[libcxx-commits] [libcxx] [libc++] Deprecate the C++20 synchronization library before C++20 (PR #86410)

[Mark de Wever via libcxx-commits]

================
@@ -954,6 +954,14 @@ typedef __char32_t char32_t;
 #    define _LIBCPP_DEPRECATED_(m)
 #  endif
 
+#  if _LIBCPP_STD_VER < 20
+#    define _LIBCPP_DEPRECATED_ATOMIC_SYNC                                                                             \
+      _LIBCPP_DEPRECATED_("The C++20 synchronization library has been deprecated prior to C++20. Please update to "    \
+                          "using -std=c++20 if you need to use these facilities")
----------------
mordante wrote:

```suggestion
                          "using -std=c++20 if you need to use these facilities.")
```

https://github.com/llvm/llvm-project/pull/86410