https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111499
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |12.5
Keywords| |missed-optimization
--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Adding a quick calls to size to operator<=> in bits/stl_vector.h fixes the
warning and we get just a return 0 for this code. This adds that the diff
end()-begin() for both __x and __y are known to be greater than equal to 0.
Like this:
template<typename _Tp, typename _Alloc>
[[nodiscard]]
constexpr __detail::__synth3way_t<_Tp>
operator<=>(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y)
{
(void)__x.size();
(void)__y.size();
return std::lexicographical_compare_three_way(__x.begin(), __x.end(),
__y.begin(), __y.end(),
__detail::__synth3way);
}
Since we know that in this case begin will always be before end. Though I
wonder if that knowledge should be pused down to
std::lexicographical_compare_three_way instead ...
