[Solved?] Re: How do I clear no-longer-usable packages from poudriere?

Well... I had managed to get myself confused.  In fairness, some of the
clues I was getting were misleading (at best).

TL;DR: After rebuilding a few packages, re-installing them, finding
that that didn't help, then force-re-installing the most recently-built
package for dns/libidn (libidn-1.38_1; package built 24 January),
ghostscript stopped whining and printing started working again.

The clue to try that came when I figured I would try to bypass cups, and
just feed a Postscript file to lpd.  I happened to have a bunch of PDFs
around, so I tried:

albert(14.0-S)[14] pdf2ps pdf/bike.pdf >/tmp/bike.ps
ld-elf.so.1: /usr/local/lib/libidn.so.12: version LIBIDN_1.0 required by /usr/local/lib/libgs.so.10 not defined

Oh.

So I forced a rebuild & re-install of print/ghostscript10 (after
determining that /usr/local/lib/libgs.so.10 is provided by that
package).  Tried `pdf2ps` again; same failure.

Tried a few other packages (including print/cups) that got rebuilt when
I told poudriere to just rebuild print/ghostscript10).  Same failure.

Noted that /usr/local/lib/libidn.so.12 comes from dns/libidn, so I
forced a re-install of that... and that instantiation of the issue
appears to be resolved.

Now, given that this type of failure can occur:
* I know how to check for missing libraries.  How can I (similarly)
  check for an executable or library that needs some symbol or version
  that "is not defined"?

  I managed to "get lucky" and trigger something that actually
  provided a reasonably clear error message -- this time.  Until I
  did that, I could (sometimes) see that a print job failed to print
  because the "filter failed."  But since last week, it was named that
  was failing (for me), it's obvious that this mode of failure could
  affect any (dynamically-linked?) executable (or libraries that
  it uses), yeah?

* Is there a way to prevent the problem from occurring?

* Now that the problem has definitely occurred, is there a way to
  detect that a (poudriere-built) package suffers from that problem?


That said, >8 years of weekly updates without a "hiccup" worth
mentioning is a pretty good record. :-)


Peace,
david
-- 
David H. Wolfskill                              david@catwhisker.org
Alexey Navalny was a courageous man; Putin has made him a martyr.

See https://www.catwhisker.org/~david/publickey.gpg for my public key.