https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100044
Bug ID: 100044
Summary: ranges::subrange CTAD for __iterator_sentinel_pair not
work
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: hewillk at gmail dot com
Target Milestone: ---
libstdc++ defines the CATD of __iterator_sentinel_pair for the subranges in
ranges_util.h#L355:
355 template<__detail::__iterator_sentinel_pair _Pr>
356 subrange(_Pr)
357 -> subrange<tuple_element_t<0, _Pr>, tuple_element_t<1, _Pr>>;
358
359 template<__detail::__iterator_sentinel_pair _Pr>
360 subrange(_Pr, __detail::__make_unsigned_like_t<iter_difference_t<
361 tuple_element_t<0, _Pr>>>)
362 -> subrange<tuple_element_t<0, _Pr>, tuple_element_t<1, _Pr>,
363 subrange_kind::sized>;
It should be for the convenience to create a subrange directly from the
iterator and sentinel pair:
#include <ranges>
#include <vector>
int main() {
std::vector v1{1, 2, 3};
std::pair p{v1.begin(), v1.end()};
std::ranges::subrange sb{p};
}
But this seems to not work, since subrange(_Rng&& __r) will constraint the _Rng
at the beginning, which will cause us to be blocked early:
<source>: In function 'int main()':
<source>:7:29: error: no matching function for call to
'std::ranges::subrange<__gnu_cxx::__normal_iterator<int*, std::vector<int,
std::allocator<int> > >, __gnu_cxx::__normal_iterator<int*, std::vector<int,
std::allocator<int> > >,
std::ranges::subrange_kind::sized>::subrange(<brace-enclosed initializer
list>)'
7 | std::ranges::subrange sb{p};
Should we consider it a library bug?
