R devel - Sep 2018 - How do I prevent macOS from attempting to build my package?

[ Initially posted in r-package-devel, now reposting here by request from
  Uwe; my apologies for the cross-post. ]

Package status reports come in three different severities: NOTE, WARNING, and
ERROR. Motivated by Brodie's nice (dependency-free) accessor function for
per-maintainer status [1],  I have looked into reducing the number of ERRORs.

I hit a road block. Several of my packages depend on external libraries that
must be present. I test for these in configure, but their absence is still an
ERROR.  This makes the situation on macOS a little delicate. Simon, who is
doing, and always done, a metric ton of work around R and OS X / maxOS is the
only one who could change this but I cannot realistically ask him to keep a
number of (in some cases more difficult or esoteric) libraries afloat. And
some of these have now been missing on his platform for several years.

And in one case (RcppAPT, requiring libapt-dev) the build is even
imppossible.  Now, the Fedora maintainer knows this and has the build
blacklisted.

Hence:

  R> source("checkCRAN.R")                            
                 Package ERROR WARN NOTE OK
  [...]
  23             RcppAPT     2            4
  [...]

No failures from Fedora.  But two from macOS which I can never ever get rid
off (unless I do silly code acrobatics by #ifdef'ing all real code away).

So here is my question:  Can we we please refine

  OS_type: unix

a little more, and/or maybe allow other blacklists in the package upload?

Thoughts or comments most welcome.

Thanks,  Dirk



[1]
https://gist.github.com/brodieG/e60c94d4036f45018530ea504258bcf3#file-cran-check-r

-- 
http://dirk.eddelbuettel.com | @eddelbuettel | edd at debian.org