Bug#946012: pyosmium unsatisfiable cross Build-Depends

[Helmut Grohne]

Control: tags -1 - moreinfo

Hi Bas,

On Tue, Dec 03, 2019 at 05:39:44AM +0100, Sebastiaan Couwenberg wrote:
> pyosmium is a leaf package, does it really matter that cannot be cross
> built?

It doesn't matter whether it is a leaf package or not. Whether it
matters is hard to know in advance.

> > I have less clue about shapely. I couldn't identify the actual use. Is
> > it really needed?
> 
> It's used in examples/amenity_list.py which is tested via
> test/test_examples.py.

Then it should also be annotated <!nocheck>. Thank you.

> > The attached patch implements the reductions for sphinx and mock. I used
> > reproducible builds and diffoscope to verify that these really are
> > correct. Please consider applying the patch and close this bug when
> > doing so.
> 
> I'll consider it, but it seems to not be worth the effort for this package.

The effort is already done. It's just a matter of applying the patch
now.

Do note that packages tend to become involved in dependency cycles
faster than one expects. Such reductions help breaking cycles before
they pop up. This particular patch is not specific to cross building and
helps with native bootstraps as well. It also lowers the build time on
buildds (by reducing the unpack time). I think it is a clear improvement
with little cost attached.

> What made you decide to work on this package?

Very often, it is the more complex and/or leaf packages that expose bugs
in the lower layers. I'm primarily after these, but report obvious
issues such as this as well. In general, I use popcon as a guide. Do
note that roughly every third Debian package is cross buildable today.
We're also making the whole archive build reproducibly even though you
might not see the benefit of doing so for pyosmium in particular.

Helmut