https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110917
--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jonathan Wakely <r...@gcc.gnu.org>: https://gcc.gnu.org/g:c5ea5aecac323e9094e4dc967f54090cb244bc6a commit r14-3068-gc5ea5aecac323e9094e4dc967f54090cb244bc6a Author: Jonathan Wakely <jwak...@redhat.com> Date: Mon Aug 7 14:37:25 2023 +0100 libstdc++: Constrain __format::_Iter_sink for contiguous iterators [PR110917] We can't write to a span<_CharT> if the contiguous iterator has a value type that isn't _CharT. libstdc++-v3/ChangeLog: PR libstdc++/110917 * include/std/format (__format::_Iter_sink<CharT, OutIter>): Constrain partial specialization for contiguous iterators to require the value type to be CharT. * testsuite/std/format/functions/format_to.cc: New test.