diff options
Diffstat (limited to 'Include/weakrefobject.h')
| -rw-r--r-- | Include/weakrefobject.h | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/Include/weakrefobject.h b/Include/weakrefobject.h index 7258387..537e7eb 100644 --- a/Include/weakrefobject.h +++ b/Include/weakrefobject.h @@ -70,7 +70,17 @@ PyAPI_FUNC(Py_ssize_t) _PyWeakref_GetWeakrefCount(PyWeakReference *head); PyAPI_FUNC(void) _PyWeakref_ClearRef(PyWeakReference *self); #endif -#define PyWeakref_GET_OBJECT(ref) (((PyWeakReference *)(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 #16602. */ + +#define PyWeakref_GET_OBJECT(ref) \ + (Py_REFCNT(((PyWeakReference *)(ref))->wr_object) > 0 \ + ? ((PyWeakReference *)(ref))->wr_object \ + : Py_None) #ifdef __cplusplus |