[libcxx-commits] [libcxx] [libc++] Use correct size for deallocation of arrays in shared_ptr (PR #68233)

[Ilya Biryukov via libcxx-commits]

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@@ -1137,7 +1137,8 @@ struct __unbounded_array_control_block<_Tp[], _Alloc> : __shared_weak_count
         __alloc_.~_Alloc();
         size_t __size = __unbounded_array_control_block::__bytes_for(__count_);
         _AlignedStorage* __storage = reinterpret_cast<_AlignedStorage*>(this);
-        allocator_traits<_StorageAlloc>::deallocate(__tmp, _PointerTraits::pointer_to(*__storage), __size);
+        allocator_traits<_StorageAlloc>::deallocate(
+            __tmp, _PointerTraits::pointer_to(*__storage), __size / sizeof(_AlignedStorage));
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ilya-biryukov wrote:

It actually seems to be more complicated.

The aligned storage has the size equal to the alignment of the control block (which is 8 bytes on my machine), so, e.g., we allocate and deallocate 5 elements of `AlignedStorage` for `int[]` when `__count_` is `0` (as the control block is 40 bytes on my machine).

In any case, I believe that reproducing exactly what gets passed to `allocate` is the right call here.

https://github.com/llvm/llvm-project/pull/68233