https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107998
--- Comment #7 from James McKelvey <mckelvey at maskull dot com> --- That fix let the build proceed until it hit a #error much later. See 108011. Cygwin seems to be removing support for 32-bit, so although multilib has built for years, it won't anymore. That's my take. I'm not an expert on Cygwin or g++, I just build gcc-13 every snapshot and report bugs.