Re: using pkg-config modules from host (Re: wip/py-numpy + blas)

[Greg Troxel <gdt%lexort.com@localhost>]

At this point I'm really not sure what we should do.

A basic issue is that we have a "Linux" platform, but Linux isn't really
a platform.  <rms>It's only a kernel.</rms> It's really a family of
operating systems with different userlands.  And each member of that
family might or might not have various packages installed.   In a way
this is similar to platforms like NetBSD, where some library might be
present in 10 vs 9.  But the variability is much larger.

In general, in pkgsrc, we try to make the package behave the same -- and
have the same API/ABI -- regardless of which system it is built on.
When there are libraries that are sometimes native and sometimes not, we
bl3 them, using builtin.mk to find the native ones, so that users of the
package always get support.  Or we turn them off.

NIS is something that is perhaps not used that much, but it's part of
our computing heritage.   It's a fair question if it's time to drop it.
Or we could decide that it's ok to build it into python if present and
skip if not present.  So I can see

  1) make python always use nis
     a) fail if libs not present, so on Linux you need the packages
     b) create packages and bl3 them, with builtin.mk

  2) make python never use nis, by force-disabling

  3) allow python to be messy about nis
     a) try harder to have the 'is-nis-libs-present' tests match up with
        python
     b) don't worry about it, and anybody who can't build python can try
        to improve the tests

with comments

  1a doesn't seem reasonable

  1b is a lot of work

  2 withdraws functionality from all because of Linux complexity and is
  thus unreasonable

  3a is work and will help some people

  3b is where we are

Personally, I'm going down the 3b path as this is a problem I don't
have.

If somebody wants to do 1b or 3a that seems ok.  I am not ok with 2.
(When python withdraws nis, that's upstream, so whatever -- I don't
think we should fight upstreams normally.)