https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112783
--- Comment #12 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Note C26 (C2y) changes `memcpy(a, nullptr, 0)` into well defined from undefined. See C paper N3322 and PR 117023 which implements the change for it; basically it is undefined for previous C versions until then and only GCC 15+ implement the change for that but also requires a much newer glibc as glibc would mark the memcpy with nonnull rather than nonnull_if_nonzero attribute too.
