Tests/CompileFeatures/cxx_decltype_incomplete_return_types.cpp

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);
}