[buildd-tools-devel] Bug#595934: Bug#595934: sbuild: fails to install provided build-dependencies

[Roger Leigh]

On Tue, Sep 07, 2010 at 02:33:41PM +0200, Lucas Nussbaum wrote:
> sbuild breaks when trying to install build-dependencies that are
> provided by another package.
> Example building time 1.7-23:
> E: Package 'automaken' has no installation candidate
> automaken is a virtual package provided by: 
> Using  (no default, using first one)

sbuild doesn't support the use of virtual build dependencies
using the "internal" resolver.  It should do when using the
"aptitude" resolver, but this isn't currently used by the
buildds (except for experimental).

The internal resolver had limited (but broken) support for
hard-coded alternatives, but not package-provided alternatives.
I've recently ripped out the lot, since it was barely useful
and non-functional.

We can in theory implement virtual package resolving in the
internal resolver.  However, we would need to read and parse
the entire apt database, dumped with "apt-cache show '.*' or
equivalent.  I'd have to say, this will be both slow and not
a very productive use of our time to write, especially when
the aptitude resolver does this natively already.

If we do implement this, the main issue is which alternative
to pick when there are multiple choices.  The first one found,
first alphabetically, etc.?  Not sure what aptitude does, I
think apt-get just installs the first.


Regards,
Roger

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