This page is a snapshot from the LWG issues list, see the Library Active Issues List for more information and the meaning of C++23 status.

3590. split_view::base() const & is overconstrained

Section: 25.7.17.2 [range.split.view] Status: C++23 Submitter: Tim Song Opened: 2021-09-13 Last modified: 2023-11-22

Priority: Not Prioritized

View all issues with C++23 status.

Discussion:

Unlike every other range adaptor, split_view::base() const & is constrained on copyable instead of copy_constructible.

Since this function just performs a copy construction, there is no reason to require all of copyable — copy_constructible is sufficient.

[2021-09-24; Reflector poll]

Set status to Tentatively Ready after eight votes in favour during reflector poll.

[2021-10-14 Approved at October 2021 virtual plenary. Status changed: Voting → WP.]

Proposed resolution:

This wording is relative to N4892.

1. Modify 25.7.17.2 [range.split.view], class template split_view synopsis, as indicated:

   namespace std::ranges {
     template
       requires view && view &&
                indirectly_comparable, iterator_t, ranges::equal_to>
     class split_view : public view_interface> {
     private:
       […]
     public:
       […]
   
       constexpr V base() const& requires copyablecopy_constructible { return base_; }
       constexpr V base() && { return std::move(base_); }
   
       […]
     };