Fix Python 3.8 problems

This patch fixes some refcounting problems with Python 3.8 .
One incompatible change was announced in the what's new
document, but actually there were two more problems which
were not explicitly mentioned but took much time to sort out.

The patch is compatible with the limited API changes
(tested with debug build and API error disabled).
It is also independent of the Python version which is
full Limited API support.

For more info, see the documentation mentioned below.

The flag error is circumvented now! We either find a better
solution or leave it as it is. For now this is ok.

Fixes: PYSIDE-939
Change-Id: Iff4a9816857a6ebe86efd4b654d8921e4e464939
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Cristian Maureira-Fredes <cristian.maureira-fredes@qt.io>

9 files changed, 27 insertions, 14 deletions

diff --git a/sources/pyside2/PySide2/QtQml/pysideqmlregistertype.cpp b/sources/pyside2/PySide2/QtQml/pysideqmlregistertype.cpp
index 6427e5198..fb9a5a0cf 100644
--- a/sources/pyside2/PySide2/QtQml/pysideqmlregistertype.cpp
+++ b/sources/pyside2/PySide2/QtQml/pysideqmlregistertype.cpp
@@ -236,7 +236,7 @@ void propListTpFree(void *self)
 static PyType_Slot PropertyListType_slots[] = {
     {Py_tp_init, (void *)propListTpInit},
     {Py_tp_free, (void *)propListTpFree},
-    {Py_tp_dealloc, (void *)object_dealloc},
+    {Py_tp_dealloc, (void *)Sbk_object_dealloc},
     {0, 0}
 };
 static PyType_Spec PropertyListType_spec = {
@@ -450,7 +450,7 @@ static PyType_Slot QtQml_VolatileBoolType_slots[] = {
     {Py_tp_str, (void *)reinterpret_cast<reprfunc>(QtQml_VolatileBoolObject_str)},
     {Py_tp_methods, (void *)QtQml_VolatileBoolObject_methods},
     {Py_tp_new, (void *)QtQml_VolatileBoolObject_new},
-    {Py_tp_dealloc, (void *)object_dealloc},
+    {Py_tp_dealloc, (void *)Sbk_object_dealloc},
     {0, 0}
 };
 static PyType_Spec QtQml_VolatileBoolType_spec = {
diff --git a/sources/pyside2/libpyside/pysideclassinfo.cpp b/sources/pyside2/libpyside/pysideclassinfo.cpp
index fe5ca8765..c4bace77e 100644
--- a/sources/pyside2/libpyside/pysideclassinfo.cpp
+++ b/sources/pyside2/libpyside/pysideclassinfo.cpp
@@ -60,7 +60,7 @@ static PyType_Slot PySideClassInfoType_slots[] = {
     {Py_tp_init, (void *)classInfoTpInit},
     {Py_tp_new, (void *)classInfoTpNew},
     {Py_tp_free, (void *)classInfoFree},
-    {Py_tp_dealloc, (void *)object_dealloc},
+    {Py_tp_dealloc, (void *)Sbk_object_dealloc},
     {0, 0}
 };
 static PyType_Spec PySideClassInfoType_spec = {
diff --git a/sources/pyside2/libpyside/pysidemetafunction.cpp b/sources/pyside2/libpyside/pysidemetafunction.cpp
index e0e0c439b..637aa0598 100644
--- a/sources/pyside2/libpyside/pysidemetafunction.cpp
+++ b/sources/pyside2/libpyside/pysidemetafunction.cpp
@@ -62,7 +62,7 @@ static PyType_Slot PySideMetaFunctionType_slots[] = {
     {Py_tp_call, (void *)functionCall},
     {Py_tp_new, (void *)PyType_GenericNew},
     {Py_tp_free, (void *)functionFree},
-    {Py_tp_dealloc, (void *)object_dealloc},
+    {Py_tp_dealloc, (void *)Sbk_object_dealloc},
     {0, 0}
 };
 static PyType_Spec PySideMetaFunctionType_spec = {
diff --git a/sources/pyside2/libpyside/pysideproperty.cpp b/sources/pyside2/libpyside/pysideproperty.cpp
index d9d15eb3b..009a17a3e 100644
--- a/sources/pyside2/libpyside/pysideproperty.cpp
+++ b/sources/pyside2/libpyside/pysideproperty.cpp
@@ -210,6 +210,11 @@ int qpropertyTpInit(PyObject *self, PyObject *args, PyObject *kwds)
 void qpropertyDeAlloc(PyObject *self)
 {
     qpropertyClear(self);
+    if (PepRuntime_38_flag) {
+        // PYSIDE-939: Handling references correctly.
+        // This was not needed before Python 3.8 (Python issue 35810)
+        Py_DECREF(Py_TYPE(self));
+    }
     Py_TYPE(self)->tp_free(self);
 }
 
diff --git a/sources/pyside2/libpyside/pysideqflags.cpp b/sources/pyside2/libpyside/pysideqflags.cpp
index fd0ed005f..33351440a 100644
--- a/sources/pyside2/libpyside/pysideqflags.cpp
+++ b/sources/pyside2/libpyside/pysideqflags.cpp
@@ -152,7 +152,7 @@ namespace QFlags
 #endif
         {Py_tp_new, (void *)PySideQFlagsNew},
         {Py_tp_richcompare, (void *)PySideQFlagsRichCompare},
-        {Py_tp_dealloc, (void *)object_dealloc},
+        {Py_tp_dealloc, (void *)Sbk_object_dealloc},
         {0, 0}
     };
     static PyType_Spec SbkNewQFlagsType_spec = {
diff --git a/sources/pyside2/libpyside/pysidesignal.cpp b/sources/pyside2/libpyside/pysidesignal.cpp
index ed1dcb729..ee435ab37 100644
--- a/sources/pyside2/libpyside/pysidesignal.cpp
+++ b/sources/pyside2/libpyside/pysidesignal.cpp
@@ -110,7 +110,7 @@ static PyType_Slot PySideMetaSignalType_slots[] = {
     {Py_tp_methods, (void *)MetaSignal_methods},
     {Py_tp_base, (void *)&PyType_Type},
     {Py_tp_free, (void *)PyObject_GC_Del},
-    {Py_tp_dealloc, (void *)object_dealloc},
+    {Py_tp_dealloc, (void *)Sbk_object_dealloc},
     {0, 0}
 };
 static PyType_Spec PySideMetaSignalType_spec = {
@@ -142,7 +142,7 @@ static PyType_Slot PySideSignalType_slots[] = {
     {Py_tp_init, (void *)signalTpInit},
     {Py_tp_new, (void *)PyType_GenericNew},
     {Py_tp_free, (void *)signalFree},
-    {Py_tp_dealloc, (void *)object_dealloc},
+    {Py_tp_dealloc, (void *)Sbk_object_dealloc},
     {0, 0}
 };
 static PyType_Spec PySideSignalType_spec = {
@@ -181,7 +181,7 @@ static PyType_Slot PySideSignalInstanceType_slots[] = {
     {Py_tp_methods, (void *)SignalInstance_methods},
     {Py_tp_new, (void *)PyType_GenericNew},
     {Py_tp_free, (void *)signalInstanceFree},
-    {Py_tp_dealloc, (void *)object_dealloc},
+    {Py_tp_dealloc, (void *)Sbk_object_dealloc},
     {0, 0}
 };
 static PyType_Spec PySideSignalInstanceType_spec = {
@@ -619,7 +619,7 @@ void init(PyObject *module)
 {
     if (SbkSpecial_Type_Ready(module, PySideMetaSignalTypeF(), MetaSignal_SignatureStrings) < 0)
         return;
-    Py_INCREF(PySideSignalTypeF());
+    Py_INCREF(PySideMetaSignalTypeF());
     PyModule_AddObject(module, "MetaSignal", reinterpret_cast<PyObject *>(PySideMetaSignalTypeF()));
 
     if (SbkSpecial_Type_Ready(module, PySideSignalTypeF(), Signal_SignatureStrings) < 0)
diff --git a/sources/pyside2/libpyside/pysideslot.cpp b/sources/pyside2/libpyside/pysideslot.cpp
index 204253aa2..04212a64e 100644
--- a/sources/pyside2/libpyside/pysideslot.cpp
+++ b/sources/pyside2/libpyside/pysideslot.cpp
@@ -71,7 +71,7 @@ static PyType_Slot PySideSlotType_slots[] = {
     {Py_tp_call, (void *)slotCall},
     {Py_tp_init, (void *)slotTpInit},
     {Py_tp_new, (void *)PyType_GenericNew},
-    {Py_tp_dealloc, (void *)object_dealloc},
+    {Py_tp_dealloc, (void *)Sbk_object_dealloc},
     {0, 0}
 };
 static PyType_Spec PySideSlotType_spec = {
diff --git a/sources/pyside2/libpyside/pysideweakref.cpp b/sources/pyside2/libpyside/pysideweakref.cpp
index 2b27f9545..faa3abe82 100644
--- a/sources/pyside2/libpyside/pysideweakref.cpp
+++ b/sources/pyside2/libpyside/pysideweakref.cpp
@@ -53,7 +53,7 @@ static PyObject *CallableObject_call(PyObject *callable_object, PyObject *args,
 
 static PyType_Slot PySideCallableObjectType_slots[] = {
     {Py_tp_call, (void *)CallableObject_call},
-    {Py_tp_dealloc, (void *)object_dealloc},
+    {Py_tp_dealloc, (void *)Sbk_object_dealloc},
     {0, 0}
 };
 static PyType_Spec PySideCallableObjectType_spec = {
@@ -94,9 +94,15 @@ PyObject *create(PyObject *obj, PySideWeakRefFunction func, void *userData)
         PyType_Ready(PySideCallableObjectTypeF());
     }
 
-    PySideCallableObject *callable = PyObject_New(PySideCallableObject, PySideCallableObjectTypeF());
+    PyTypeObject *type = PySideCallableObjectTypeF();
+    PySideCallableObject *callable = PyObject_New(PySideCallableObject, type);
     if (!callable || PyErr_Occurred())
         return 0;
+    if (!PepRuntime_38_flag) {
+        // PYSIDE-939: Handling references correctly.
+        // Workaround for Python issue 35810; no longer necessary in Python 3.8
+        Py_INCREF(type);
+    }
 
     PyObject *weak = PyWeakref_NewRef(obj, reinterpret_cast<PyObject *>(callable));
     if (!weak || PyErr_Occurred())
diff --git a/sources/pyside2/tests/signals/bug_79.py b/sources/pyside2/tests/signals/bug_79.py
index 9eb783d77..4a595912c 100644
--- a/sources/pyside2/tests/signals/bug_79.py
+++ b/sources/pyside2/tests/signals/bug_79.py
@@ -56,13 +56,15 @@ class ConnectTest(unittest.TestCase):
         # if this is no debug build, then we check at least that
         # we do not crash any longer.
         if not skiptest:
-            total = sys.gettotalrefcount()
+            total = gettotalrefcount()
         for idx in range(1000):
             o.selectionModel().destroyed.connect(self.callback)
             o.selectionModel().destroyed.disconnect(self.callback)
         gc.collect()
         if not skiptest:
-            self.assertTrue(abs(gettotalrefcount() - total) < 10)
+            delta = gettotalrefcount() - total
+            print("delta total refcount =", delta)
+            self.assertTrue(abs(delta) < 10)
 
 
 if __name__ == '__main__':