Наследование шаблонных классов

#include <algorithm>
#include <vector>
#include <iostream>
#include <deque>
using namespace std;
 
// CLASS TEMPLATE queue
template <class _Ty, class _Container>
class Queue {
public:
    using value_type = typename _Container::value_type;
    using const_reference = typename _Container::const_reference;
  
    _NODISCARD bool empty() const noexcept(noexcept(c.empty())) /* strengthened */ {
        return c.empty();
    }
    _Container c{};
};
 
// CLASS TEMPLATE Priority_queue
template <class _Ty, class _Container, class _Pr = less<typename _Container::value_type>>
class Priority_queue: public Queue<_Ty, _Container> {
public:
    using value_type = typename _Container::value_type;
    using const_reference = typename _Container::const_reference;
          
    _NODISCARD bool empty() const noexcept(noexcept(c.empty())) /* strengthened */ {
        return c.empty();
    }
 
       _NODISCARD const_reference top() const noexcept(noexcept(c.front())) /* strengthened */ {
        return c.front();
    }
 
    void push(value_type&& _Val) {
        c.push_back(_STD move(_Val));
        _STD push_heap(c.begin(), c.end(), comp);
    }
 
    void pop() {
        _STD pop_heap(c.begin(), c.end(), comp);
        c.pop_back();
    }
    _Container c{};
     _Pr comp{};
};

 
    void pop() {
        _STD pop_heap(this->c.begin(), this->c.end(), comp);
        this->c.pop_back();
    }

using Queue<_Ty, _Container>::c;

using typename Queue<_Ty, _Container>::value_type;

     _NODISCARD auto top() const noexcept(noexcept(c.front())) /* strengthened */ {
        return c.front();
    }

#include <vector>
 
template <typename T>
struct A
{
    using value_type = T::value_type;
};
 
 
template <typename T>
struct B: A<T>
{
};
 
int main()
{
    B<std::vector<int>>::value_type n = 0;
}

152926856/source.cpp:6:24: error: need ‘typename’ before ‘T::value_type’ because ‘T’ is a dependent scope
     using value_type = T::value_type;
                        ^
152926856/source.cpp: In function ‘int main()’:
152926856/source.cpp:17:26: error: ‘value_type’ is not a member of ‘B<std::vector<int> >’
     B<std::vector<int>>::value_type n = 0;
                          ^~~~~~~~~~