template <class T>
struct A
{
  ~A() = delete;
};

template <class T>
auto h() -> A<T>;
template <class T>
auto i(T) -> T;
template <class T>
auto f(T) -> decltype(i(h<T>()));
template <class T>
auto f(T) -> void;
auto g() -> void
{
  f(42);
}