Re: Bug#148336: apt: problem solver wants to remove frozen-bubble
Wichert Akkerman <wichert@wiggy.net> writes:
> Ugh, ugly cc-list, list trim it.
>
> Previously Goswin Brederlow wrote:
> > So rare that we have "Replaces:" specially for the case of one package
> > replacing another. Is the problem solver ignoring that line?
>
> Replaces does not mean one packages replaces another, it merely means
> that a package has a file overlap.
Ok, I freshened up on debian policy:
----------------------------------------------------------------------
7.5.2 Replacing whole packages, forcing their removal
Secondly, Replaces allows the packaging system to resolve which
package should be removed when there is a conflict - see Conflicting
binary packages - Conflicts, Section 7.3. This usage only takes effect
when the two packages do conflict, so that the two usages of this
field do not interfere with each other.
In this situation, the package declared as being replaced can be a
virtual package, so for example, all mail transport agents (MTAs)
would have the following fields in their control files:
Provides: mail-transport-agent
Conflicts: mail-transport-agent
Replaces: mail-transport-agent
ensuring that only one MTA can be installed at any one time.
----------------------------------------------------------------------
frozen-bubble does not have a "Provides: frozen-bubble-lib" as in the
above example. But thats because theres no virtual package involved
here.
Following Policy frozen-bubble signals that it replaces
frozen-bubble-lib, the problem solver should react acordingly (Place
far less negative value on removing frozen-bubble-lib than on removing
frozen-bubble).
I'm still waiting for a real life example with similar dependencies
where the problemsolver would be right. If theres none it should be
changed to behave correctly. If there is some way of giving the
problem solver better hints should be though up.
MfG
Goswin
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