[Bug libstdc++/57272] node-based containers don't use allocator's pointer type internally

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57272

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |potswa at mac dot com

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
In PR55409#c15 David Krauss pointed out that ...

> the simplest case of a fancy pointer is a raw pointer to a class derived from value_type

I hadn't considered that case, and should ensure it works.

Currently I am working on something like this, which should handle it
correctly:

  template<typename _Traits,
           typename _Tp = typename _Traits::value_type,
           typename _Ptr = typename _Traits::pointer>
    struct _List_node_traits;

  // For C++03 allocators, and C++11 allocators without non-fancy pointers.
  template<typename _Traits, typename _Tp>
    struct _List_node_traits<_Traits, _Tp, _Tp*>
    {
      typedef _List_iterator<_Tp>       iterator;
      typedef _List_const_iterator<_Tp> const_iterator;
      typedef _List_node<_Tp>           _Node;
      typedef __detail::_List_node_base _Node_base;
      typedef _Node_base*               _Node_base_ptr;
      typedef const _Node_base*         _Node_base_const_ptr;
      typedef typename _Traits::template rebind<_Node>::other _Alloc_type;
      typedef __gnu_cxx::__alloc_traits<_Alloc_type> _Alloc_traits;
      ...
    };

#if __cplusplus >= 201103L
  // For C++11 allocators with fancy pointers.
  template<typename _Traits, typename _Tp, typename _Ptr>
    struct _List_node_traits
    {
      typedef typename _Traits::void_pointer    void_pointer;
      typedef _List_ptr_iterator<_Ptr>          iterator;
      typedef _List_ptr_const_iterator<_Ptr>    const_iterator;
      typedef _List_ptr_node<_Ptr>              _Node;
      typedef _List_ptr_node_base<void_pointer> _Node_base;
      typedef typename _Node_base::_SelfPtr     _Node_base_ptr;
      typedef typename _Node_base::_ConstSelfPtr        _Node_base_const_ptr;
      typedef typename _Traits::template rebind<_Node>::other _Alloc_type;
      typedef __gnu_cxx::__alloc_traits<_Alloc_type> _Alloc_traits;
      ...
    };
#endif