[gcc r13-3087] libstdc++: Guard use of new built-in with __has_builtin

[Jonathan Wakely <redi@gcc.gnu.org>]

https://gcc.gnu.org/g:dc70f3f81bb980b69a1910c2e6d3774ddd716846

commit r13-3087-gdc70f3f81bb980b69a1910c2e6d3774ddd716846
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Sep 29 11:30:05 2022 +0100

    libstdc++: Guard use of new built-in with __has_builtin
    
    Another case where I forgot that non-GCC compilers don't have this
    built-in yet.
    
    libstdc++-v3/ChangeLog:
    
            * include/bits/invoke.h (__invoke_r): Check
            __has_builtin(__reference_converts_from_temporary) before using
            built-in.

Diff:
---
 libstdc++-v3/include/bits/invoke.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libstdc++-v3/include/bits/invoke.h b/libstdc++-v3/include/bits/invoke.h
index 8724a764f73..8fa8cf876d8 100644
--- a/libstdc++-v3/include/bits/invoke.h
+++ b/libstdc++-v3/include/bits/invoke.h
@@ -130,8 +130,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     {
       using __result = __invoke_result<_Callable, _Args...>;
       using __type = typename __result::type;
+#if __has_builtin(__reference_converts_from_temporary)
       static_assert(!__reference_converts_from_temporary(_Res, __type),
 		    "INVOKE<R> must not create a dangling reference");
+#endif
       using __tag = typename __result::__invoke_type;
       return std::__invoke_impl<__type>(__tag{}, std::forward<_Callable>(__fn),
 					std::forward<_Args>(__args)...);