Re: Bug#3085: bsdmainutils uses inappropriate `Conflicts bsdutils (<<...)'

[Ian Jackson <ian@chiark.chu.cam.ac.uk>]

David Engel writes ("Re: Bug#3085: bsdmainutils uses inappropriate `Conflicts bsdutils (<<...)'"):
...
> Ian, this is the type of situation where my conditional dependency
> idea could help.  I emailed it over a month ago but you never
> responded.  If you missed it or never received it, let me know and
> I'll resend it.

Thanks, I did receive it, and I've been giving it some thought.

The best I've come up with so far is a new control file field:
 Breaks: <package> [(<versionspec>)] [, ...]

This would cause dpkg to refuse to install if the package which would
be broken is also installed, unless --auto-deconfigure is enabled, in
which case it would deconfigure the package to be broken first.  (This
kind of thing is necessary so that dselect doesn't need to install all
the packages in some particular order.)

This is much the same effect as if the package being broken had said
 Depends: <package-being-installed> (<< <version-being-installed>)
or `Provides: <foo>' where the old version of the package being
installed provided foo but the new version doesn't.

How does this sound ?  Anyone else have any comments ?

(I won't implement this for the 1.1 release - I've just started a
`reorganisation freeze' for dpkg/dselect.  And in any case dpkg
doesn't at the moment quite handle correctly these kind of situations
where installing one package breaks some other packages'
dependencies.)

Ian.