[libcxx-commits] [libcxx] [libc++] Use `__reference_constructs_from_temporary` if eligible (PR #141916)

[A. Jiang via libcxx-commits]

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@@ -310,7 +310,9 @@ class __tuple_leaf {
 
   template <class _Tp>
   static _LIBCPP_HIDE_FROM_ABI constexpr bool __can_bind_reference() {
-#    if __has_keyword(__reference_binds_to_temporary)
+#    if __has_builtin(__reference_constructs_from_temporary)
+    return !__reference_constructs_from_temporary(_Hp, _Tp);
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frederick-vs-ja wrote:

Do we want to use an internal type trait now?

Also, it seems that the `static_assert` on such problematic reference binding is totally non-Standard before C++23, and not strictly conforming even since C++23. Should we remove such checks, or backport the part of P2255R2 for `tuple` to old modes?

https://github.com/llvm/llvm-project/pull/141916