Section: 26.7.27.2 [range.adjacent.transform.view] Status: WP Submitter: Bo Persson Opened: 2023-06-17 Last modified: 2023-11-22 16:02:17 UTC
Priority: Not Prioritized
View all issues with WP status.
Discussion:
In section 26.7.27.2 [range.adjacent.transform.view] the class ranges::adjacent_transform_view got two new base() members from 3848.
The first one looks likeconstexpr V base() const & requires copy_constructible<InnerView> { return inner_.base(); }
Here the requirement is that InnerView is copy constructible, when it in fact returns an object of type V. That seems odd.
I would expect the constraint to instead be copy_constructible<V>.[2023-10-27; Reflector poll]
Set status to Tentatively Ready after five votes in favour during reflector poll.
[2023-11-11 Approved at November 2023 meeting in Kona. Status changed: Voting → WP.]
Proposed resolution:
This wording is relative to N4950.
Modify 26.7.27.2 [range.adjacent.transform.view], class template adjacent_transform_view synopsis, as indicated:
namespace std::ranges { template<forward_range V, move_constructible F, size_t N> requires view<V> && (N > 0) && is_object_v<F> && regular_invocable<F&, REPEAT(range_reference_t<V>, N)...> && can-reference<invoke_result_t<F&, REPEAT(range_reference_t<V>, N)...>> class adjacent_transform_view : public view_interface<adjacent_transform_view<V, F, N>> { […] adjacent_view<V, N> inner_; // exposition only using InnerView = adjacent_view<V, N>; // exposition only […] public: […] constexpr V base() const & requires copy_constructible<VInnerView> { return inner_.base(); } constexpr V base() && { return std::move(inner_).base(); } […] }; }