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, 6 insertions, 4 deletions

diff --git a/sources/shiboken2/tests/otherbinding/typediscovery_test.py b/sources/shiboken2/tests/otherbinding/typediscovery_test.py
index 6816b158a..a9eb88d80 100644
--- a/sources/shiboken2/tests/otherbinding/typediscovery_test.py
+++ b/sources/shiboken2/tests/otherbinding/typediscovery_test.py
@@ -51,14 +51,16 @@ class TypeDiscoveryTest(unittest.TestCase):
     def testMultipleInheritance(self):
         obj = OtherMultipleDerived.createObject("Base1");
         self.assertEqual(type(obj), Base1)
+        # PYSIDE-868: In case of multiple inheritance, a factory
+        # function will return the base class wrapper.
         obj = OtherMultipleDerived.createObject("MDerived1");
-        self.assertEqual(type(obj), MDerived1)
+        self.assertEqual(type(obj), Base1)
         obj = OtherMultipleDerived.createObject("SonOfMDerived1");
-        self.assertEqual(type(obj), SonOfMDerived1)
+        self.assertEqual(type(obj), Base1)
         obj = OtherMultipleDerived.createObject("MDerived3");
-        self.assertEqual(type(obj), MDerived3)
+        self.assertEqual(type(obj), Base1)
         obj = OtherMultipleDerived.createObject("OtherMultipleDerived");
-        self.assertEqual(type(obj), OtherMultipleDerived)
+        self.assertEqual(type(obj), Base1)
 
 if __name__ == '__main__':
     unittest.main()