Fix bug 953 - "Segfault when QObject is garbage collected after QTimer.singeShot"

Reviewer: Renato Araújo <renato.filho@openbossa.org>
          Luciano Wolf <luciano.wolf@openbossa.org>

libpyside/signalmanager.cpp

@@ -323,11 +323,13 @@ int SignalManager::qt_metacall(QObject* object, QMetaObject::Call call, int id,
     PyObject* pp_name = 0;
     QMetaProperty mp;
     PyObject* pySelf = 0;
+    int methodCount = metaObject->methodCount();
+    int propertyCount = metaObject->propertyCount();
 
     if (call != QMetaObject::InvokeMetaMethod) {
         mp = metaObject->property(id);
         if (!mp.isValid())
-            return id - metaObject->methodCount();
+            return id - methodCount;
 
         Shiboken::GilState gil;
         pySelf = (PyObject*)Shiboken::BindingManager::instance().retrieveWrapper(object);
@@ -337,7 +339,7 @@ int SignalManager::qt_metacall(QObject* object, QMetaObject::Call call, int id,
         if (!pp) {
             qWarning("Invalid property: %s.", mp.name());
             Py_XDECREF(pp_name);
-            return id - metaObject->methodCount();
+            return id - methodCount;
         }
     }
 
@@ -362,10 +364,13 @@ int SignalManager::qt_metacall(QObject* object, QMetaObject::Call call, int id,
             qWarning("Unsupported meta invocation type.");
     }
 
+    // WARNING Isn't safe to call any metaObject and/or object methods beyond this point
+    //         because the object can be deleted inside the called slot.
+
     if (call == QMetaObject::InvokeMetaMethod)
-        id = id - metaObject->methodCount();
+        id = id - methodCount;
     else
-        id = id - metaObject->propertyCount();
+        id = id - propertyCount;
 
     if (pp || pp_name) {
         Shiboken::GilState gil;

tests/QtCore/CMakeLists.txt

@@ -20,6 +20,7 @@ PYSIDE_TEST(bug_920.py)
 PYSIDE_TEST(bug_927.py)
 PYSIDE_TEST(bug_931.py)
 PYSIDE_TEST(bug_938.py)
+PYSIDE_TEST(bug_953.py)
 PYSIDE_TEST(blocking_signals_test.py)
 PYSIDE_TEST(classinfo_test.py)
 PYSIDE_TEST(child_event_test.py)

tests/QtCore/bug_953.py

@@ -0,0 +1,18 @@
+from PySide.QtCore import *
+
+class Dispatcher(QObject):
+    _me = None
+
+    def __init__(self):
+        super(Dispatcher, self).__init__()
+        self._me = self
+        QTimer.singleShot(0, self._finish)
+
+    def _finish(self):
+        del self._me # It can't crash here!
+        QTimer.singleShot(10, QCoreApplication.instance().quit)
+
+if __name__ == '__main__':
+    app = QCoreApplication([])
+    Dispatcher()
+    app.exec_()