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range_common_reference_t
is missingSection: 26.2 [ranges.syn] Status: C++23 Submitter: Hewill Kang Opened: 2023-01-24 Last modified: 2023-11-22
Priority: Not Prioritized
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Discussion:
For the alias template iter_meow_t
in <iterator>
, there are almost all corresponding
range_meow_t
in <ranges>
, except for iter_common_reference_t
, which is used to
calculate the common reference type shared by reference
and value_type
of the iterator.
iter_const_reference_t
, and the latter has a corresponding sibling,
I think we should add a range_common_reference_t
for <ranges>
.
This increases the consistency of the two libraries and simplifies the text of getting common reference from a range.
Since C++23 brings proxy iterators and tuple
enhancements, I believe such introduction can bring some value.
[2023-02-06; Reflector poll]
Set status to Tentatively Ready after seven votes in favour during reflector poll.
[2023-02-13 Approved at February 2023 meeting in Issaquah. Status changed: Voting → WP.]
Proposed resolution:
This wording is relative to N4928.
Modify 26.2 [ranges.syn], header <ranges>
synopsis, as indicated:
#include <compare> // see 17.11.1 [compare.syn] #include <initializer_list> // see 17.10.2 [initializer.list.syn] #include <iterator> // see 25.2 [iterator.synopsis] namespace std::ranges { […] template<range R> using range_reference_t = iter_reference_t<iterator_t<R>>; // freestanding template<range R> using range_const_reference_t = iter_const_reference_t<iterator_t<R>>; // freestanding template<range R> using range_rvalue_reference_t = iter_rvalue_reference_t<iterator_t<R>>; // freestanding template<range R> using range_common_reference_t = iter_common_reference_t<iterator_t<R>>; // freestanding […] }