Use PyType_GetSlot() instead of accessing PyTypeObject's slots in library code

Using PepType_GetSlot() as is requires adding ugly casts. To work
around, add a new file with convenience helper functions in C++
linkage. This also allows for using templates for tp_alloc.

Task-number: PYSIDE-560
Change-Id: Ia50a226f5b545861f885d600445b91b4e11713c5
Reviewed-by: Christian Tismer <tismer@stackless.com>

14 files changed, 130 insertions, 31 deletions

diff --git a/sources/pyside6/PySide6/QtQml/pysideqmlvolatilebool.cpp b/sources/pyside6/PySide6/QtQml/pysideqmlvolatilebool.cpp
index e92e13aaf..6e403ab72 100644
--- a/sources/pyside6/PySide6/QtQml/pysideqmlvolatilebool.cpp
+++ b/sources/pyside6/PySide6/QtQml/pysideqmlvolatilebool.cpp
@@ -3,6 +3,7 @@
 
 #include "pysideqmlvolatilebool.h"
 
+#include <pep384ext.h>
 #include <signature.h>
 
 #include <QtCore/QDebug>
@@ -30,8 +31,7 @@ QtQml_VolatileBoolObject_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
     if (ok < 0)
         return nullptr;
 
-    QtQml_VolatileBoolObject *self
-            = reinterpret_cast<QtQml_VolatileBoolObject *>(type->tp_alloc(type, 0));
+    auto *self = PepExt_TypeCallAlloc<QtQml_VolatileBoolObject>(type, 0);
 
     if (self != nullptr)
         self->flag = new AtomicBool(ok);
diff --git a/sources/pyside6/libpyside/class_property.cpp b/sources/pyside6/libpyside/class_property.cpp
index 99104445c..2bed97ef5 100644
--- a/sources/pyside6/libpyside/class_property.cpp
+++ b/sources/pyside6/libpyside/class_property.cpp
@@ -5,6 +5,7 @@
 #include "pysidestaticstrings.h"
 #include "feature_select.h"
 
+#include <pep384ext.h>
 #include <shiboken.h>
 #include <sbkstaticstrings.h>
 
@@ -23,14 +24,14 @@ extern "C" {
 // `class_property.__get__()`: Always pass the class instead of the instance.
 static PyObject *PyClassProperty_descr_get(PyObject *self, PyObject * /*ob*/, PyObject *cls)
 {
-    return PyProperty_Type.tp_descr_get(self, cls, cls);
+    return PepExt_Type_GetDescrGetSlot(&PyProperty_Type)(self, cls, cls);
 }
 
 // `class_property.__set__()`: Just like the above `__get__()`.
 static int PyClassProperty_descr_set(PyObject *self, PyObject *obj, PyObject *value)
 {
     PyObject *cls = PyType_Check(obj) ? obj : reinterpret_cast<PyObject *>(Py_TYPE(obj));
-    return PyProperty_Type.tp_descr_set(self, cls, value);
+    return PepExt_Type_GetDescrSetSlot(&PyProperty_Type)(self, cls, value);
 }
 
 // PYSIDE-2230: Why is this metaclass necessary?
@@ -80,7 +81,7 @@ static int PyClassProperty_tp_init(PyObject *self, PyObject *args, PyObject *kwa
 {
     auto hold = Py_TYPE(self);
     self->ob_type = &PyProperty_Type;
-    auto ret =  PyProperty_Type.tp_init(self, args, kwargs);
+    auto ret = PepExt_Type_GetInitSlot(&PyProperty_Type)(self, args, kwargs);
     self->ob_type = hold;
     return ret;
 }
@@ -138,9 +139,9 @@ static int SbkObjectType_meta_setattro(PyObject *obj, PyObject *name, PyObject *
                                 && !PyObject_IsInstance(value, class_prop);
     if (call_descr_set) {
         // Call `class_property.__set__()` instead of replacing the `class_property`.
-        return Py_TYPE(descr)->tp_descr_set(descr, obj, value);
+        return PepExt_Type_GetDescrSetSlot(Py_TYPE(descr))(descr, obj, value);
     } // Replace existing attribute.
-    return PyType_Type.tp_setattro(obj, name, value);
+    return PepExt_Type_GetSetAttroSlot(&PyType_Type)(obj, name, value);
 }
 
 } // extern "C"
diff --git a/sources/pyside6/libpyside/dynamicqmetaobject.cpp b/sources/pyside6/libpyside/dynamicqmetaobject.cpp
index b41dbc275..048001f81 100644
--- a/sources/pyside6/libpyside/dynamicqmetaobject.cpp
+++ b/sources/pyside6/libpyside/dynamicqmetaobject.cpp
@@ -634,7 +634,7 @@ void MetaObjectBuilderPrivate::parsePythonType(PyTypeObject *type)
                 const int index = m_baseObject->indexOfProperty(name);
                 if (index == -1)
                     addProperty(name, value);
-            } else if (Py_TYPE(value)->tp_call != nullptr) {
+            } else if (PepType_GetSlot(Py_TYPE(value), Py_tp_call) != nullptr) {
                 // PYSIDE-198: PyFunction_Check does not work with Nuitka.
                 // Register slots.
                 if (PyObject_HasAttr(value, slotAttrName)) {
diff --git a/sources/pyside6/libpyside/globalreceiverv2.cpp b/sources/pyside6/libpyside/globalreceiverv2.cpp
index 09385645d..5fcf224ea 100644
--- a/sources/pyside6/libpyside/globalreceiverv2.cpp
+++ b/sources/pyside6/libpyside/globalreceiverv2.cpp
@@ -9,6 +9,7 @@
 
 #include <autodecref.h>
 #include <gilstate.h>
+#include <pep384ext.h>
 
 #include <QtCore/QMetaMethod>
 #include <QtCore/QSet>
@@ -135,7 +136,7 @@ PyObject *DynamicSlotDataV2::callback()
 
     //create a callback based on method data
     if (m_isMethod)
-        callback = Py_TYPE(m_callback)->tp_descr_get(m_callback, m_pythonSelf, nullptr);
+        callback = PepExt_Type_CallDescrGet(m_callback, m_pythonSelf, nullptr);
     else
         Py_INCREF(callback);
 
diff --git a/sources/pyside6/libpyside/pysideclassdecorator_p.h b/sources/pyside6/libpyside/pysideclassdecorator_p.h
index d4e21a5b4..6068f6a2e 100644
--- a/sources/pyside6/libpyside/pysideclassdecorator_p.h
+++ b/sources/pyside6/libpyside/pysideclassdecorator_p.h
@@ -7,6 +7,7 @@
 #include <pysidemacros.h>
 
 #include <sbkpython.h>
+#include <pep384ext.h>
 
 #include <QtCore/QByteArray>
 
@@ -119,7 +120,7 @@ struct Methods
 {
     static PyObject *tp_new(PyTypeObject *subtype)
     {
-        auto *result = reinterpret_cast<PySideClassDecorator *>(subtype->tp_alloc(subtype, 0));
+        auto *result = PepExt_TypeCallAlloc<PySideClassDecorator>(subtype, 0);
         result->d = new DecoratorPrivate;
         return reinterpret_cast<PyObject *>(result);
     }
@@ -129,7 +130,7 @@ struct Methods
         auto pySelf = reinterpret_cast<PyObject *>(self);
         auto decorator = reinterpret_cast<PySideClassDecorator *>(self);
         delete decorator->d;
-        Py_TYPE(pySelf)->tp_base->tp_free(self);
+        PepExt_TypeCallFree(Py_TYPE(pySelf)->tp_base, self);
     }
 
     static PyObject *tp_call(PyObject *self, PyObject *args, PyObject *kwds)
diff --git a/sources/pyside6/libpyside/pysideproperty.cpp b/sources/pyside6/libpyside/pysideproperty.cpp
index 2648ca43c..457415479 100644
--- a/sources/pyside6/libpyside/pysideproperty.cpp
+++ b/sources/pyside6/libpyside/pysideproperty.cpp
@@ -8,6 +8,7 @@
 #include "pysidesignal_p.h"
 
 #include <shiboken.h>
+#include <pep384ext.h>
 #include <signature.h>
 
 using namespace Shiboken;
@@ -179,7 +180,7 @@ void PySidePropertyPrivate::metaCall(PyObject *source, QMetaObject::Call call, v
 
 static PyObject *qpropertyTpNew(PyTypeObject *subtype, PyObject * /* args */, PyObject * /* kwds */)
 {
-    auto *me = reinterpret_cast<PySideProperty *>(subtype->tp_alloc(subtype, 0));
+    auto *me = PepExt_TypeCallAlloc<PySideProperty>(subtype, 0);
     me->d = new PySidePropertyPrivate;
     return reinterpret_cast<PyObject *>(me);
 }
@@ -258,7 +259,7 @@ static void qpropertyDeAlloc(PyObject *self)
         Py_DECREF(Py_TYPE(self));
     }
     PyObject_GC_UnTrack(self);
-    Py_TYPE(self)->tp_free(self);
+    PepExt_TypeCallFree(self);
 }
 
 // Create a copy of the property to prevent the @property.setter from modifying
diff --git a/sources/pyside6/libpyside/pysidesignal.cpp b/sources/pyside6/libpyside/pysidesignal.cpp
index 0c6a23245..150dd500e 100644
--- a/sources/pyside6/libpyside/pysidesignal.cpp
+++ b/sources/pyside6/libpyside/pysidesignal.cpp
@@ -18,6 +18,7 @@
 #include <QtCore/QObject>
 #include <QtCore/QMetaMethod>
 #include <QtCore/QMetaObject>
+#include <pep384ext.h>
 #include <signature.h>
 
 #include <algorithm>
@@ -298,7 +299,7 @@ static void signalFree(void *vself)
     Py_XDECREF(self->homonymousMethod);
     self->homonymousMethod = nullptr;
 
-    Py_TYPE(pySelf)->tp_base->tp_free(self);
+    PepExt_TypeCallFree(Py_TYPE(pySelf)->tp_base, self);
 }
 
 static PyObject *signalGetItem(PyObject *obSelf, PyObject *key)
@@ -368,7 +369,7 @@ static void signalInstanceFree(void *vself)
         self->d = nullptr;
     }
     self->deleted = true;
-    Py_TYPE(pySelf)->tp_base->tp_free(self);
+    PepExt_TypeCallFree(Py_TYPE(pySelf)->tp_base, self);
 }
 
 // PYSIDE-1523: PyFunction_Check is not accepting compiled functions and
@@ -754,18 +755,16 @@ static PyObject *signalCall(PyObject *self, PyObject *args, PyObject *kw)
         return nullptr;
     }
 
-    descrgetfunc getDescriptor = Py_TYPE(signal->homonymousMethod)->tp_descr_get;
-
     // Check if there exists a method with the same name as the signal, which is also a static
     // method in C++ land.
-    Shiboken::AutoDecRef homonymousMethod(getDescriptor(signal->homonymousMethod,
-                                                        nullptr, nullptr));
+    Shiboken::AutoDecRef homonymousMethod(PepExt_Type_CallDescrGet(signal->homonymousMethod,
+                                                                   nullptr, nullptr));
     if (PyCFunction_Check(homonymousMethod.object())
             && (PyCFunction_GET_FLAGS(homonymousMethod.object()) & METH_STATIC))
         return PyObject_Call(homonymousMethod, args, kw);
 
     // Assumes homonymousMethod is not a static method.
-    ternaryfunc callFunc = Py_TYPE(signal->homonymousMethod)->tp_call;
+    ternaryfunc callFunc = PepExt_Type_GetCallSlot(Py_TYPE(signal->homonymousMethod));
     return callFunc(homonymousMethod, args, kw);
 }
 
@@ -822,8 +821,8 @@ static PyObject *signalInstanceCall(PyObject *self, PyObject *args, PyObject *kw
         return nullptr;
     }
 
-    descrgetfunc getDescriptor = Py_TYPE(hom)->tp_descr_get;
-    Shiboken::AutoDecRef homonymousMethod(getDescriptor(hom, PySideSignal->d->source, nullptr));
+    Shiboken::AutoDecRef homonymousMethod(PepExt_Type_CallDescrGet(hom, PySideSignal->d->source,
+                                                                   nullptr));
     return PyObject_Call(homonymousMethod, args, kw);
 }
 
diff --git a/sources/pyside6/libpysideqml/pysideqmllistproperty.cpp b/sources/pyside6/libpysideqml/pysideqmllistproperty.cpp
index a6f9f0193..97d6ce91b 100644
--- a/sources/pyside6/libpysideqml/pysideqmllistproperty.cpp
+++ b/sources/pyside6/libpysideqml/pysideqmllistproperty.cpp
@@ -5,6 +5,7 @@
 #include "pysideqmlregistertype_p.h"
 
 #include <shiboken.h>
+#include <pep384ext.h>
 #include <signature.h>
 
 #include <pysideproperty.h>
@@ -33,7 +34,7 @@ extern "C"
 
 static PyObject *propList_tp_new(PyTypeObject *subtype, PyObject * /* args */, PyObject * /* kwds */)
 {
-    PySideProperty *me = reinterpret_cast<PySideProperty *>(subtype->tp_alloc(subtype, 0));
+    auto *me = PepExt_TypeCallAlloc<PySideProperty>(subtype, 0);
     me->d = new QmlListPropertyPrivate;
     return reinterpret_cast<PyObject *>(me);
 }
diff --git a/sources/shiboken6/libshiboken/CMakeLists.txt b/sources/shiboken6/libshiboken/CMakeLists.txt
index 4638ca6f9..7a3c7d633 100644
--- a/sources/shiboken6/libshiboken/CMakeLists.txt
+++ b/sources/shiboken6/libshiboken/CMakeLists.txt
@@ -180,6 +180,7 @@ install(FILES
         sbkpython.h
         sbkwindows.h
         pep384impl.h
+        pep384ext.h
         voidptr.h
         bufferprocs_py37.h
         "${CMAKE_CURRENT_BINARY_DIR}/sbkversion.h"
diff --git a/sources/shiboken6/libshiboken/basewrapper.cpp b/sources/shiboken6/libshiboken/basewrapper.cpp
index 9a7d1d62d..bef687e41 100644
--- a/sources/shiboken6/libshiboken/basewrapper.cpp
+++ b/sources/shiboken6/libshiboken/basewrapper.cpp
@@ -5,6 +5,7 @@
 #include "basewrapper_p.h"
 #include "bindingmanager.h"
 #include "helper.h"
+#include "pep384ext.h"
 #include "sbkconverter.h"
 #include "sbkenum.h"
 #include "sbkerrors.h"
@@ -55,7 +56,7 @@ void Sbk_object_dealloc(PyObject *self)
         // This was not needed before Python 3.8 (Python issue 35810)
         Py_DECREF(Py_TYPE(self));
     }
-    Py_TYPE(self)->tp_free(self);
+    PepExt_TypeCallFree(self);
 }
 
 static void SbkObjectType_tp_dealloc(PyTypeObject *pyType);
@@ -522,7 +523,7 @@ static PyTypeObject *SbkObjectType_tp_new(PyTypeObject *metatype, PyObject *args
 
     for (int i=0, i_max=PyTuple_GET_SIZE(pyBases); i < i_max; i++) {
         PyObject *baseType = PyTuple_GET_ITEM(pyBases, i);
-        if (reinterpret_cast<PyTypeObject *>(baseType)->tp_new == SbkDummyNew) {
+        if (PepExt_Type_GetNewSlot(reinterpret_cast<PyTypeObject *>(baseType)) == SbkDummyNew) {
             // PYSIDE-595: A base class does not allow inheritance.
             return reinterpret_cast<PyTypeObject *>(SbkDummyNew(metatype, args, kwds));
         }
@@ -1645,7 +1646,7 @@ void deallocData(SbkObject *self, bool cleanup)
     }
     delete self->d; // PYSIDE-205: always delete d.
     Py_XDECREF(self->ob_dict);
-    Py_TYPE(self)->tp_free(self);
+    PepExt_TypeCallFree(reinterpret_cast<PyObject *>(self));
 }
 
 void setTypeUserData(SbkObject *wrapper, void *userData, DeleteUserDataFunc d_func)
diff --git a/sources/shiboken6/libshiboken/pep384ext.h b/sources/shiboken6/libshiboken/pep384ext.h
new file mode 100644
index 000000000..021c53d16
--- /dev/null
+++ b/sources/shiboken6/libshiboken/pep384ext.h
@@ -0,0 +1,89 @@
+// Copyright (C) 2024 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+#ifndef PEP384EXT_H
+#define PEP384EXT_H
+
+#include "pep384impl.h"
+
+/// Returns the allocator slot of the PyTypeObject.
+inline allocfunc PepExt_Type_GetAllocSlot(PyTypeObject *t)
+{
+    return reinterpret_cast<allocfunc>(PepType_GetSlot(t, Py_tp_alloc));
+}
+
+/// Invokes the allocator slot of the PyTypeObject.
+template <class Type>
+inline Type *PepExt_TypeCallAlloc(PyTypeObject *t, Py_ssize_t nitems)
+{
+    PyObject *result = PepExt_Type_GetAllocSlot(t)(t, nitems);
+    return reinterpret_cast<Type *>(result);
+}
+
+/// Returns the getattro slot of the PyTypeObject.
+inline getattrofunc PepExt_Type_GetGetAttroSlot(PyTypeObject *t)
+{
+    return reinterpret_cast<getattrofunc>(PepType_GetSlot(t, Py_tp_getattro));
+}
+
+/// Returns the setattro slot of the PyTypeObject.
+inline setattrofunc PepExt_Type_GetSetAttroSlot(PyTypeObject *t)
+{
+    return reinterpret_cast<setattrofunc>(PepType_GetSlot(t, Py_tp_setattro));
+}
+
+/// Returns the descr_get slot of the PyTypeObject.
+inline descrgetfunc PepExt_Type_GetDescrGetSlot(PyTypeObject *t)
+{
+    return reinterpret_cast<descrgetfunc>(PepType_GetSlot(t, Py_tp_descr_get));
+}
+
+/// Invokes the descr_get slot of the PyTypeObject.
+inline PyObject *PepExt_Type_CallDescrGet(PyObject *self, PyObject *obj, PyObject *type)
+{
+    return PepExt_Type_GetDescrGetSlot(Py_TYPE(self))(self, obj, type);
+}
+
+/// Returns the descr_set slot of the PyTypeObject.
+inline descrsetfunc PepExt_Type_GetDescrSetSlot(PyTypeObject *t)
+{
+    return reinterpret_cast<descrsetfunc>(PepType_GetSlot(t, Py_tp_descr_set));
+}
+
+/// Returns the call slot of the PyTypeObject.
+inline ternaryfunc PepExt_Type_GetCallSlot(PyTypeObject *t)
+{
+    return reinterpret_cast<ternaryfunc>(PepType_GetSlot(t, Py_tp_call));
+}
+
+/// Returns the new slot of the PyTypeObject.
+inline newfunc PepExt_Type_GetNewSlot(PyTypeObject *t)
+{
+    return reinterpret_cast<newfunc>(PepType_GetSlot(t, Py_tp_new));
+}
+
+/// Returns the init slot of the PyTypeObject.
+inline initproc PepExt_Type_GetInitSlot(PyTypeObject *t)
+{
+    return reinterpret_cast<initproc>(PepType_GetSlot(t, Py_tp_init));
+}
+
+/// Returns the free slot of the PyTypeObject.
+inline freefunc PepExt_Type_GetFreeSlot(PyTypeObject *t)
+{
+    return reinterpret_cast<freefunc>(PepType_GetSlot(t, Py_tp_free));
+}
+
+/// Invokes the free slot of the PyTypeObject.
+inline void PepExt_TypeCallFree(PyTypeObject *t, void *object)
+{
+    PepExt_Type_GetFreeSlot(t)(object);
+}
+
+/// Invokes the free slot of the PyTypeObject.
+inline void PepExt_TypeCallFree(PyObject *object)
+{
+    PepExt_Type_GetFreeSlot(Py_TYPE(object))(object);
+}
+
+#endif // PEP384EXT_H
diff --git a/sources/shiboken6/libshiboken/sbkcontainer.h b/sources/shiboken6/libshiboken/sbkcontainer.h
index 96faf95ee..240c772a9 100644
--- a/sources/shiboken6/libshiboken/sbkcontainer.h
+++ b/sources/shiboken6/libshiboken/sbkcontainer.h
@@ -63,7 +63,8 @@ public:
 
     static PyObject *tpNew(PyTypeObject *subtype, PyObject * /* args */, PyObject * /* kwds */)
     {
-        auto *me = reinterpret_cast<ShibokenContainer *>(subtype->tp_alloc(subtype, 0));
+        allocfunc allocFunc = reinterpret_cast<allocfunc>(PepType_GetSlot(subtype, Py_tp_alloc));
+        auto *me = reinterpret_cast<ShibokenContainer *>(allocFunc(subtype, 0));
         auto *d = new ShibokenSequenceContainerPrivate;
         d->m_list = new SequenceContainer;
         d->m_ownsList = true;
@@ -91,7 +92,9 @@ public:
         if (d->m_ownsList)
             delete d->m_list;
         delete d;
-        Py_TYPE(pySelf)->tp_base->tp_free(self);
+        auto freeFunc = reinterpret_cast<freefunc>(PepType_GetSlot(Py_TYPE(pySelf)->tp_base,
+                                                                   Py_tp_free));
+        freeFunc(self);
     }
 
     static Py_ssize_t sqLen(PyObject *self)
diff --git a/sources/shiboken6/libshiboken/sbkfeature_base.cpp b/sources/shiboken6/libshiboken/sbkfeature_base.cpp
index 906df8e19..1bd4d6851 100644
--- a/sources/shiboken6/libshiboken/sbkfeature_base.cpp
+++ b/sources/shiboken6/libshiboken/sbkfeature_base.cpp
@@ -4,6 +4,7 @@
 #include "basewrapper.h"
 #include "basewrapper_p.h"
 #include "autodecref.h"
+#include "pep384ext.h"
 #include "sbkenum.h"
 #include "sbkstring.h"
 #include "sbkstaticstrings.h"
@@ -300,7 +301,7 @@ PyObject *mangled_type_getattro(PyTypeObject *type, PyObject *name)
      * with the complex `tp_getattro` of `QObject` and other instances.
      * What we change here is the meta class of `QObject`.
      */
-    static getattrofunc const type_getattro = PyType_Type.tp_getattro;
+    static getattrofunc const type_getattro = PepExt_Type_GetGetAttroSlot(&PyType_Type);
     static PyObject *const ignAttr1 = PyName::qtStaticMetaObject();
     static PyObject *const ignAttr2 = PyMagicName::get();
     static PyTypeObject *const EnumMeta = getPyEnumMeta();
diff --git a/sources/shiboken6/libshiboken/voidptr.cpp b/sources/shiboken6/libshiboken/voidptr.cpp
index ed4f88ad1..7045b08b1 100644
--- a/sources/shiboken6/libshiboken/voidptr.cpp
+++ b/sources/shiboken6/libshiboken/voidptr.cpp
@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
 #include "voidptr.h"
+#include "pep384ext.h"
 #include "sbkconverter.h"
 #include "basewrapper.h"
 #include "basewrapper_p.h"
@@ -24,8 +25,7 @@ PyObject *SbkVoidPtrObject_new(PyTypeObject *type, PyObject * /* args */, PyObje
     // like this, actual call forgotten:
     //    SbkVoidPtrObject *self =
     //        reinterpret_cast<SbkVoidPtrObject *>(type->tp_alloc);
-    PyObject *ob = type->tp_alloc(type, 0);
-    auto *self = reinterpret_cast<SbkVoidPtrObject *>(ob);
+    auto *self = PepExt_TypeCallAlloc<SbkVoidPtrObject>(type, 0);
 
     if (self != nullptr) {
         self->cptr = nullptr;