[gentoo-user] Simplify finding the package?

[Willie Wong]

Hi list, sorry for the nondescript title. Let me described what
happened. 

I ran `emerge --update --deep world' over the weekend which updated
app-text/poppler:

Sat Mar 12 22:00:46 2011 >>> app-text/poppler-0.16.3

Today I found out that a whole bunch of packages got broken, and so I
ran `revdep-rebuild -p'. To my surprise, revdep-rebuild wants to
downgrade to app-text/poppler-0.14.5. That's odd, I thought. 

So I ran `emerge --pretend --oneshot --verbose --tree' against the
list of packages produced by revdep-rebuild, and it displays near the
bottom that poppler-0.14.5 is a dependency of luatex-0.65 which is a
dependency of texlive-core-2010-r1. Okay. So I thought that one of
those two packages have an explicit dependency on a lower version of
poppler. And I thought I want to file a bug about that. 

Digging into the ebuilds for luatex and texlive, I can't find any
reason why they would require poppler-0.14.5, and not 0.16.3. So after
puzzling about it for 20 minutes, I did the stupid thing, and tried

`emerge --oneshot --pretend luatex texlive-core'

and lo-and-behold, the poppler dependency does not appear!

Then combing through the list of packages one-by-one, I finally found
(on the second-to-last package that I tried) that the culprit is
in fact python-poppler. 

------------------------------------

Now, two questions:

  (a) Should this be considered a bug in portage? The presented
information from `emerge --pretend --tree' is misleading to which
package is actually causing the downgrade request. 
  (b) Is there a way to have found that python-poppler was the culprit
without running `emerge --pretend' on each of the list of 16 packages? 

Thanks, 

W
-- 
Willie W. Wong                                     wwong@××××××××××××××.edu
Data aequatione quotcunque fluentes quantitae involvente fluxiones invenire 
         et vice versa   ~~~  I. Newton