Fix Memory Leak Caused By Wrong Limited API Default

When a type has nullptr as tp_dealloc, there apply different defaults.

Static types had object_dealloc as default, while new heaptypes
created with type_new have subtype_dealloc as default.

A problem was now that PyType_FromSpec also has
subtype_dealloc as default. But that is wrong, because a type that
was written with the static type approach is already written with
object_dealloc in mind and takes somehow care about further issues
with that type.

When we now convert this type and suddenly use subtype_dealloc
instead of object_dealloc, things get pretty wrong.

Finding that out was pretty hard and took quite long to understand.

The fix was then very easy and is the best proof:
Replacing our former (wrong) solution of supplying an
SbkDummyDealloc with a function object_dealloc works perfectly,
and the leakage completely vanished.

The documentation now is also corrected.

Task-number: PYSIDE-832
Change-Id: Ifc20c28172eb5663cd5e60dac52e0a43acfb626c
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

6 files changed, 8 insertions, 8 deletions

diff --git a/sources/pyside2/libpyside/pysideclassinfo.cpp b/sources/pyside2/libpyside/pysideclassinfo.cpp
index 24a0c642b..5593825c3 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 *)SbkDummyDealloc},
+    {Py_tp_dealloc, (void *)object_dealloc},
     {0, 0}
 };
 static PyType_Spec PySideClassInfoType_spec = {
diff --git a/sources/pyside2/libpyside/pysidemetafunction.cpp b/sources/pyside2/libpyside/pysidemetafunction.cpp
index 9839a1098..a9fbbc7fc 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 *)SbkDummyDealloc},
+    {Py_tp_dealloc, (void *)object_dealloc},
     {0, 0}
 };
 static PyType_Spec PySideMetaFunctionType_spec = {
diff --git a/sources/pyside2/libpyside/pysideqflags.cpp b/sources/pyside2/libpyside/pysideqflags.cpp
index 7a8fa2a05..684628e57 100644
--- a/sources/pyside2/libpyside/pysideqflags.cpp
+++ b/sources/pyside2/libpyside/pysideqflags.cpp
@@ -151,7 +151,7 @@ namespace QFlags
 #endif
         {Py_tp_new, (void *)PySideQFlagsNew},
         {Py_tp_richcompare, (void *)PySideQFlagsRichCompare},
-        {Py_tp_dealloc, (void *)SbkDummyDealloc},
+        {Py_tp_dealloc, (void *)object_dealloc},
         {0, 0}
     };
     static PyType_Spec SbkNewQFlagsType_spec = {
diff --git a/sources/pyside2/libpyside/pysidesignal.cpp b/sources/pyside2/libpyside/pysidesignal.cpp
index 2d423a634..c3dc65968 100644
--- a/sources/pyside2/libpyside/pysidesignal.cpp
+++ b/sources/pyside2/libpyside/pysidesignal.cpp
@@ -103,7 +103,7 @@ static PyType_Slot PySideSignalMetaType_slots[] = {
     {Py_tp_methods, (void *)Signal_methods},
     {Py_tp_base, (void *)&PyType_Type},
     {Py_tp_free, (void *)PyObject_GC_Del},
-    {Py_tp_dealloc, (void *)SbkDummyDealloc},
+    {Py_tp_dealloc, (void *)object_dealloc},
     {0, 0}
 };
 static PyType_Spec PySideSignalMetaType_spec = {
@@ -135,7 +135,7 @@ 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 *)SbkDummyDealloc},
+    {Py_tp_dealloc, (void *)object_dealloc},
     {0, 0}
 };
 static PyType_Spec PySideSignalType_spec = {
@@ -174,7 +174,7 @@ 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 *)SbkDummyDealloc},
+    {Py_tp_dealloc, (void *)object_dealloc},
     {0, 0}
 };
 static PyType_Spec PySideSignalInstanceType_spec = {
diff --git a/sources/pyside2/libpyside/pysideslot.cpp b/sources/pyside2/libpyside/pysideslot.cpp
index fddff54fa..6ae664c42 100644
--- a/sources/pyside2/libpyside/pysideslot.cpp
+++ b/sources/pyside2/libpyside/pysideslot.cpp
@@ -66,7 +66,7 @@ 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 *)SbkDummyDealloc},
+    {Py_tp_dealloc, (void *)object_dealloc},
     {0, 0}
 };
 static PyType_Spec PySideSlotType_spec = {
diff --git a/sources/pyside2/libpyside/pysideweakref.cpp b/sources/pyside2/libpyside/pysideweakref.cpp
index 906aafd7c..6c38d39c4 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 *)SbkDummyDealloc},
+    {Py_tp_dealloc, (void *)object_dealloc},
     {0, 0}
 };
 static PyType_Spec PySideCallableObjectType_spec = {