diff --git a/src/liballoc/collections/linked_list.rs b/src/liballoc/collections/linked_list.rs index a0c9263673d74..6ee22834a460e 100644 --- a/src/liballoc/collections/linked_list.rs +++ b/src/liballoc/collections/linked_list.rs @@ -808,7 +808,21 @@ impl LinkedList { #[stable(feature = "rust1", since = "1.0.0")] unsafe impl<#[may_dangle] T> Drop for LinkedList { fn drop(&mut self) { - while let Some(_) = self.pop_front_node() {} + struct DropGuard<'a, T>(&'a mut LinkedList); + + impl<'a, T> Drop for DropGuard<'a, T> { + fn drop(&mut self) { + // Continue the same loop we do below. This only runs when a destructor has + // panicked. If another one panics this will abort. + while let Some(_) = self.0.pop_front_node() {} + } + } + + while let Some(node) = self.pop_front_node() { + let guard = DropGuard(self); + drop(node); + mem::forget(guard); + } } } diff --git a/src/liballoc/tests/linked_list.rs b/src/liballoc/tests/linked_list.rs index daa49c48c6a92..54a77d643cbe3 100644 --- a/src/liballoc/tests/linked_list.rs +++ b/src/liballoc/tests/linked_list.rs @@ -1,4 +1,5 @@ use std::collections::LinkedList; +use std::panic::catch_unwind; #[test] fn test_basic() { @@ -529,3 +530,109 @@ fn drain_filter_complex() { assert_eq!(list.into_iter().collect::>(), vec![1, 3, 5, 7, 9, 11, 13, 15, 17, 19]); } } + + +#[test] +fn test_drop() { + static mut DROPS: i32 = 0; + struct Elem; + impl Drop for Elem { + fn drop(&mut self) { + unsafe { + DROPS += 1; + } + } + } + + let mut ring = LinkedList::new(); + ring.push_back(Elem); + ring.push_front(Elem); + ring.push_back(Elem); + ring.push_front(Elem); + drop(ring); + + assert_eq!(unsafe { DROPS }, 4); +} + +#[test] +fn test_drop_with_pop() { + static mut DROPS: i32 = 0; + struct Elem; + impl Drop for Elem { + fn drop(&mut self) { + unsafe { + DROPS += 1; + } + } + } + + let mut ring = LinkedList::new(); + ring.push_back(Elem); + ring.push_front(Elem); + ring.push_back(Elem); + ring.push_front(Elem); + + drop(ring.pop_back()); + drop(ring.pop_front()); + assert_eq!(unsafe { DROPS }, 2); + + drop(ring); + assert_eq!(unsafe { DROPS }, 4); +} + +#[test] +fn test_drop_clear() { + static mut DROPS: i32 = 0; + struct Elem; + impl Drop for Elem { + fn drop(&mut self) { + unsafe { + DROPS += 1; + } + } + } + + let mut ring = LinkedList::new(); + ring.push_back(Elem); + ring.push_front(Elem); + ring.push_back(Elem); + ring.push_front(Elem); + ring.clear(); + assert_eq!(unsafe { DROPS }, 4); + + drop(ring); + assert_eq!(unsafe { DROPS }, 4); +} + +#[test] +fn test_drop_panic() { + static mut DROPS: i32 = 0; + + struct D(bool); + + impl Drop for D { + fn drop(&mut self) { + unsafe { + DROPS += 1; + } + + if self.0 { + panic!("panic in `drop`"); + } + } + } + + let mut q = LinkedList::new(); + q.push_back(D(false)); + q.push_back(D(false)); + q.push_back(D(false)); + q.push_back(D(false)); + q.push_back(D(false)); + q.push_front(D(false)); + q.push_front(D(false)); + q.push_front(D(true)); + + catch_unwind(move || drop(q)).ok(); + + assert_eq!(unsafe { DROPS }, 8); +}