https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109700
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- It is replacing __builtin_alloca with __builtin_alloca_with_align . __builtin_alloca is NOT known not to throw with the definition provided and that is the cause of the issue. Adding [[gnu::nothrow]] fixes the issue.