Bug#990305: Introduce ARC support in Perl cross-compiling for Debian

[Niko Tyni]

On Fri, Aug 27, 2021 at 11:30:48PM +0200, Helmut Grohne wrote:

> TL;DR: This is a kludge, not a solution.

Thanks for your reply. I certainly agree.

> On Fri, Aug 27, 2021 at 10:38:12PM +0300, Niko Tyni wrote:
> > I assume "tested in rebootstrap build" means the package builds, but
> > did anybody test the resulting packages?
> 
> I certainly did not. In particular, the main line of rebootstrap does
> not cross build perl.

I didn't mean to imply you should have tested it, apologies if it came
out that way. That part was mostly aimed at Evgeniy as the bug submitter.
 
> > I'm copying Helmut. Do you have any suggestions? Should I just take this
> > in and leave it to porters to worry about breakage?
> 
> I don't have an opinion here. Personally, I do not consider the way perl
> performs cross builds sustainable. That is the reason why rebootstrap
> still does not cross build perl to this date.

I don't consider it sustainable either, and I'd be surprised if anybody did.
It's a workaround to the lack of cross build support in Configure,
which still hasn't been fixed. I'm pessimistic of that ever happening.

The current hack of importing probe results from native builds has
a couple of upsides: it makes it possible to notice when other bits
of cross build support in the packaging rot away, and it gives us a
collection of probed values on different architectures with a history
of which bits change and which stay constant over releases.

But seeing that the hack is now over five years old and nothing has
changed does make me wonder if I should drop it altogether so that the
real issue would become more visible.

BTW I've also come across https://arsv.github.io/perl-cross/  which looks
interesting but hard to integrate cleanly in the Debian packaging.

> I still believe that the way to cross build perl is to make Configure
> (mostly) work for cross builds. The biggest step towards that has
> already been performed by generating Configure from source. Thank you. I
> believe that we can now rework it (and in part this has already happened
> upstream) to need less and less run tests. At some point, we'll reach a
> small and maintainable set of test results that does not have to be
> regenerated with every perl release.

I'm glad if you see progress here.

> > BTW, our development is currently targeting 5.34 so somebody needs to
> > port this. I'm not sure if there will be another 5.32 upload before
> > we get 5.34 in unstable.
> 
> That is why I find it unsustainable.
> 
> If you deem the effort for updating those files for arc ok, so be it.
> From my pov, it would be sufficient to start shipping them for arc once
> it becomes a ports architecture using the usual machinery.

Right. I don't intend to update any of those files manually myself. All
I currently do is run a script to extract them for the latest binary
builds on Debian buildds (including debian-ports).

For now, I'm leaning towards making a policy of only including config.sh
files from native package builds rather than possibly broken handcrafted
ones.
-- 
Niko