Implement LWG Paper n3887: Consistent Metafunction Aliases. This adds std::tuple_element_t<> as an alias for tuple_element<>::type. Clean up the synopsis for tuple_element in <utility> as well.
llvm-svn: 202673
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 05c8dad23000f344763694d346e978ccaea07713
diff --git a/include/tuple b/include/tuple
index 30a958a..3a1752e 100644
--- a/include/tuple
+++ b/include/tuple
@@ -82,13 +82,15 @@
template <class... T> class tuple_size<tuple<T...>>;
template <intsize_t I, class T> class tuple_element; // undefined
template <intsize_t I, class... T> class tuple_element<I, tuple<T...>>;
+template <size_t _Ip, class ..._Tp>
+ using tuple_element_t = typename tuple_element <_Ip, _Tp...>::type; // C++14
// 20.4.1.5, element access:
template <intsize_t I, class... T>
typename tuple_element<I, tuple<T...>>::type&
get(tuple<T...>&) noexcept; // constexpr in C++14
template <intsize_t I, class... T>
- typename tuple_element<I, tuple<T...>>::type const&
+ typename const tuple_element<I, tuple<T...>>::type &
get(const tuple<T...>&) noexcept; // constexpr in C++14
template <intsize_t I, class... T>
typename tuple_element<I, tuple<T...>>::type&&
@@ -152,6 +154,11 @@
typedef typename tuple_element<_Ip, __tuple_types<_Tp...> >::type type;
};
+#if _LIBCPP_STD_VER > 11
+template <size_t _Ip, class ..._Tp>
+using tuple_element_t = typename tuple_element <_Ip, _Tp...>::type;
+#endif
+
// __tuple_leaf
template <size_t _Ip, class _Hp, bool=is_empty<_Hp>::value