fix the signatures of the METH_NOARGS callbacks

Various Python method callbacks have signatures of the form:

  static PyObject *
  foo(some_object_subclass *obj)

and are registered within the PyMethodDef tables with the METH_NOARGS
flag [1], with a cast to (PyCFunction) due to the PyObject/subclass
mismatch.

However, such callbacks do receive two arguments: they are invoked with
a signature of this form:

  static PyObject *
  foo(some_object_subclass *obj, PyObject *ignored)

The CPython interpreter only uses METH_NOARGS to allow it to pass NULL as the
second parameter: there are still two parameters.  The dispatch code is in
Python's Python/ceval.c:call_function:

            if (flags & METH_NOARGS && na == 0) {
                C_TRACE(x, (*meth)(self,NULL));
            }

The fact that this has ever worked may be a coincidence of the
platform/compiler's calling conventions, and I don't think it's guaranteed to
keep working.

[1] http://docs.python.org/c-api/structures.html#METH_NOARGS

Signed-off-by: Ales Kozumplik <akozumpl@redhat.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/python/rpmmi-py.c b/python/rpmmi-py.c
index 977e47552..8e670ce02 100644
--- a/python/rpmmi-py.c
+++ b/python/rpmmi-py.c
@@ -78,7 +78,7 @@ rpmmi_iternext(rpmmiObject * s)
 }
 
 static PyObject *
-rpmmi_Instance(rpmmiObject * s)
+rpmmi_Instance(rpmmiObject * s, PyObject * unused)
 {
     int rc = 0;
 
@@ -89,7 +89,7 @@ rpmmi_Instance(rpmmiObject * s)
 }
 
 static PyObject *
-rpmmi_Count(rpmmiObject * s)
+rpmmi_Count(rpmmiObject * s, PyObject * unused)
 {
     DEPRECATED_METHOD("use len(mi) instead");
     return Py_BuildValue("i", PyMapping_Size((PyObject *)s));