[libcxx-commits] [libcxx] [libc++][modules] Uses _LIBCPP_USING_IF_EXISTS. (PR #90409)

[Louis Dionne via libcxx-commits]

================
@@ -10,132 +10,132 @@
 export namespace std {
 
   // [atomics.order], order and consistency
-  using std::memory_order;
-  using std::memory_order_acq_rel;
-  using std::memory_order_acquire;
-  using std::memory_order_consume;
-  using std::memory_order_relaxed;
-  using std::memory_order_release;
-  using std::memory_order_seq_cst;
+  using std::memory_order _LIBCPP_USING_IF_EXISTS;
----------------
ldionne wrote:

I have no idea why we mark those with `_LIBCPP_USING_IF_EXISTS` in the headers. We shouldn't. However I suggest we blindly apply this patch to match the headers, and then fix the remaining issues in both the headers and the module file.

https://github.com/llvm/llvm-project/pull/90409