rvalue reference or forwarding reference?

I know that for the following function

template <typename T>
void do_something(T&& arg);

the function parameter is a forwarding reference. But in the following case is it still a forwarding reference or an rvalue reference?

template <typename T>
class MyClass
{
    void do_something(T&& arg);
};

I think it is still a forwarding reference, but I'm not sure. Furthermore, I'd like to know what can be done to enforce an rvalue reference or a forwarding reference, if the result is not what I intended.