https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88085
--- Comment #19 from Petro Karashchenko <petro.karashchenko at gmail dot com> --- Sorry my bad again. Just checked with GCC 11 man page When used on a struct, or struct member, the aligned attribute can only increase the alignment; in order to decrease it, the packed attribute must be specified as well. When used as part of a typedef, the aligned attribute can both increase and decrease alignment, and specifying the packed attribute generates a warning.