https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100475
--- Comment #5 from Patrick Palka <ppalka at gcc dot gnu.org> --- (In reply to 康桓瑋 from comment #4) > (In reply to 康桓瑋 from comment #3) > > Also, the operator->() simply uses operator& instead of std::__addressof. > > > > https://godbolt.org/z/zfGnEoePG Good catch, thanks. > > Another issue is that the has_value() of this specialization will always > return true, which will make the precondition > __glibcxx_assert(_M_pred.has_value()) for filter_view's begin() almost > useless. That's fine I suppose, the assert will just be a no-op in that case. > > Although it is not clear why semiregular-box is partial specialization in > gcc-11, it is obvious that this needs to be treated with care. The advantage of the partial specialization is that it's space-optimal whereas the primary template is not, due to its use of std::optional.
