On Sun, 20 Sep 2020, Warner Losh wrote:
0 is fine if sizeof(int) == sizeof(void *). Otherwise
varadic function
calls break.
I've never written anything that uses varargs, so I've never run into
that. But I've actually done quite a bit of work with an environment
where this isn't true: MS-DOS using the large or huge model. In this
environment, sizeof(int)=2, and sizeof(void*) is 4.
-uso.