| // PR c++/71117 |
| // { dg-do compile { target c++14 } } |
| |
| template <class T> T&& declval() noexcept; |
| template <class, class> |
| constexpr bool is_same = false; |
| template <class T> |
| constexpr bool is_same<T, T> = 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 rng) { |
| static_assert(is_same<decltype(rng), int>, ""); |
| return 42; |
| }; |
| indirected<decltype(f)> i(f); |
| static_assert(is_same<decltype(i(declval<int*>())), int>, ""); |
| } |