[Aptitude-devel] Bug#825707: aptitude: should not regard a package as removed when another package has a Provides on it

[Manuel A. Fernandez Montecelo]

Control: tags -1 + moreinfo


Hi,

2016-05-29 01:46 Vincent Lefevre:
>Package: aptitude
>Version: 0.8.1-1
>Severity: wishlist
>
>In the gnuplot5-data upgrade, one has:
>
>Package: gnuplot5-data
>Source: gnuplot5
>Version: 5.0.3+dfsg2-1
>Depends: aglfn, gnuplot-tex

I see a discrepancy in the data (as of today, maybe it changed since you
reported it).

The package which depends on gnuplot-text is "gnuplot-data", not
"gnuplot5-data".  "gnuplot5-data" does depend on aglfn, but not on
gnuplot-tex -- instead it *provides* the latter, as noted here:

>currently installed, and the new version has:
>
>Package: gnuplot5-data
>Source: gnuplot5
>Version: 5.0.3+dfsg2-2
>Replaces: gnuplot-tex
>Provides: gnuplot-tex
>Depends: aglfn
>Breaks: gnuplot-tex

I think that Provides, Breaks and Replaces together is wrong here (at
least in unversioned form, and I don't know if versioned work fully
yet), since the package conflicts with itself.

I am not sure why it does provide gnuplot-tex, since nothing except
"gnuplot-data" depends on it, and "gnuplot-data" and "gnuplot5-data"
probably shouldn't be install at the same time.


>Unfortunately, when I try an upgrade, gnuplot-tex is regarded as
>removed (the real package is removed, but due to the Provides,
>the package should still be regarded as being present).
>
>At least "aptitude safe-upgrade", "aptitude full-upgrade", and "U"
>in the UI are affected, i.e. aptitude proposes to keep gnuplot5-data
>as the default choice.
>
>Moreover, even with the solution where gnuplot-tex is removed,
>aptitude does not say that it is provided by gnuplot5-data, so
>that one has the impression that something is lost.

The description above is a bit vague.

If the only thing by why you deduce that aptitude considers
"gnuplot-text" removed is because the first proposal of aptitude is to
"keep" it, perhaps it's not because of the fact that it would be removed
but by the fact that it conflicts with itself, and in the face of a
conflict maybe the "Keep" solution given just scores higher than other
solutions.

If you saw it mentioned that it was removed in some specific screen or
console output, we will need the exact piece, because this information
is shown in many different places with many variants and nuances.


I haven't seen similar cases when packages depend on virtual packages
and are prevented to upgrade, if there's no other reason (e.g. other
packages depending with the version of the package providing the virtual
one), so I am inclined to thing that there is something particular about
this package / case.

Also, I was able to upgrade a few days ago this set without being given
any conflict related to the gnuplot packages, but maybe it's because of
other differences related to config options and installed packages /
versions between your system and mine.


Cheers.
-- 
Manuel A. Fernandez Montecelo <manuel.montezelo at gmail.com>