https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126675
--- Comment #3 from Marco Rubini <marco.rubini08 at gmail dot com> --- libstdc++ already exports __do_vformat_to as an external symbol, so it would be a breakage to drop it in a future version. I don't know if it was intended or not, but given that it is already exported, I think it would just be better to have an explicit external declaration for it in <format>.
