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Revert "gh-98724: Fix Py_CLEAR() macro side effects" (#99737)

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Revert "gh-98724: Fix Py_CLEAR() macro side effects (#99100)"

This reverts commit c03e05c2e7.
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Victor Stinner 2022-11-24 22:17:33 +01:00 • committed by GitHub
parent 0da728387c
commit 3a803bcaac
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5 changed files with 29 additions and 172 deletions
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46
Doc/c-api/refcounting.rst
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@ -7,8 +7,8 @@
Reference Counting
******************
The functions and macros in this section are used for managing reference counts
of Python objects.
The macros in this section are used for managing reference counts of Python
objects.
.. c:function:: Py_ssize_t Py_REFCNT(PyObject *o)
@ -129,11 +129,6 @@ of Python objects.
It is a good idea to use this macro whenever decrementing the reference
count of an object that might be traversed during garbage collection.
.. versionchanged:: 3.12
The macro argument is now only evaluated once. If the argument has side
effects, these are no longer duplicated.
.. c:function:: void Py_IncRef(PyObject *o)
Increment the reference count for object *o*. A function version of :c:func:`Py_XINCREF`.
@ -144,40 +139,3 @@ of Python objects.
Decrement the reference count for object *o*. A function version of :c:func:`Py_XDECREF`.
It can be used for runtime dynamic embedding of Python.
.. c:macro:: Py_SETREF(dst, src)
Macro safely decrementing the `dst` reference count and setting `dst` to
`src`.
As in case of :c:func:`Py_CLEAR`, "the obvious" code can be deadly::
Py_DECREF(dst);
dst = src;
The safe way is::
Py_SETREF(dst, src);
That arranges to set `dst` to `src` _before_ decrementing reference count of
*dst* old value, so that any code triggered as a side-effect of `dst`
getting torn down no longer believes `dst` points to a valid object.
.. versionadded:: 3.6
.. versionchanged:: 3.12
The macro arguments are now only evaluated once. If an argument has side
effects, these are no longer duplicated.
.. c:macro:: Py_XSETREF(dst, src)
Variant of :c:macro:`Py_SETREF` macro that uses :c:func:`Py_XDECREF` instead
of :c:func:`Py_DECREF`.
.. versionadded:: 3.6
.. versionchanged:: 3.12
The macro arguments are now only evaluated once. If an argument has side
effects, these are no longer duplicated.

5
Doc/whatsnew/3.12.rst
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@ -822,11 +822,6 @@ Porting to Python 3.12
:class:`bytes` type is accepted for bytes strings.
(Contributed by Victor Stinner in :gh:`98393`.)
* The :c:macro:`Py_CLEAR`, :c:macro:`Py_SETREF` and :c:macro:`Py_XSETREF`
macros now only evaluate their argument once. If the argument has side
effects, these side effects are no longer duplicated.
(Contributed by Victor Stinner in :gh:`98724`.)
Deprecated
----------