ok1(container_of(intp, struct foo, a) == &foo);
ok1(container_of(charp, struct foo, b) == &foo);
ok1(container_of_var(intp, &foo, a) == &foo);
ok1(container_of(intp, struct foo, a) == &foo);
ok1(container_of(charp, struct foo, b) == &foo);
ok1(container_of_var(intp, &foo, a) == &foo);