[Buildroot] socket.AF_BLUETOOTH in python3 and circular dependencies

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

Thomas, Grzegorz, All,

On 2018-09-01 00:10 +0200, Thomas Petazzoni spake thusly:
> On Thu, 30 Aug 2018 21:21:23 +0200, Grzegorz Blach wrote:
> > But unfortunately this patch makes a circular dependencies:
> > $ make python3-graph-depends
> > Recursion detected for  : bluez5_utils
> > which is a dependency of: python3
> > which is a dependency of: util-linux
> > which is a dependency of: libglib2
> > which is a dependency of: bluez5_utils
> Arghh, this is annoying :-/
> I don't see a good solution here. Possible options that I see at this
> point:
> 
>  (1) Change Python in Modules/socketmodule.c to not require
>      bluetooth.h. It doesn't seem to link with any Bluetooth library,
>      only to need bluetooth.h, so perhaps just like they do for
>      FreeBSD/NetBSD, we could add the necessary definitions directly in
>      socketmodule.c to avoid the bluetooth.h dependency ?
> 
>  (2) Create a python-util-linux package that would be responsible for
>      building the util-linux Python bindings. This would remove Python
>      from being a dependency of util-linux, and break the circular
>      dependency.
> 
>      However, it is not clear that it will be easy to tell
>      python-util-linux to *only* build the Python bindings and use the
>      existing libraries built by the util-linux package, rather than
>      rebuilding them again.
> 
>  (3) Add an explicit Config.in option for util-linux Python support,
>      and make it conflict with Bluetooth support in Python.

 (4) Create libutil-linux that just install the required libs, like
     libmount needed by libglib2, thus breaking the loop. I think this
     might be the simplest solution.

 (5) Create libbluez5_utils, which only installs the development files,
     so that python{,3} can depend on it. This would work, only if the
     libbluetooth.so is not itself linked to libglib2 (but only the
     bluetooth utils are). On my Ubuntu 17.10, it is not.

> For the record, OpenEmbedded doesn't support Bluetooth in Python socket
> module, they pass:
>   ac_cv_header_bluetooth_bluetooth_h=no ac_cv_header_bluetooth_h=no
> to the Python configure script.

Maybe we can do better? ;-)

Regards,
Yann E. MORIN.

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