[libcxx-commits] [libcxx] [libc++] P2255R2: Add deleted tuple constructor overloads (PR #205379)

[Yihan Wang via libcxx-commits]

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@@ -616,21 +616,83 @@ public:
               _Not<_IsThisTuple<_Up...> >, // extension to allow mis-behaved user constructors
               is_constructible<_Tp, _Up>... > {};
 
-  template <class... _Up,
-            __enable_if_t< _And< _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>, _EnableUTypesCtor<_Up...> >::value,
-                           int> = 0>
+  template <class... _Up>
+  struct _EnableUTypesCtorBase : _And<_BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>, _EnableUTypesCtor<_Up...> > {};
+
+  template <bool, class... _Up>
+  struct _EnableUTypesCtorNoDangling : false_type {};
+
+#    if _LIBCPP_STD_VER >= 23
+  template <class... _Up>
+  static constexpr bool __has_danglings() {
+    if constexpr (sizeof...(_Up) == sizeof...(_Tp))
+      return (__reference_constructs_from_temporary_v<_Tp, _Up&&> || ...);
+    else
+      return false;
+  }
+
+  template <class _Source, class _DecayedSource = __remove_cvref_t<_Source> >
+  static inline constexpr bool __has_danglings_from_tuple_like = false;
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yronglin wrote:

Done.

https://github.com/llvm/llvm-project/pull/205379