sbkenum: Fix refcounting leak

sbkenum had a wrong deallocator and some other errors.
Found while developing pickling on enums.

At the same time, a wrong Python 3.8 condition was removed.
There are currently no additional bugs in Python 2.7, 3.7 and 3.8.

Change-Id: I4abccf3b84a3738bba7781ea3dfd00e98ae63ea1
Reviewed-by: Christian Tismer <tismer@stackless.com>

3 files changed, 29 insertions, 16 deletions

diff --git a/sources/pyside2/libpyside/pysideweakref.cpp b/sources/pyside2/libpyside/pysideweakref.cpp
index 84b390e96..cd90634bd 100644
--- a/sources/pyside2/libpyside/pysideweakref.cpp
+++ b/sources/pyside2/libpyside/pysideweakref.cpp
@@ -98,11 +98,6 @@ PyObject *create(PyObject *obj, PySideWeakRefFunction func, void *userData)
     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/QtCore/qenum_test.py b/sources/pyside2/tests/QtCore/qenum_test.py
index ed58f4f20..1edb8981a 100644
--- a/sources/pyside2/tests/QtCore/qenum_test.py
+++ b/sources/pyside2/tests/QtCore/qenum_test.py
@@ -30,6 +30,7 @@
 
 '''Test cases for QEnum and QFlags'''
 
+import gc
 import os
 import sys
 import pickle
@@ -75,6 +76,22 @@ class TestEnum(unittest.TestCase):
         with self.assertRaises(TypeError):
             a = k*2.0
 
+    @unittest.skipUnless(getattr(sys, "getobjects", None), "requires debug build")
+    def testEnumNew_NoLeak(self):
+        gc.collect()
+        total = sys.gettotalrefcount()
+        for idx in range(1000):
+            ret = Qt.Key(42)
+        gc.collect()
+        delta = sys.gettotalrefcount() - total
+        print("delta total refcount =", delta)
+        if abs(delta) >= 10:
+            all = sys.getobjects(0)
+            all.sort(key=lambda x: sys.getrefcount(x), reverse=True)
+            for ob in all[:10]:
+                print(sys.getrefcount(ob), ob)
+        self.assertTrue(abs(delta) < 10)
+
 
 class TestQFlags(unittest.TestCase):
     def testToItn(self):
diff --git a/sources/shiboken2/libshiboken/sbkenum.cpp b/sources/shiboken2/libshiboken/sbkenum.cpp
index 5b9718738..36f2f48f9 100644
--- a/sources/shiboken2/libshiboken/sbkenum.cpp
+++ b/sources/shiboken2/libshiboken/sbkenum.cpp
@@ -107,16 +107,18 @@ static PyObject *SbkEnum_tp_new(PyTypeObject *type, PyObject *args, PyObject *)
     if (!self)
         return nullptr;
     self->ob_value = itemValue;
-    PyObject *item = Shiboken::Enum::getEnumItemFromValue(type, itemValue);
-    if (item) {
-        self->ob_name = SbkEnumObject_name(item, nullptr);
-        Py_XDECREF(item);
-    } else {
-        self->ob_name = nullptr;
-    }
+    Shiboken::AutoDecRef item(Shiboken::Enum::getEnumItemFromValue(type, itemValue));
+    self->ob_name = item.object() ? SbkEnumObject_name(item, nullptr) : nullptr;
     return reinterpret_cast<PyObject *>(self);
 }
 
+void enum_object_dealloc(PyObject *ob)
+{
+    auto self = reinterpret_cast<SbkEnumObject *>(ob);
+    Py_XDECREF(self->ob_name);
+    Sbk_object_dealloc(ob);
+}
+
 static PyObject *enum_op(enum_func f, PyObject *a, PyObject *b) {
     PyObject *valA = a;
     PyObject *valB = b;
@@ -448,7 +450,7 @@ static bool _init_enum()
 static void init_enum()
 {
     if (!(enum_unpickler || _init_enum()))
-        Py_FatalError("could not load enum helper functions");
+        Py_FatalError("could not load enum pickling helper function");
 }
 
 static PyMethodDef SbkEnumObject_Methods[] = {
@@ -497,7 +499,7 @@ PyObject *getEnumItemFromValue(PyTypeObject *enumType, long itemValue)
     while (PyDict_Next(values, &pos, &key, &value)) {
         auto *obj = reinterpret_cast<SbkEnumObject *>(value);
         if (obj->ob_value == itemValue) {
-            Py_INCREF(obj);
+            Py_INCREF(value);
             return value;
         }
     }
@@ -644,7 +646,7 @@ static PyType_Slot SbkNewType_slots[] = {
     {Py_nb_index, (void *)enum_int},
     {Py_tp_richcompare, (void *)enum_richcompare},
     {Py_tp_hash, (void *)enum_hash},
-    {Py_tp_dealloc, (void *)Sbk_object_dealloc},
+    {Py_tp_dealloc, (void *)enum_object_dealloc},
     {0, nullptr}
 };
 static PyType_Spec SbkNewType_spec = {
@@ -735,7 +737,6 @@ newTypeWithName(const char *name,
     newspec->slots = newslots;
     auto *type = reinterpret_cast<PyTypeObject *>(SbkType_FromSpec(newspec));
     Py_TYPE(type) = SbkEnumType_TypeF();
-    Py_INCREF(Py_TYPE(type));
 
     auto *enumType = reinterpret_cast<SbkEnumType *>(type);
     PepType_SETP(enumType)->cppName = cppName;