[3.12] Document PyObject_SelfIter (GH-127861) (#127899)

Document PyObject_SelfIter (GH-127861)
(cherry picked from commit 58942a0)

Co-authored-by: Miro Hrončok <[email protected]>

Author: miss-islington

Doc/c-api/object.rst

@@ -410,6 +410,12 @@ Object Protocol
    iterated.
 
 
+.. c:function:: PyObject* PyObject_SelfIter(PyObject *obj)
+
+   This is equivalent to the Python ``__iter__(self): return self`` method.
+   It is intended for :term:`iterator` types, to be used in the :c:member:`PyTypeObject.tp_iter` slot.
+
+
 .. c:function:: PyObject* PyObject_GetAIter(PyObject *o)
 
    This is the equivalent to the Python expression ``aiter(o)``. Takes an

Doc/data/refcounts.dat

@@ -1818,6 +1818,9 @@ PyObject_RichCompareBool:PyObject*:o1:0:
 PyObject_RichCompareBool:PyObject*:o2:0:
 PyObject_RichCompareBool:int:opid::
 
+PyObject_SelfIter:PyObject*::+1:
+PyObject_SelfIter:PyObject*:obj:0:
+
 PyObject_SetAttr:int:::
 PyObject_SetAttr:PyObject*:o:0:
 PyObject_SetAttr:PyObject*:attr_name:0: