Suppose there's a C language type _Any_func (with a <stdfunc.h> that has typedef _Any_func any_func;) that allows any func ptr type to be converted to _Any_func*, and back. (Like void* for functions.)

_Any_func* af = f;
printf("??", af);

?? is ...

0
0
0

If you have a fediverse account, you can quote this note from your own instance. Search https://pony.social/users/thephd/statuses/114463524862609381 on your instance and quote it. (Note that quoting is not supported in Mastodon.)