#include #include #include template struct innermost_impl { using type = T; }; template class E, typename Head, typename... Tail> struct innermost_impl> { using type = typename innermost_impl::type; }; template using innermost = typename innermost_impl::type; template struct X; static_assert(std::is_same>>>, int>::value, ""); static_assert(std::is_same>>>, int>::value, ""); int main() { }