关于#STL#的问题，如何解决？(标签-学习)

我最近在学习STL，找了个项目在尝试跟着写，然后项目里的iterator_traits和STL源码剖析的不太一样。然后写List容器时遇到了一些我无法解决的错误

问题相关代码，请勿粘贴截图

//源码剖析的写法
template<typename Iterator>
struct iterator_traits
{
    typedef typename    Iterator::iterator_category        iterator_category;
    typedef    typename    Iterator::value_type            value_type;
    typedef    typename    Iterator::difference_type        difference_type;        //表示容器的最大容量
    typedef    typename    Iterator::pointer                pointer;
    typedef    typename    Iterator::reference                reference;
};
//找的项目的写法
template <class T>
struct has_iterator_cat
{
private:
  struct two { char a; char b; };
  template <class U> static two test(...);  //...省略参数
  template <class U> static char test(typename U::iterator_category* = 0);
public:
  static const bool value = sizeof(test(0)) == sizeof(char);
};

template <class Iterator, bool>
struct iterator_traits_impl {};

template <class Iterator>
struct iterator_traits_impltrue>         //偏特化版本
{
  typedef typename Iterator::iterator_category iterator_category;
  typedef typename Iterator::value_type        value_type;
  typedef typename Iterator::pointer           pointer;
  typedef typename Iterator::reference         reference;
  typedef typename Iterator::difference_type   difference_type;
};

template <class Iterator, bool>
struct iterator_traits_helper {};

template <class Iterator>
struct iterator_traits_helpertrue>
  : public iterator_traits_impltypename Iterator::iterator_category, input_iterator_tag>::value ||
  std::is_convertible<typename Iterator::iterator_category, output_iterator_tag>::value>          
{
};

//出错的函数
template<typename T>
    template<typename Iter>
    inline void List::copy_init(Iter first, Iter last)
    {
        node_ = base_allocator::allocate(1);
        node_->unlink();
        size_type n=mystl::distance(first, last);    //只要有这个距离函数就会报错
        size_ = n;
        try
        {
            for (; n > 0; --n, ++first)
            {
                auto node = create_node(1);        
                link_nodes_at_back(node->as_base(), node->as_base());
            }
        }
        catch (...)
        {
            clear();
            base_allocator::deallocate(node_);    
            node_ = nullptr;
            throw;
        }
    }

运行结果及报错内容

我按照源码剖析的写法，size_type n=mystl::distance(first, last); 使用这个函数时就会报错如下

错误全部指向我按照源码剖析写的iterator_traits。
想不明白这是为什么？我在vector容器中也是用了这个计算迭代器距离的函数，就没有问题