src/test/run-pass/nested-vec-3.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 // Test that using the `vec!` macro nested within itself works when
  12 // the contents implement Drop and we hit a panic in the middle of
  13 // construction.
  14
  15
  16 use std::thread;
  17 use std::sync::atomic::{AtomicUsize, ATOMIC_USIZE_INIT, Ordering};
  18
  19 static LOG: AtomicUsize = ATOMIC_USIZE_INIT;
  20
  21 struct D(u8);
  22
  23 impl Drop for D {
  24     fn drop(&mut self) {
  25         println!("Dropping {}", self.0);
  26         let old = LOG.load(Ordering::SeqCst);
  27         LOG.compare_and_swap(old, old << 4 | self.0 as usize, Ordering::SeqCst);
  28     }
  29 }
  30
  31 fn main() {
  32     fn die() -> D { panic!("Oh no"); }
  33     let g = thread::spawn(|| {
  34         let _nested = vec![vec![D( 1), D( 2), D( 3), D( 4)],
  35                            vec![D( 5), D( 6), D( 7), D( 8)],
  36                            vec![D( 9), D(10), die(), D(12)],
  37                            vec![D(13), D(14), D(15), D(16)]];
  38     });
  39     assert!(g.join().is_err());
  40
  41     // When the panic occurs, we will be in the midst of constructing the
  42     // second inner vector.  Therefore, we drop the elements of the
  43     // partially filled vector first, before we get around to dropping
  44     // the elements of the filled vector.
  45
  46     // Issue 23222: The order in which the elements actually get
  47     // dropped is a little funky: as noted above, we'll drop the 9+10
  48     // first, but due to #23222, they get dropped in reverse
  49     // order. Likewise, again due to #23222, we will drop the second
  50     // filled vec before the first filled vec.
  51     //
  52     // If Issue 23222 is "fixed", then presumably the corrected
  53     // expected order of events will be 0x__9_A__1_2_3_4__5_6_7_8;
  54     // that is, we would still drop 9+10 first, since they belong to
  55     // the more deeply nested expression when the panic occurs.
  56
  57     let expect = 0x__A_9__5_6_7_8__1_2_3_4;
  58     let actual = LOG.load(Ordering::SeqCst);
  59     assert!(actual == expect, "expect: 0x{:x} actual: 0x{:x}", expect, actual);
  60 }