On 03/18/2012 04:41 AM, Guannan Ren wrote:
+ if (totalbool == Py_False) { Per other code in libvirt-override.c, you can't compare totalbool (type PyObject) with Py_False, at least not on all compilers. You need something like this instead:
/* Hack - Python's definition of Py_True breaks strict * aliasing rules, so can't directly compare */ if (PyBool_Check(value)) { PyObject *hacktrue = PyBool_FromLong(1); temp->value.b = hacktrue == value ? 1 : 0; Py_DECREF(hacktrue);
Yes, it did report warning in compiling as follows due to the case from PyIntObject* to PyObject* warning :dereferencing type-punned pointer might break strict-aliasing rules [-Wstrict-aliasing]
And that would trip up a -Werror compilation, so I'm glad to see you changed it in v3.
GCC command line to reproduce the error: gcc -Wstrict-aliasing=1 -O2 cpythonexample.c
Actually PyObject_IsTrue() is a more light-weight approach to do the checking instead of creating a intermediate PyObject * for the compare.
Is PyObject_IsTrue() available in the version of python present on RHEL 5? If so, I'd be in favor of a followup cleanup patch that removes all our hacks in favor of the python glue code that does the same thing. And even if not, we should write a decent wrapper in our own typewrappers.c, so that the rest of our code doesn't have to look so ugly with so much copy-and-paste. -- Eric Blake eblake@redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org