[libcxx-commits] [libcxx] [libc++] Implement P0718R2: `atomic<shared_ptr<T>>` (PR #78317)

[A. Jiang via libcxx-commits]

frederick-vs-ja wrote:

> This is quite a "dumb" implementation: It just reuses the now-deprecated functions in [[depr.util.smartptr.shared.atomic]](https://wg21.link/depr.util.smartptr.shared.atomic) on a held `std::{shared/weak}_ptr<T>` member.

These functions are removed in C++26 ([P2869R3](https://wg21.link/p2869r3)), however, such strategy would make them not removable in libc++.

https://github.com/llvm/llvm-project/pull/78317