diff options
| -rw-r--r-- | libcxx/include/tuple | 4 | ||||
| -rw-r--r-- | libcxx/include/type_traits | 3 | ||||
| -rw-r--r-- | libcxx/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/default.pass.cpp | 17 |
3 files changed, 22 insertions, 2 deletions
diff --git a/libcxx/include/tuple b/libcxx/include/tuple index 93518d8bd64..21fa900ddc3 100644 --- a/libcxx/include/tuple +++ b/libcxx/include/tuple @@ -511,8 +511,8 @@ class _LIBCPP_TYPE_VIS_ONLY tuple typename tuple_element<_Jp, tuple<_Up...> >::type&& get(tuple<_Up...>&&) _NOEXCEPT; public: - template <bool _Dummy = true, class _Up = typename enable_if< - __all<(_Dummy && is_default_constructible<_Tp>::value)...>::value + template <bool _Dummy = true, class = typename enable_if< + __all<__dependent_type<is_default_constructible<_Tp>, _Dummy>::value...>::value >::type> _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR tuple() diff --git a/libcxx/include/type_traits b/libcxx/include/type_traits index 52fb5902485..1820bb2e4bc 100644 --- a/libcxx/include/type_traits +++ b/libcxx/include/type_traits @@ -216,6 +216,9 @@ template <class...> struct __void_t { typedef void type; }; #endif +template <class _Tp, bool> +struct _LIBCPP_TYPE_VIS_ONLY __dependent_type : public _Tp {}; + template <bool _Bp, class _If, class _Then> struct _LIBCPP_TYPE_VIS_ONLY conditional {typedef _If type;}; template <class _If, class _Then> diff --git a/libcxx/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/default.pass.cpp b/libcxx/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/default.pass.cpp index 8578d7fe91d..d282c9c68a4 100644 --- a/libcxx/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/default.pass.cpp +++ b/libcxx/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/default.pass.cpp @@ -35,6 +35,16 @@ struct ThrowingDefault { ThrowingDefault() { } }; +struct IllFormedDefault { + IllFormedDefault(int x) : value(x) {} + template <bool Pred = false> + constexpr IllFormedDefault() { + static_assert(Pred, + "The default constructor should not be instantiated"); + } + int value; +}; + int main() { { @@ -89,5 +99,12 @@ int main() assert(std::get<0>(t) == 0); assert(std::get<1>(t) == nullptr); } + { + // Check that the SFINAE on the default constructor is not evaluted when + // it isn't needed. If the default constructor is evaluted then this test + // should fail to compile. + IllFormedDefault v(0); + std::tuple<IllFormedDefault> t(v); + } #endif } |
