Proposed resolution:

Change [conversions.string]:

template<class Codecvt, class Elem = wchar_t,
         class Wide_alloc = std::allocator<Elem>,
         class Byte_alloc = std::allocator<char> > class wstring_convert {
  public:
    typedef std::basic_string<char, char_traits<char>, Byte_alloc> byte_string;
    typedef std::basic_string<Elem, char_traits<Elem>, Wide_alloc> wide_string;
     ...

Change [conversions.string], p3:

-3- The class template describes an ob ject that controls conversions between wide string ob jects of class std::basic_string<Elem, char_traits<Elem>, Wide_alloc> and byte string objects of class std::basic_string<char, char_traits<char>, Byte_alloc> (also known as std::string).