Revert r289727 due to PR31384 This patch reverts the changes to tuple which fixed construction from types derived from tuple. It breaks the code mentioned in llvm.org/PR31384. I'll follow this commit up with a test case. git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@289773 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/__tuple b/include/__tuple index 8e6d2bd..775d734 100644 --- a/include/__tuple +++ b/include/__tuple
@@ -453,57 +453,19 @@ #endif // _LIBCPP_HAS_NO_VARIADICS #ifndef _LIBCPP_CXX03_LANG +template <bool _IsTuple, class _SizeTrait, size_t _Expected> +struct __tuple_like_with_size_imp : false_type {}; -template <class _Tp, size_t _TSize, bool _Good = true> -struct __lookup_result { - using type = _Tp; - static constexpr bool _Success = _Good; - static constexpr size_t _Size = _TSize; -}; -using __lookup_failure = __lookup_result<void, (size_t)-1, false>; +template <class _SizeTrait, size_t _Expected> +struct __tuple_like_with_size_imp<true, _SizeTrait, _Expected> + : integral_constant<bool, _SizeTrait::value == _Expected> {}; -template <class ..._Args> -auto __deduce_tuple_type_ovl(tuple<_Args...>&) - -> __lookup_result<tuple<_Args...>, sizeof...(_Args)>; - -template <class _T1, class _T2> -auto __deduce_tuple_type_ovl(pair<_T1, _T2>&) - -> __lookup_result<pair<_T1, _T2>, 2>; - -template <class _Tp, size_t _Size> -auto __deduce_tuple_type_ovl(array<_Tp, _Size>&) - -> __lookup_result<array<_Tp, _Size>, _Size>; - -template <class _Tp> -auto __deduce_tuple_type_imp(int) - -> decltype(__deduce_tuple_type_ovl(_VSTD::declval<__uncvref_t<_Tp>&>())); -template <class> __lookup_failure __deduce_tuple_type_imp(...); - -// __deduce_tuple_like - Given a type determine if it is, or is derived from, -// a tuple-like type. This trait is used to support constructing and assigning -// to std::tuple from user-types derived from a tuple-like type. -template <class _TupleLike, - class _Result = decltype(__deduce_tuple_type_imp<_TupleLike>(0)), - bool _Good = _Result::_Success> -struct __deduce_tuple_like { - static_assert(_Good, "incorrect specialization choosen"); - static constexpr bool _Success = true; - static constexpr size_t _Size = _Result::_Size; - using _RawType = typename _Result::type; - using _QualType = - typename __propagate_value_category<_TupleLike>::template __apply<_RawType>; -}; - -template <class _TupleLike, class _Result> -struct __deduce_tuple_like<_TupleLike, _Result, /*_Good=*/false> { - static constexpr bool _Success = false; - static constexpr size_t _Size = (size_t)-1; -}; - -template <class _TupleLike, size_t _ExpectedSize, - class _Deduced = __deduce_tuple_like<_TupleLike>> -using __tuple_like_with_size = integral_constant<bool, - _Deduced::_Success && _Deduced::_Size == _ExpectedSize>; +template <class _Tuple, size_t _ExpectedSize, + class _RawTuple = typename __uncvref<_Tuple>::type> +using __tuple_like_with_size = __tuple_like_with_size_imp< + __tuple_like<_RawTuple>::value, + tuple_size<_RawTuple>, _ExpectedSize + >; struct _LIBCPP_TYPE_VIS __check_tuple_constructor_fail { template <class ...> 