
  26     fn die() -> D { panic!("Oh no"); }
  27     let g = thread::spawn(|| {
  28         let _nested = vec![vec![D( 1), D( 2), D( 3), D( 4)],
  29                            vec![D( 5), D( 6), D( 7), D( 8)],
  30                            vec![D( 9), D(10), die(), D(12)],
  31                            vec![D(13), D(14), D(15), D(16)]];
  32     });
  33     assert!(g.join().is_err());
  34
  35     // When the panic occurs, we will be in the midst of constructing the
  36     // second inner vector.  Therefore, we drop the elements of the
  37     // partially filled vector first, before we get around to dropping
  38     // the elements of the filled vector.
  39
  40     // Issue 23222: The order in which the elements actually get
  41     // dropped is a little funky: as noted above, we'll drop the 9+10
  42     // first, but due to #23222, they get dropped in reverse
  43     // order. Likewise, again due to #23222, we will drop the second
  44     // filled vec before the first filled vec.
  45     //
  46     // If Issue 23222 is "fixed", then presumably the corrected
  47     // expected order of events will be 0x__9_A__1_2_3_4__5_6_7_8;
  48     // that is, we would still drop 9+10 first, since they belong to
  49     // the more deeply nested expression when the panic occurs.
  50
  51     let expect = 0x__A_9__5_6_7_8__1_2_3_4;
  52     let actual = LOG.load(Ordering::SeqCst);
  53     assert!(actual == expect, "expect: 0x{:x} actual: 0x{:x}", expect, actual);
  54 }