| // PR c++/71105 |
| // { dg-do compile { target c++14 } } |
| |
| template <typename T> T declval(); |
| template <typename, typename> struct is_same |
| { static constexpr bool value = false; }; |
| template <typename T> struct is_same<T, T> |
| { static constexpr bool value = true; }; |
| |
| template <class F> |
| struct indirected : F { |
| indirected(F f) : F(f) {} |
| template <class I> |
| auto operator()(I i) -> decltype(declval<F&>()(*i)) { |
| return static_cast<F&>(*this)(*i); |
| } |
| }; |
| |
| int main() { |
| auto f = [=](auto i) { return i + i; }; |
| auto i = indirected<decltype(f)>{f}; |
| static_assert(is_same<decltype(i(declval<int*>())), int>::value, ""); |
| } |