[libcxx-commits] [libcxx] [libc++] Implement C++20 atomic_ref (PR #76647)

[Damien L-G via libcxx-commits]

dalg24 wrote:

* Fixed the format (was using the wrong clang-format version...)
* Fixed some shadow warnings in the test
* Followed James' suggestion in https://github.com/llvm/llvm-project/pull/76647#issuecomment-1872988253 and dropped all the changes to `atomic_base_impl` and implemented `atomic_ref` directly in terms of the GCC `__atomic_*` builtins
* Haven't implemented `wait`, `notify_one`, nor `notify_all` yet

https://github.com/llvm/llvm-project/pull/76647