mirror of https://github.com/rust-lang/rust
49 lines
1.8 KiB
Rust
49 lines
1.8 KiB
Rust
#![feature(alloc_error_hook, allocator_api)]
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use std::alloc::{set_alloc_error_hook, AllocError, Allocator, Layout, System};
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use std::collections::VecDeque;
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use std::panic::{catch_unwind, AssertUnwindSafe};
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use std::ptr::NonNull;
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#[test]
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#[cfg_attr(not(panic = "unwind"), ignore = "test requires unwinding support")]
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fn test_shrink_to_unwind() {
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// This tests that `shrink_to` leaves the deque in a consistent state when
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// the call to `RawVec::shrink_to_fit` unwinds. The code is adapted from #123369
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// but changed to hopefully not have any UB even if the test fails.
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struct BadAlloc;
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unsafe impl Allocator for BadAlloc {
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fn allocate(&self, l: Layout) -> Result<NonNull<[u8]>, AllocError> {
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// We allocate zeroed here so that the whole buffer of the deque
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// is always initialized. That way, even if the deque is left in
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// an inconsistent state, no uninitialized memory should be accessed.
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System.allocate_zeroed(l)
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}
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unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout) {
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unsafe { System.deallocate(ptr, layout) }
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}
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unsafe fn shrink(
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&self,
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_ptr: NonNull<u8>,
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_old_layout: Layout,
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_new_layout: Layout,
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) -> Result<NonNull<[u8]>, AllocError> {
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Err(AllocError)
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}
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}
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set_alloc_error_hook(|_| panic!("alloc error"));
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let mut v = VecDeque::with_capacity_in(15, BadAlloc);
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v.push_back(1);
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v.push_front(2);
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// This should unwind because it calls `BadAlloc::shrink` and then `handle_alloc_error` which unwinds.
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assert!(catch_unwind(AssertUnwindSafe(|| v.shrink_to_fit())).is_err());
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// This should only pass if the deque is left in a consistent state.
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assert_eq!(v, [2, 1]);
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}
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