[Bug libstdc++/119415] flat_set::insert_range may not handle C++20 common-range

[tkaminsk at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119415

--- Comment #12 from Tomasz Kamiński <tkaminsk at gcc dot gnu.org> ---
I have realized that with the resolution of the
https://cplusplus.github.io/LWG/lwg-defects.html#3749, you can run into this
problem by doing:

auto r = std::views::iota(__int128(0)) | std::views::take(5) |
std::views::common;
s.insert_range(r);

The GCC does not yet implement this issue
(https://gcc.gnu.org/wiki/LibstdcxxTodo), but checking for
iterator_traits<It>::iterator_category being derived from input_iterator_tag as
you suggested will avoid the issue.