Bug#752989: libio-callback-perl: FTBFS with Perl 5.20: alternative dependencies

[Niko Tyni]

On Sat, Jun 28, 2014 at 03:31:29PM +0200, Jonas Smedegaard wrote:

> I don't understand.  Do you not find it relevant for perl modules to 
> declare to declare dependencies and build-dependencies 
> deterministically, or do you find that this particular use of "|" does 
> not affect determinism?

The latter. When perl or perl-modules provides a virtual package, it
will always be installed on the build system as perl+perl-modules are
transitively build essential (at least via dpkg-dev -> libdpkg-perl).
Thus there's no need to make an undeterministic choice.

I can see that there's a chance that this might not be the case at some
point in the future. I expect that perl would be very hard to disentangle
from the build-essential set in practice, and we may end up declaring
it explicitly build-essential anyway.

In the specific case of libmodule-build-perl discussed here, that's not
even a theoretical possibility: at this point, I think we can be certain
that perl-modules will not fall out of the build essential set before
libmodule-build-perl stops being a virtual package.

In general, I dislike the idea that "unguarded" unversioned dependencies
on a virtual package provided by the perl package are somehow wrong.
But I suppose the future proofness is an argument for adding the guards,
even if I don't think it's worth the bother.
-- 
Niko Tyni   ntyni at debian.org