Bug#878326: cups FTCBFS: runs host architecture utilities during build again

[Helmut Grohne <helmut@subdivi.de>]

Hi Didier,

On Fri, Oct 13, 2017 at 10:31:50AM +0200, Didier 'OdyX' Raboud wrote:
> Thanks for your scrutiny and your patch. Is there a "Cross-Builds Status" page 
> I could monitor myself to proactively detect these ?

Wow. That was quick. :)

Presently, there is no such page. A number of people (including Matthias
Klose and Hector Oron) have requested such a page, but I have not
invested time and computing resources into generating such a thing at
this time, because I am not convinced of its value.

I see two potential user groups for such a page:

 * People interested in cross building and fixing packages. I haven't
   seen any other people sending patches. So this group likely doesn't
   exist. If it did, picking a random package would be a good way to
   find broken ones as 90% of Debian fails to cross build. In any case,
   the page would be unnecessary.

 * Maintainers (like you) checking cross build status. I expect that
   such maintainer look into tracker.d.o. A very annoying problem with
   cross building is missing or wrong Multi-Arch annotations. Thus I set
   out to help maintainers and started feeding "multiarch hints"[1] into
   tracker.do. About 10000 hints are being generated since about half a
   year ago. Yes, I am generating hints for 1 in 6 binary packages.
   Sadly, the number of hints hasn't gone down, but up. This suggests
   that there are *very* few maintainers that check tracker.d.o. Given
   that multiarch hints are trivial to fix with little effort and that
   cross build issues are much harder, I don't expect anyone to care
   about cross build failures. For comparison, roughly 2/3 cross build
   bugs with patches get applied by maintainers.

Thus, I am convinced that creating a cross build status page is not
worth my effort. I don't expect anyone to consume the output. I hope you
can understand that reasoning.

I'd be very happy to be wrong about this.

If someone sends cross build patches or multiarch hints start getting
adopted. I'm going to revisit this.

What you can do at any time though, is testing cross building for
yourself. I'm sure that you have either sbuild or pbuilder set up. For
sbuild, you pass[2]:

    --host=arm64 --add-depends="libc-dev, libstdc++-dev"

and for pbuilder you pass:

    --host-arch=arm64

Helmut

[1] https://wiki.debian.org/MultiArch/Hints
[2] The --add-depends is there to work around #815172, but pbuilder has
    the workaround built in. The proper fix of that bug is non-trivial.