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bpo-39573: Py_TYPE becomes a static inline function (GH-26493)
Convert the Py_TYPE() and Py_SIZE() macros to static inline functions. The Py_SET_TYPE() and Py_SET_SIZE() functions must now be used to set an object type and size.
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Lines changed: 52 additions & 9 deletions

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‎Doc/c-api/structures.rst‎

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@@ -99,7 +99,10 @@ the definition of all other Python objects.
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Return a :term:`borrowed reference`.
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The :c:func:`Py_SET_TYPE` function must be used to set an object type.
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Use the :c:func:`Py_SET_TYPE` function to set an object type.
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.. versionchanged:: 3.11
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:c:func:`Py_TYPE()` is changed to an inline static function.
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.. c:function:: int Py_IS_TYPE(PyObject *o, PyTypeObject *type)
@@ -121,9 +124,10 @@ the definition of all other Python objects.
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Get the reference count of the Python object *o*.
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Use the :c:func:`Py_SET_REFCNT()` function to set an object reference count.
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.. versionchanged:: 3.10
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:c:func:`Py_REFCNT()` is changed to the inline static function.
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Use :c:func:`Py_SET_REFCNT()` to set an object reference count.
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.. c:function:: void Py_SET_REFCNT(PyObject *o, Py_ssize_t refcnt)
@@ -137,7 +141,10 @@ the definition of all other Python objects.
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Get the size of the Python object *o*.
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The :c:func:`Py_SET_SIZE` function must be used to set an object size.
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Use the :c:func:`Py_SET_SIZE` function to set an object size.
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.. versionchanged:: 3.11
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:c:func:`Py_SIZE()` is changed to an inline static function.
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.. c:function:: void Py_SET_SIZE(PyVarObject *o, Py_ssize_t size)

‎Doc/whatsnew/3.11.rst‎

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@@ -149,6 +149,34 @@ Porting to Python 3.11
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(:c:member:`PyTypeObject.tp_traverse`).
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(Contributed by Victor Stinner in :issue:`44263`.)
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* Since :c:func:`Py_TYPE()` is changed to a inline static function,
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``Py_TYPE(obj) = new_type`` must be replaced with
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``Py_SET_TYPE(obj, new_type)``: see the :c:func:`Py_SET_TYPE()` function
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(available since Python 3.9). For backward compatibility, this macro can be
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used::
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#if PY_VERSION_HEX < 0x030900A4 && !defined(Py_SET_TYPE)
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static inline void _Py_SET_TYPE(PyObject *ob, PyTypeObject *type)
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{ ob->ob_type = type; }
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#define Py_SET_TYPE(ob, type) _Py_SET_TYPE(_PyObject_CAST(ob), type)
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#endif
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(Contributed by Victor Stinner in :issue:`39573`.)
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* Since :c:func:`Py_SIZE()` is changed to a inline static function,
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``Py_SIZE(obj) = new_size`` must be replaced with
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``Py_SET_SIZE(obj, new_size)``: see the :c:func:`Py_SET_SIZE()` function
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(available since Python 3.9). For backward compatibility, this macro can be
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used::
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#if PY_VERSION_HEX < 0x030900A4 && !defined(Py_SET_SIZE)
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static inline void _Py_SET_SIZE(PyVarObject *ob, Py_ssize_t size)
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{ ob->ob_size = size; }
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#define Py_SET_SIZE(ob, size) _Py_SET_SIZE((PyVarObject*)(ob), size)
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#endif
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(Contributed by Victor Stinner in :issue:`39573`.)
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Deprecated
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----------
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‎Include/object.h‎

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@@ -134,10 +134,16 @@ static inline Py_ssize_t _Py_REFCNT(const PyObject *ob) {
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// bpo-39573: The Py_SET_TYPE() function must be used to set an object type.
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#define Py_TYPE(ob) (_PyObject_CAST(ob)->ob_type)
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static inline PyTypeObject* _Py_TYPE(const PyObject *ob) {
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return ob->ob_type;
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}
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#define Py_TYPE(ob) _Py_TYPE(_PyObject_CAST_CONST(ob))
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// bpo-39573: The Py_SET_SIZE() function must be used to set an object size.
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#define Py_SIZE(ob) (_PyVarObject_CAST(ob)->ob_size)
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static inline Py_ssize_t _Py_SIZE(const PyVarObject *ob) {
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return ob->ob_size;
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}
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#define Py_SIZE(ob) _Py_SIZE(_PyVarObject_CAST_CONST(ob))
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static inline int _Py_IS_TYPE(const PyObject *ob, const PyTypeObject *type) {

‎Misc/NEWS.d/next/C API/2021-06-03-00-59-48.bpo-39573.-elHTJ.rst‎

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Convert the :c:func:`Py_TYPE` and :c:func:`Py_SIZE` macros to static inline
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functions. The :c:func:`Py_SET_TYPE` and :c:func:`Py_SET_SIZE` functions
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must now be used to set an object type and size. Patch by Victor Stinner.

‎Modules/_testcapimodule.c‎

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@@ -5423,10 +5423,9 @@ test_set_type_size(PyObject *self, PyObject *Py_UNUSED(ignored))
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assert(Py_TYPE(obj) == &PyList_Type);
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assert(Py_SIZE(obj) == 0);
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// bpo-39573: Check that Py_TYPE() and Py_SIZE() can be used
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// as l-values to set an object type and size.
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Py_TYPE(obj) = &PyList_Type;
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Py_SIZE(obj) = 0;
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// bpo-39573: Test Py_SET_TYPE() and Py_SET_SIZE() functions.
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Py_SET_TYPE(obj, &PyList_Type);
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Py_SET_SIZE(obj, 0);
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Py_DECREF(obj);
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Py_RETURN_NONE;

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