aCC: warning 901: unknown option: `-0': use +help for online documentation.
I don't remember the last time I wrote anything that worked on HP-UX;
it's certainly not a platform I have any interest in supporting. I
mean, geez, next you'll be complaining that it doesn't work on VMS.
If you're going to deal with freakish systems like this, then yes,
you're going to have to go to the lowest-common-denominator. But
that's no reason why those of us not stuck in the 1980s should care.
For any feature you care to consider, ABSOLUTELY ANY FEATURE YOU HAVE
EVER USED, there exists a platform on which it does not work. That
does not mean you should not write any code.