Fix crash related to multiple inheritance

In the <class>_PTR_CppToPython_<class> converter function (written by
CppGenerator::writeConverterFunctions()), the generated code
used typeid(*ptr).name() to retrieve the name to use for the
SbkObjectTypes. This construct returns the name of the outermost
class (for example, "QWidget" for a QWidget-type paint device returned
by QPainter::device()), as opposed to "QPaintDevice *" returned by
typeid(ptr).name(). This caused a crash with multiple inheritance
since QWidget inherits QObject and QPaintDevice and the "QWidget"
type was associated with the QPaintDevice pointer.

To fix this:
- Add API to libshiboken to obtain the SbkObjectType* by name
  and check for the presence of a special cast function (multiple
  inheritance).
- Generate the code of <class>_PTR_CppToPython_<class> as follows:
  Check whether the outermost type obtained by typeid(*ptr).name()
  has a special cast function. If that is the case, use the
  type name obtained by typeid(ptr).name() (base class) to create
  the wrapper.

Change-Id: I8ee6b4c084e9dafa434623433661809b83aedee5
Fixes: PYSIDE-868
Reviewed-by: Cristian Maureira-Fredes <cristian.maureira-fredes@qt.io>

1 files changed, 23 insertions, 2 deletions

diff --git a/sources/pyside2/tests/QtWidgets/qgraphicsscene_test.py b/sources/pyside2/tests/QtWidgets/qgraphicsscene_test.py
index 07926d177..80a09dc57 100644
--- a/sources/pyside2/tests/QtWidgets/qgraphicsscene_test.py
+++ b/sources/pyside2/tests/QtWidgets/qgraphicsscene_test.py
@@ -32,14 +32,14 @@ import unittest
 import gc
 
 from PySide2.QtCore import QPointF
-from PySide2.QtGui import QPolygonF, QPixmap, QPainterPath, QTransform
+from PySide2.QtGui import QPolygonF, QPixmap, QPainterPath, QTransform, QWindow
 from PySide2.QtWidgets import QApplication, QPushButton
 from PySide2.QtWidgets import QGraphicsScene
 from PySide2.QtWidgets import QGraphicsEllipseItem, QGraphicsLineItem
 from PySide2.QtWidgets import QGraphicsPathItem, QGraphicsPixmapItem
 from PySide2.QtWidgets import QGraphicsPolygonItem, QGraphicsRectItem
 from PySide2.QtWidgets import QGraphicsSimpleTextItem, QGraphicsTextItem
-from PySide2.QtWidgets import QGraphicsProxyWidget
+from PySide2.QtWidgets import QGraphicsProxyWidget, QGraphicsView
 
 from helper import UsesQApplication
 
@@ -51,6 +51,19 @@ class Constructor(unittest.TestCase):
         obj = QGraphicsScene()
         self.assertTrue(isinstance(obj, QGraphicsScene))
 
+# Test for PYSIDE-868: Test whether painter.device() can be accessed
+# correctly. This was crashing when the underlying QPaintDevice was a
+# QWidget due to handling multiple inheritance incorrectly.
+class CustomScene(QGraphicsScene):
+    def __init__(self, parent = None):
+        super(CustomScene, self).__init__(parent)
+        self.dpi = 0
+
+    def drawBackground(self, painter, rect):
+        self.dpi = painter.device().physicalDpiX()
+
+    def drawForeground(self, painter, rect):
+        self.dpi = painter.device().physicalDpiX()
 
 class ConstructorWithRect(unittest.TestCase):
     '''QGraphicsScene qrect constructor and related sizes'''
@@ -192,6 +205,14 @@ class TestGraphicsGroup(UsesQApplication):
         scene.destroyItemGroup(group)
         self.assertRaises(RuntimeError, group.type)
 
+    def testCustomScene(self): # For PYSIDE-868, see above
+        scene = CustomScene()
+        view = QGraphicsView(scene)
+        view.show()
+        while scene.dpi == 0:
+           QApplication.instance().processEvents()
+        view.hide()
+
 
 if __name__ == '__main__':
     unittest.main()