Proposed resolution:

This wording is relative to N4659.

1. Change [iterator.traits] as indicated:

   -3- It is specialized for pointers as

   namespace std {
     template<class T> struct iterator_traits<T*> {
       using difference_type = ptrdiff_t;
       using value_type = T;
       using pointer = T*;
       using reference = T&;
       using iterator_category = random_access_iterator_tag;
     };
   }
   

   and for pointers to const as

   namespace std {
     template<class T> struct iterator_traits<const T*> {
       using difference_type = ptrdiff_t;
       using value_type = T;
       using pointer = const T*;
       using reference = const T&;
       using iterator_category = random_access_iterator_tag;
     };
   }
   

   -?- These partial specializations for pointers apply only when T is an object type.

[ 2019-02; Kona Wednesday night issue processing ]

This was resolved by the adoption of P0896 in San Diego.

[ 2017-07 Toronto Wed Issue Prioritization ]

Priority 3; Billy to look into arrays of unknown bounds

A customer recently triggered an unexpected SFINAE condition with class path. We constrain the constructor that takes const Source& by asking if iterator_traits<Source>::value_type is one that's OK. This forms iterator_traits<void*>, which is a hard error, as it tries to form void&.

Pointers-to-non-object-type can never act as iterators, as they don't support pointer arithmetic (as we recently discovered in atomic<void*> / atomic<int(*)(int)>).