We've always taken a very conservative approach to portability with
Archiveopteryx. We run it ourselves under Linux and FreeBSD on x86 and
x86_64 systems, and those are the only platforms we've ever claimed to
support. Between the developers and our major users, we have access to
enough systems of that description that we can be reasonably confident
that the software will work without unpleasant surprises.
Beyond that, we've never been very ambitious. Once in a while, someone
would ask Does it work on NetBSD?
or Solaris or OS X. The
answer was usually yes, perhaps after a few (relatively minor) tweaks.
We would add #ifdefs and other portability patches to our
code only after someone suffered from an actual problem, never before.
If we couldn't (or didn't, regularly) test it, it wasn't supported.
This gloomy approach is in sharp contrast to the confidence encouraged
by autoconf. Had we used it, we could have saved a few users the trouble
of dealing with compile errors. We would have been testing our software
only on the few systems we did anyway (which happen to be the commonest
platforms in use), but autoconf would have helped us to feel
more portable. I don't want to think about what that would have done to
the number of
unreproducable
bugs we had to analyse; they were enough trouble as it was.
I was recently reminded of our curmudgeonly attitude in a conversation
with Hassath, who did a project on
FLOSS video editing software. One of her complaints was that it was
hard to find out not just what the hardware and software dependencies of
some program were, but also what configurations were known to
work. The documentation usually implied that any Linux system would work
fine, but in practice, people running a different distribution routinely
encountered problems that the developers had never seen and had no idea
how to address. This was the case even on her quite unremarkable Ubuntu
and amd64 test system, and she found it extremely frustrating.
Try as I might, I can't see optimism as a good approach to portability.