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Re: cdebconf, and a versioned dependency on debconf

On Tue, Dec 02, 2008 at 11:43:30AM -0200, Henrique de Moraes Holschuh wrote:
> On Fri, 28 Nov 2008, Manoj Srivastava wrote:
> >         Now, as of version 3.005, ucf started using a feaure that has
> >  long been a part of cdebconf, but was only ported to debconf in version
> >  1.5.19, so now ucf started depending on:
> >    debconf (>= 1.5.19) | cdebconf  
> >  and this is where trouble beings.

> >         Suppose a machine running stable has cdebconf installed. It also
> >  has an old version of debconf installed,  say, one that is older than
> >  1.5.19. Since cdebconf was installed, the dependency requirements are
> >  fully satisfied, so debconf was not updated.

> Wouldn't a Conflicts: debconf (< 1.5.19) work around the problem?

No, what that would do is break upgrades for half the Debian systems on the
planet by confusing apt into trying to remove ucf and everything that
depends on it.

> >         Now, in any situation where we have two alternatives, and have a
> >  versioned dependency on one of them, but do not actually control which
> >  of the alternatives gets used (if, say, they are drop in replacements),
> >  there is going to be a potential problem.

> When they don't conflict with each other?  Yes, it is broken.  In fact, it
> is the kind of stuff lintian should warn about, because it IS going to bite
> people hard, even if it doesn't happen everyday.

> One could maybe fix this in the packaging system itself, to add implicit
> conflicts on the complement version set for versioned Depends and
> Recommends.

> Anyway, unless the packaging system is updated to deal with it, it would be
> a good idea for lintian to warn on every dependency tree where an
> alternative is versioned, and the alternatives don't ALL conflict with each
> other.  Tricky, that one.

No.  That is not the bug.

Steve Langasek                   Give me a lever long enough and a Free OS
Debian Developer                   to set it on, and I can move the world.
Ubuntu Developer                                    http://www.debian.org/
slangasek@ubuntu.com                                     vorlon@debian.org

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