SWIG_init() returns void for Python 2.x and 'PyObject *' for Python 3.
Use an #if to handle both cases properly, otherwise the Python bindings
for either Python 2 or 3 will fail to build.
Python 3.x failure:
sigrok/core/classes_wrap.cpp: In function ‘PyObject* PyInit__classes()’:
sigrok/core/classes_wrap.cpp:59002:5: error: return-statement with no
value, in function returning ‘PyObject* {aka _object*}’ [-fpermissive]
return;
^
Python 2.x failure:
In file included from /usr/include/dirent.h:244:0,
from /usr/include/glib-2.0/glib/gdir.h:32,
from /usr/include/glib-2.0/glib.h:45,
from /usr/include/pygobject-3.0/pygobject.h:7,
from sigrok/core/classes_wrap.cpp:3179:
sigrok/core/classes_wrap.cpp: In function ‘void init_classes()’:
sigrok/core/classes_wrap.cpp:59002:12: error: return-statement with a
value, in function returning 'void' [-fpermissive]
return NULL;
^
When the import of gi.repository.GLib failed, we would get a NULL
pointer that we passed along without any checking. In this situation,
the entire program would crash with a segmentation fault, and no
message to indicate the problem.
When the import fails, abort the SWIG init and print a message. The
Python interpreter then prints out a backtrace, which can be useful
in tracking down the problem.
Uwe Hermann
Alexandru Gagniuc
Martin Ling
Marcus Comstedt