[Aptitude-devel] Bug#823928: aptitude wants to remove manually installed packages with SolutionCost "safety, removals"

[Manuel A. Fernandez Montecelo]

2016-05-17 3:15 GMT+01:00 Vincent Lefevre <vincent at vinc17.net>:
>> This is not the case, but it might happen that it
>> could upgrade by removing some packages (which maybe are not interesting
>> for the user or forgot that they were installed), or upgrading some
>> packages to a suite like experimental (which is a "non-default/safety
>> action", but which some people request from time to time, e.g. #608811),
>> or that one doesn't really want to use these multi-arch packages
>> anymore.
>
> But note that I use SolutionCost "safety, removals", so that it should
> avoid packages from experimental or remove packages.

aptitude never did that... and never will.

It merely suggests those kind of suggestions later than other less
dangerous ones, if it finds those before within a reasonable amount of
time, while exploring the graph of solutions.


>> So the upgrade cannot happen until all packages are at the same exact
>> version, including binNMUs, without removing some of them.
>
> This is not specific to multi-arch. This can also happen with usual
> dependencies. But since I use SolutionCost "safety, removals", I
> prefer to block the upgrade of the problematic packages.

I was explaining the situation that you submitted in this bug report,
which is indeed due to multi-arch skew.

There is no point in discussing hypothetical cases.


>> 2016-05-10 15:29 Vincent Lefevre:
>> > In the UI, I get the same behavior as with --full-resolver:
>> > aptitude wants to remove packages. And in both cases, if I
>> > look at the next solutions, aptitude wants to remove more
>> > and more packages.
>>
>> I hope that one of the solutions offered is to "Keep all at the current
>> version"?
>
> No, the next solutions were worse, i.e. more packages would have been
> removed.

You can surely guide the resolver to a solution that amounts to not
upgrade any package.


> Note also that before I reported the bug, there were more packages
> proposed for upgrade, but because any solution wanted to remove
> packages, I had to select the upgradable packages (those with no
> conflicts) one by one to upgrade them. Very annoying!

aptitude cannot magically resolve problems when the packages/versions
involved are incompatible, so I am not sure why you think that it's a
problem caused by aptitude, but it isn't.


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