gh-105927: Add PyWeakref_GetRef() function

Author: vstinner

Doc/c-api/weakref.rst

@@ -51,6 +51,15 @@ as much as it can.
    ``None``, or ``NULL``, this will return ``NULL`` and raise :exc:`TypeError`.
 
 
+.. c:function:: PyObject* PyWeakref_GetRef(PyObject *ref)
+
+   Return a :term:`strong reference` to the referenced object from a weak
+   reference, *ref*.  If the referent is no longer live, returns
+   ``NULL``.
+
+   .. versionadded:: 3.13
+
+
 .. c:function:: PyObject* PyWeakref_GetObject(PyObject *ref)
 
    Return the referenced object from a weak reference, *ref*.  If the referent is

Doc/data/refcounts.dat

@@ -2810,6 +2810,9 @@ PyWeakref_GET_OBJECT:PyObject*:ref:0:
 PyWeakref_GetObject:PyObject*::0:
 PyWeakref_GetObject:PyObject*:ref:0:
 
+PyWeakref_GetRef:PyObject*::+1:
+PyWeakref_GetRef:PyObject*:ref:0:
+
 PyWeakref_NewProxy:PyObject*::+1:
 PyWeakref_NewProxy:PyObject*:ob:0:
 PyWeakref_NewProxy:PyObject*:callback:0:

Doc/data/stable_abi.dat

@@ -431,6 +431,10 @@ New Features
   of a :term:`borrowed reference`.
   (Contributed by Victor Stinner in :gh:`105922`.)
 
+* Add :c:func:`PyWeakref_GetRef` function: similar to
+  :c:func:`PyWeakref_GetObject` but returns a :term:`strong reference`, or
+  ``NULL`` if the referent is no longer live.
+  (Contributed by Victor Stinner in :gh:`105927`.)
 
 Porting to Python 3.13
 ----------------------

Doc/whatsnew/3.13.rst

@@ -28,6 +28,7 @@ PyAPI_FUNC(PyObject *) PyWeakref_NewRef(PyObject *ob,
 PyAPI_FUNC(PyObject *) PyWeakref_NewProxy(PyObject *ob,
                                           PyObject *callback);
 PyAPI_FUNC(PyObject *) PyWeakref_GetObject(PyObject *ref);
+PyAPI_FUNC(PyObject *) PyWeakref_GetRef(PyObject *ref);
 
 
 #ifndef Py_LIMITED_API

Include/weakrefobject.h

@@ -0,0 +1,3 @@
+Add :c:func:`PyWeakref_GetRef` function: similar to
+:c:func:`PyWeakref_GetObject` but returns a :term:`strong reference`, or
+``NULL`` if the referent is no longer live. Patch by Victor Stinner.

Lib/test/test_stable_abi_ctypes.py

@@ -2430,3 +2430,5 @@
     added = '3.12'
 [function.PyImport_AddModuleRef]
     added = '3.13'
+[function.PyWeakref_GetRef]
+    added = '3.13'

Misc/NEWS.d/next/C API/2023-06-20-08-59-05.gh-issue-105927.DfGeEA.rst

@@ -150,12 +150,10 @@ _in_weak_set(PyObject *set, PyObject *obj)
 static PyObject *
 _destroy(PyObject *setweakref, PyObject *objweakref)
 {
-    PyObject *set;
-    set = PyWeakref_GET_OBJECT(setweakref);
-    if (set == Py_None) {
+    PyObject *set = PyWeakref_GetRef(setweakref);
+    if (set == NULL) {
         Py_RETURN_NONE;
     }
-    Py_INCREF(set);
     if (PySet_Discard(set, objweakref) < 0) {
         Py_DECREF(set);
         return NULL;

Misc/stable_abi.toml

@@ -894,6 +894,15 @@ PyWeakref_NewProxy(PyObject *ob, PyObject *callback)
 }
 
 
+PyObject*
+PyWeakref_GetRef(PyObject *ref)
+{
+    assert(ref != NULL);
+    assert(PyWeakref_Check(ref) != NULL);
+    return _PyWeakref_GET_REF(ref);
+}
+
+
 PyObject *
 PyWeakref_GetObject(PyObject *ref)
 {