| // PR c++/67164 |
| // { dg-do compile { target c++11 } } |
| |
| #include <type_traits> |
| |
| namespace detail { |
| template <bool ...b> |
| struct fast_and |
| : std::is_same<fast_and<b...>, fast_and<(b, true)...>> |
| { }; |
| } |
| |
| template <typename ...Xn> |
| struct tuple { |
| tuple() { } |
| |
| template <typename ...Yn, typename = typename std::enable_if< |
| detail::fast_and<std::is_constructible<Xn, Yn&&>::value...>::value |
| >::type> |
| tuple(Yn&& ...yn) { } |
| |
| template <typename ...Yn, typename = typename std::enable_if< |
| detail::fast_and<std::is_constructible<Xn, Yn const&>::value...>::value |
| >::type> |
| tuple(tuple<Yn...> const& other) { } |
| }; |
| |
| tuple<tuple<>> t{}; |
| tuple<tuple<>> copy = t; |
