[Buildroot] [PATCH 3/5] python-cffi: add host variant

[Yann E. MORIN <yann.morin.1998@free.fr>]

Thomas, Yegor, All,

On 2015-12-25 20:00 +0100, Thomas Petazzoni spake thusly:
> On Thu, 24 Dec 2015 23:12:49 +0100, Yegor Yefremov wrote:
> > Target variant doesn't need pycparser. cffi's setup.py seems to
> > distinguish, if we install real package or cross-compiled one:
> > 
> >         install_requires=[
> >             'pycparser',
> >         ] if cpython else [],
> 
> I don't understand how this "if cpython" is relevant to make the
> different between the native (host) variant or the cross-compiled
> (target) variant. cpython is defined as is:
> 
>     cpython = ('_cffi_backend' not in sys.builtin_module_names)
> 
> Can you give some more details?

Yegor and I briefly discussed this on IRC yesterday, but I'm not really
convinced by this reply either. I forgot to reply yesterday...

What I understand, however, is that they want to differentiate between
cpython (the 'ofiicial' native Python interpreter), and PyPy (the Python
interpreter written in Python).

Of course, I don't see how this all works. It seems in
cross-compilation. there differentiation criterai beliveves it is
running under PyPy amd thus they do not need pycparser.

But thtat's just incorrect, because we may have a host-python with
cffi_backend at one point, and thus the check above will eventually
differentiate toward cpython, and we'd nreak again.

So, two things:
  - their check is wrong,
  - we probably need host-pycparser

At least, that's what I understood...

Regards,
Yann E. MORIN.

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