https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104262
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Why do you think it conforms to C11? "The value of alignment shall be a valid alignment supported by the implementation and the value of size shall be an integral multiple of alignment." If this is x86_64-linux, then it is aligned_alloc (8, 11); and 11 is not an integral multiple of 8.