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

[Louis Dionne via libcxx-commits]

================
@@ -0,0 +1,38 @@
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+// REQUIRES: has-unix-headers
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+// UNSUPPORTED: libcpp-hardening-mode=none || libcpp-hardening-mode=fast
+// XFAIL: libcpp-hardening-mode=debug && availability-verbose_abort-missing
+
+// <atomic>
+
+// atomic_ref(T& obj);
+//
+// Preconditions: The referenced object is aligned to required_alignment.
+
+#include <atomic>
+
+#include "check_assertion.h"
+
+int main(int, char**) {
+  {
+    char c[8];
----------------
ldionne wrote:

```suggestion
    alignas(float) std::byte c[sizeof(float)];
```

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