Is there an easy way to tell if a class/struct has no data members?

Question

Hallo,

is there some easy way in C++ to tell (in compile-time) if a class/struct has no data members?

E.g. struct T{};

My first thought

Answer 1

Stepping on Konrad's answer, this handles classes with or without virtual functions.

template 
struct is_empty {
    struct empty_ { virtual ~empty_(); };
    struct helper_ : T { virtual ~helper_(); };
    static bool const EMPTY = sizeof(helper_) == sizeof(empty_);
};