Try to fix Apple CI

Author: H-G-Hristov

libcxx/include/__type_traits/reference_constructs_from_temporary.h

@@ -18,10 +18,14 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
+#if __has_builtin(__reference_converts_from_temporary) ||                                                              \
+    (defined(_LIBCPP_COMPILER_CLANG_BASED) && (__clang_major__ >= 19) && (__clang_minor__ >= 1) &&                     \
+     (__clang_patchlevel__ >= 2))
+
 template <class _Tp, class _Up>
 const bool __reference_constructs_from_temporary_v = __reference_constructs_from_temporary(_Tp, _Up);
 
-#if _LIBCPP_STD_VER >= 23
+#  if _LIBCPP_STD_VER >= 23
 
 template <class _Tp, class _Up>
 struct _LIBCPP_TEMPLATE_VIS _LIBCPP_NO_SPECIALIZATIONS reference_constructs_from_temporary
@@ -31,6 +35,8 @@ template <class _Tp, class _Up>
 _LIBCPP_NO_SPECIALIZATIONS inline constexpr bool reference_constructs_from_temporary_v =
     __reference_constructs_from_temporary_v<_Tp, _Up>;
 
+#  endif
+
 #endif
 
 _LIBCPP_END_NAMESPACE_STD

libcxx/modules/std/type_traits.inc

@@ -107,7 +107,11 @@ export namespace std {
   using std::has_unique_object_representations;
 
 #if _LIBCPP_STD_VER >= 23
+#  if __has_builtin(__reference_constructs_from_temporary) ||                                                          \
+      (defined(_LIBCPP_COMPILER_CLANG_BASED) && (__clang_major__ >= 19) && (__clang_minor__ >= 1) &&                   \
+       (__clang_patchlevel__ >= 2))
   using std::reference_constructs_from_temporary;
+#  endif
 #  if __has_builtin(__reference_converts_from_temporary) ||                                                            \
       (defined(_LIBCPP_COMPILER_CLANG_BASED) && (__clang_major__ >= 19) && (__clang_minor__ >= 1) &&                   \
        (__clang_patchlevel__ >= 2))
@@ -291,7 +295,11 @@ export namespace std {
   using std::is_unsigned_v;
   using std::is_volatile_v;
 #if _LIBCPP_STD_VER >= 23
+#  if __has_builtin(__reference_constructs_from_temporary) ||                                                          \
+      (defined(_LIBCPP_COMPILER_CLANG_BASED) && (__clang_major__ >= 19) && (__clang_minor__ >= 1) &&                   \
+       (__clang_patchlevel__ >= 2))
   using std::reference_constructs_from_temporary_v;
+#  endif
 #  if __has_builtin(__reference_converts_from_temporary) ||                                                            \
       (defined(_LIBCPP_COMPILER_CLANG_BASED) && (__clang_major__ >= 19) && (__clang_minor__ >= 1) &&                   \
        (__clang_patchlevel__ >= 2))

libcxx/test/std/utilities/meta/meta.unary/meta.unary.prop/reference_constructs_from_temporary.pass.cpp

@@ -8,6 +8,9 @@
 
 // REQUIRES: std-at-least-c++23
 
+// These compilers don't support std::reference_converts_from_temporary yet.
+// UNSUPPORTED: apple-clang, clang-19.1.0, clang-19.1.1
+
 // <type_traits>
 
 // template<class T, class U> struct reference_constructs_from_temporary;