[Bug libstdc++/101599] New: ranges::__copy_or_move missing std::move for input_iterator

[hewillk at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101599

            Bug ID: 101599
           Summary: ranges::__copy_or_move missing std::move for
                    input_iterator
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hewillk at gmail dot com
  Target Milestone: ---

ranges_algobase.h#L247:

    else if constexpr (__is_normal_iterator<_Out>)
    {
      auto [__in,__out]
        = ranges::__copy_or_move<_IsMove>(__first, __last, __result.base());
      return {std::move(__in), decltype(__result){__out}};
    }

We should std::move __first to recursive ranges::__copy_or_move() call since
some input_iterator such as basic_istream_view​::​iterator does not have the
copy constructor.

#include <algorithm>
#include <ranges>
#include <sstream>

int main() {
  auto ints = std::istringstream{"42"};
  auto r = std::ranges::istream_view<int>(ints);
  std::vector v(1, 0);
  std::ranges::copy(r, v.begin());
}

https://godbolt.org/z/hh1o36df8