https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79319
--- Comment #3 from Marc Glisse <glisse at gcc dot gnu.org> --- It is a bit confusing indeed that vec4_t has sizeof: 16 and _Alignof: 32, one might expect an invariant that sizeof >= _Alignof... But just a typedef doesn't increase the size, while stuffing it in a struct/union does. And indeed if I try to make an array of vec4_t, I get the error: alignment of array elements is greater than element size. clang gives the same output on your program, and seems to ignore alignment if I make an array of vec4_t.
