Fix for “sip.wrapinstance on Maya main window causes a hard crash”

Few month back, I wrote instructions to build PyQT for Maya 2014, but couple of weeks later someone came with a problem in using SIP with Maya. The issue was that Maya is crashing when someone tries to get the Maya handle and bind it using sip. I.e.:

import sip as _sip
import PyQt4.QtCore as _QtCore
import PyQt4.QtGui as _QtGui
import maya.OpenMayaUI as _OpenMayaUI
mainWindow = _sip.wrapinstance(long(_OpenMayaUI.MQtUtil.mainWindow()), _QtCore.QObject)

Hopefully, a colleague of mine Yves Boudreault investigated the issue and found a fix. The error resides in the sip code that is extracting address into a “unsigned long” instead of “unsigned long long”. I.e.: siplib.c.in

/*
* Wrap an instance.
*/
static PyObject *wrapInstance(PyObject *self, PyObject *args)
{
unsigned long addr;
sipWrapperType *wt;
if (PyArg_ParseTuple(args, "kO!:wrapinstance", &addr, &sipWrapperType_Type, &wt))
return sip_api_convert_from_type((void *)addr, wt->type, NULL);
return NULL;
}

and this is because Maya runs on x64 vs win32. The fix is easy, see below:

Fixed code for 64 bit ( unsigned long” -> “unsigned long long” and “kO!:wrapinstance” -> “KO!:wrapinstance” )

/*
* Wrap an instance.
*/
static PyObject *wrapInstance(PyObject *self, PyObject *args)
{
unsigned long long addr;
sipWrapperType *wt;
if (PyArg_ParseTuple(args, "KO!:wrapinstance", &addr, &sipWrapperType_Type, &wt))
return sip_api_convert_from_type((void *)addr, wt->type, NULL);
return NULL;
}

The fix has been posted on the Riverbank’s pyQt mailing list.