3377. elements_view::iterator befriends a specialization of itself

Section: 25.7.23.3 [range.elements.iterator] Status: C++20 Submitter: Casey Carter Opened: 2020-01-18 Last modified: 2021-02-25

Priority: 0

View other active issues in [range.elements.iterator].

View all other issues in [range.elements.iterator].

View all issues with C++20 status.

Discussion:

The synopsis of the exposition-only class template elements_view::iterator in 25.7.23.3 [range.elements.iterator] includes the declaration "friend iterator<!Const>;". We typically don't depict such friend relationships in the Library specification, leaving the choice of how to implement access to private data from external sources to implementer magic. For consistency, we should strike this occurrence from elements_view::iterator.

[2020-02-08 Status set to Tentatively Ready after ten positive votes on the reflector.]

Proposed resolution:

This wording is relative to N4842.

1. Modify 25.7.23.3 [range.elements.iterator], class template elements_view::iterator synopsis, as indicated:

   namespace std::ranges {
     template<class V, size_t N>
     template<bool Const>
     class elements_view<V, N>::iterator { // exposition only
       using base_t = conditional_t<Const, const V, V>;
       friend iterator<!Const>;
   
       iterator_t<base_t> current_;
     public:
       […]
     };
     […]
   }