Bug#545381: edos-builddebcheck: Always consider built-essential packages installable
On Thu, Nov 26, 2009 at 07:31:08PM +0100, Luk Claes wrote:
> Stefano Zacchiroli wrote:
> > On Thu, Nov 26, 2009 at 01:34:29PM +0100, Philipp Kern wrote:
> >> IIRC if you say, for instance, "apt-get install foo", then apt only considers
> >> the newest version (well, subjected to pinning, but let's consider that
> >> pinning is not present) and then tries to satisfy its dependencies. It does
> >> not notice that it's not installable *and then* retry with older versions.
> >
> > You're absolutely right: having played with more powerful dependency
> > solvers in the last months made me forget for a minute one of the most
> > annoying limitations of apt :-)
> >
> > So yes, given the specificities of the issue here, I thing we should add
> > a flag to edos-builddebcheck that made it ignore, directly during
> > parsing, the non-most-recent version of any package. I believe it should
> > not be the default, since edos-builddebcheck really answers the question
> > "are build-dep satisfiable?" and not "are build-dep satisfiable by
> > apt?". Of course wanna-build will pass that flag to edos-builddebcheck.
>
> Ignoring older packages is also not correct. If an Arch: any package
> with an older version has a strict dependency on an Arch: all package
> which is still available, apt will happily install them if you try to
> install the Arch:any package and will refuse to install the newer
> Arch:all package if you would try that AFAIK.
Indeed, edos-(build)debcheck would happily propose to install an
older version of a package to make an installation succeed. Anyway,
we will have to live with the fact that an analysis using
edos-builddebcheck will be an approximation of apt's behaviour since
apt has a build-in strategy that is, from a logical point of view,
incomplete. We can accept false positives (indicating buildability),
but must attempt to avoid false negatives. After Luk's argument that
means that edos-builddebbcheck should see the full list of packages.
-Ralf.
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