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gh-89653: PEP 670: Convert PyWeakref_GET_OBJECT() to function (#91785)

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Convert the PyWeakref_GET_OBJECT() macro to a static inline function.
Add an assertion to check the argument with PyWeakref_Check(). Add a
macro converting the argument to PyObject* to prevent emitting new
compiler warning.
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Victor Stinner 2022-04-21 16:01:47 +02:00 • committed by GitHub
parent f2b4e458b3
commit 1a2b282f20
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1 changed files with 16 additions and 10 deletions
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26
Include/cpython/weakrefobject.h
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@ -36,13 +36,19 @@ PyAPI_FUNC(Py_ssize_t) _PyWeakref_GetWeakrefCount(PyWeakReference *head);
PyAPI_FUNC(void) _PyWeakref_ClearRef(PyWeakReference *self);
/* Explanation for the Py_REFCNT() check: when a weakref's target is part
of a long chain of deallocations which triggers the trashcan mechanism,
clearing the weakrefs can be delayed long after the target's refcount
has dropped to zero. In the meantime, code accessing the weakref will
be able to "see" the target object even though it is supposed to be
unreachable. See issue #16602. */
#define PyWeakref_GET_OBJECT(ref) \
(Py_REFCNT(((PyWeakReference *)(ref))->wr_object) > 0 \
? ((PyWeakReference *)(ref))->wr_object \
: Py_None)
static inline PyObject* PyWeakref_GET_OBJECT(PyObject *ref_obj) {
assert(PyWeakref_Check(ref_obj));
PyWeakReference *ref = (PyWeakReference *)ref_obj;
PyObject *obj = ref->wr_object;
// Explanation for the Py_REFCNT() check: when a weakref's target is part
// of a long chain of deallocations which triggers the trashcan mechanism,
// clearing the weakrefs can be delayed long after the target's refcount
// has dropped to zero. In the meantime, code accessing the weakref will
// be able to "see" the target object even though it is supposed to be
// unreachable. See issue gh-60806.
if (Py_REFCNT(obj) > 0) {
return obj;
}
return Py_None;
}
#define PyWeakref_GET_OBJECT(ref) PyWeakref_GET_OBJECT(_PyObject_CAST(ref))