made better error message for <atomic>
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/tags/libcpp-16@128699 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/atomic b/include/atomic
index daf64b2..31385a2 100644
--- a/include/atomic
+++ b/include/atomic
@@ -530,6 +530,10 @@
_LIBCPP_BEGIN_NAMESPACE_STD
+#if !__has_feature(cxx_atomic)
+#error <atomic> is not implemented
+#else
+
typedef enum memory_order
{
memory_order_relaxed, memory_order_consume, memory_order_acquire,
@@ -1502,6 +1506,8 @@
#define ATOMIC_LONG_LOCK_FREE 0
#define ATOMIC_LLONG_LOCK_FREE 0
+#endif // !__has_feature(cxx_atomic)
+
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP_ATOMIC
