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 [email protected] +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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