C 정적 다형성(CRTP)을 사용하여 유연한 반환 유형을 달성하고 컴파일 오류를 방지하려면 어떻게 해야 합니까?

template <typename derived_t>
class base {
public:
    typedef typename derived_t::value_type value_type;
};

template <typename T>
class derived : public base<derived<T>> {
public:
    typedef T value_type;
};

// Declare the base_traits class template
template <typename derived_t>
struct base_traits;

// Define the base class
template <typename derived_t>
struct base {
    typedef typename base_traits<derived_t>::value_type value_type;
};

// Define the derived class
template <typename T>
struct derived : public base<derived<T>> {
    typedef typename base_traits<derived<T>>::value_type value_type;
};

// Specialization of base_traits for derived
template <typename T>
struct base_traits<derived<T>> {
    typedef T value_type;
};