diff --git a/src/libcore/tests/array.rs b/src/libcore/tests/array.rs index c2a816f0a7d90..4bc44e98fc802 100644 --- a/src/libcore/tests/array.rs +++ b/src/libcore/tests/array.rs @@ -241,3 +241,52 @@ fn iterator_drops() { } assert_eq!(i.get(), 5); } + +// This test does not work on targets without panic=unwind support. +// To work around this problem, test is marked is should_panic, so it will +// be automagically skipped on unsuitable targets, such as +// wasm32-unknown-unkown. +// +// It means that we use panic for indicating success. +#[test] +#[should_panic(expected = "test succeeded")] +fn array_default_impl_avoids_leaks_on_panic() { + use core::sync::atomic::{AtomicUsize, Ordering::Relaxed}; + static COUNTER: AtomicUsize = AtomicUsize::new(0); + #[derive(Debug)] + struct Bomb(usize); + + impl Default for Bomb { + fn default() -> Bomb { + if COUNTER.load(Relaxed) == 3 { + panic!("bomb limit exceeded"); + } + + COUNTER.fetch_add(1, Relaxed); + Bomb(COUNTER.load(Relaxed)) + } + } + + impl Drop for Bomb { + fn drop(&mut self) { + COUNTER.fetch_sub(1, Relaxed); + } + } + + let res = std::panic::catch_unwind(|| <[Bomb; 5]>::default()); + let panic_msg = match res { + Ok(_) => unreachable!(), + Err(p) => p.downcast::<&'static str>().unwrap(), + }; + assert_eq!(*panic_msg, "bomb limit exceeded"); + // check that all bombs are successfully dropped + assert_eq!(COUNTER.load(Relaxed), 0); + panic!("test succeeded") +} + +#[test] +fn empty_array_is_always_default() { + struct DoesNotImplDefault; + + let _arr = <[DoesNotImplDefault; 0]>::default(); +}