[PyQt] PyQt & Twisted

[Christian Caron]

I used to have this crash rather infrequently but it got more frequent  
when I moved to PyQt 4.6 / Snow Leopard.

Configuration
---------------------
Mac OSX 10.6.1
Qt 4.5.3
sip-4.9.1-snapshot-20091007
PyQt-mac-gpl-4.6.1-snapshot-20091007

Crash
-----------

My investigation so far shows that PyQtProxy::unislot deletes memory  
that was already deleted (in attempting to self destruct).

Exception Type:  EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0x0000000000000028
Crashed Thread:  0  Dispatch queue: com.apple.main-thread

Thread 0 Crashed:  Dispatch queue: com.apple.main-thread
0   QtCore.so                     	0x00000001030db619  
PyQtProxy::unislot(void**) + 133
1   QtCore.so                     	0x00000001030db6f5  
PyQtProxy::qt_metacall(QMetaObject::Call, int, void**) + 119
2   QtCore                        	0x00000001005c1183  
QMetaObject::activate(QObject*, int, int, void**) + 675
3   QtCore.so                     	0x000000010302ae97  
sipQTimer::timerEvent(QTimerEvent*) + 77
4   QtCore                        	0x00000001005bf19e QObject::event 
(QEvent*) + 446
5   QtCore.so                     	0x000000010302ae2d sipQTimer::event 
(QEvent*) + 77
6   QtGui                         	0x00000001019fd3ed  
QApplicationPrivate::notify_helper(QObject*, QEvent*) + 189
7   QtGui                         	0x0000000101a0405e  
QApplication::notify(QObject*, QEvent*) + 238
8   QtGui.so                      	0x000000010136e1d1  
sipQApplication::notify(QObject*, QEvent*) + 95
9   QtCore                        	0x00000001005aec3c  
QCoreApplication::notifyInternal(QObject*, QEvent*) + 124

Repro
-----------
Using the qt4reactor found here: http://twistedmatrix.com/trac/browser/sandbox/therve/qt4reactor.py?rev=22736&format=txt
You may need to run the program a few times for it to crash.

import qt4reactor
qt4reactor.install()

# Control-C
from twisted.internet import reactor
import signal; signal.signal(signal.SIGINT, lambda *args:reactor.stop())

# Get web page.
from twisted.web import client
url = 'http://www.google.com'
client.getPage(url)

reactor.run()
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