Build failed (archlinux) about python-gphoto2

[jim-easterbrook]

What version of SWIG are you using?

[sciunto]

swig 3.0.7

[jim-easterbrook]

I'm still on 3.0.2. I'll investigate further. Meanwhile, does editing setup.py and removing '-Wextra' and '-Werror' from swig_opts help?

[sciunto]

No. I have to also remove Werror in extra_compile_args, and then I only get warnings.

Thanks.

[jim-easterbrook]

I need to set up an archlinux virtual machine to sort this out properly. This may take some time.

[jim-easterbrook]

I've established that it's not the different SWIG versions that's the problem, but most likely the different gcc versions (4.8.3 on my OpenSUSE machine vs 5.2.0 on archlinux).

[jim-easterbrook]

I've found that some of the warnings (e.g. "missing braces around initializer") are easily disabled and probably inconsequential. However, the "excess elements in struct initializer" warnings are more serious. Ignoring all errors means the build and install appears to work, but the python module produced does not work correctly.
My archlinux machine has Python 3.5, which introduces a new member (PyAsyncMethods as_async) into the PyHeapTypeObject struct defined in /usr/include/python3.5m/object.h. Removing this member stops the "excess elements in struct initializer" warnings and produces a working python module. This is not a solution!
It appears that SWIG is not aware of this difference between python 3.5 & python 3.4, and so is wrongly defining its version of the python type structs.

[sciunto]

Nice investigations.
SWIG does not seem to have any ticket related to async. It's probably worth to talk to them.

[jim-easterbrook]

A more legitimate workaround is to not use SWIG's '-builtin' option. This makes wrappers that don't use PyHeapTypeObject at all. My problem is that the PyPI releases of python-gphoto2 include the SWIG output (to reduce the dependencies users need) and the -builtin option provides a worthwhile improvement for most Python versions.
I'll modify setup.py to drop the -builtin option for Python 3.5 users who are building from source. This will be a temporary fix until SWIG catches up.

[jim-easterbrook]

I've released version 1.2.2 that should use -builtin only where it's known to be safe. I'll submit a bug report to SWIG when I've made a suitable small example to illustrate the problem.

[sciunto]

I successfully built the package with 1.2.2. Thank you for quick fix!

[jim-easterbrook]

See swig/swig#539.