How to secure CRTP against providing wrong superclass? [duplicate]

Answer 1

You can static_assert that the argument derives from Base<Argument>, but that's as far as you can go.

Answer 2

Make Base's destructor private, and then make Derived a friend of Base<Derived>:

template <class Derived>
class Base {
    private: ~Base() = default;
    friend Derived;
};

class Derived : public Base<Derived> {
};

This does not actually make doing

class AnotherDerived : public Base<Derived> {
};

illegal, but any attempt to actually construct an AnotherDerived will fail.