Apparently the patch needed to fix this was the one Florian Weimer posted in november 2023, in "C compatibility issue in the configure script" <8734oqnlou....@gentoo.org> (if you don't have the mail history: https://lists.gnu.org/archive/html/bug-bash/2023-11/msg00104.html)
Maybe some compiler change triggered this now. -- Daniel lublin.se
