python3-numpy depending on *both* python 3.6 and 3.7

[Michael Hudson-Doyle]

On Sat, 25 Aug 2018 at 05:07, Steve Langasek <steve.langasek at ubuntu.com>
wrote:

> Hi Andreas,
>
> On Fri, Aug 24, 2018 at 10:05:23AM -0300, Andreas Hasenack wrote:
> > Hi,
> >
> > while investigating some DEP8 failures currently in cosmic's
> > migration, I came across this:
> > $ dpkg -s python3-numpy|grep Depends
> > Depends: python3 (<< 3.8), python3 (>= 3.6~), python3.6:any,
> > python3.7:any, python3:any (>= 3.3.2-2~), libblas3 | libblas.so.3,
> > libc6 (>= 2.27), liblapack3 | liblapack.so.3
> >
> > Is it ok/correct to depend on two python versions like that? Is the
> > point of it making sure numpy is available regardless which python 3
> > you are using? But at the cost of pulling in both?
> >
> > This is breaking python3-libcloud, which does not support python3.7,
> > when pulled in via fdroidserver:
> > https://pastebin.ubuntu.com/p/Kn77DXfxR5/
> >
> > The correct fix is to have python3-libcloud work with python 3.7, by
> > replacing "async" (a reserved keyword in python3.7) with something
> > else, like async_, but what caught my eye was this numpy dependency in
> > two python versions. And how libcloud ended up chosing 3.7 over 3.6
> > I'm not sure.
>
> This issue was reported in Debian during the previous python transition,
> and
> was closed without a permanent resolution:
>
>  https://bugs.debian.org/878281
>
> And a bug is now open again about the same issue wrt the python3.7
> transition:
>
>  https://bugs.debian.org/903663
>
> I agree that the current behavior is incorrect and not what we expect from
> packages that support multiple versions of python3.
>

So the problem is that python3-numpy contains a version of 'f2py' for each
supported version of Python. I guess the proper fix involves creating a
separate package for the each version of f2py? python3.6-f2py,
python3.7-f2py, and have python3-numpy depend on the one for the default
version of Python?

Cheers,
mwh
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