python · vstinner · Nov 11, 2020 · Nov 11, 2020
diff --git a/Include/cpython/object.h b/Include/cpython/object.h
@@ -244,6 +244,7 @@ struct _typeobject {
    struct PyMethodDef *tp_methods;
    struct PyMemberDef *tp_members;
    struct PyGetSetDef *tp_getset;
+    // Strong reference on a heap type, borrowed reference on a static type
    struct _typeobject *tp_base;
    PyObject *tp_dict;
    descrgetfunc tp_descr_get;

diff --git a/Objects/typeobject.c b/Objects/typeobject.c
@@ -5487,8 +5487,13 @@ PyType_Ready(PyTypeObject *type)
    /* Initialize tp_base (defaults to BaseObject unless that's us) */
    base = type->tp_base;
    if (base == NULL && type != &PyBaseObject_Type) {
-        base = type->tp_base = &PyBaseObject_Type;
-        Py_INCREF(base);
+        base = &PyBaseObject_Type;
+        if (type->tp_flags & Py_TPFLAGS_HEAPTYPE) {
+            type->tp_base = (PyTypeObject*)Py_NewRef((PyObject*)base);
+        }
+        else {
+            type->tp_base = base;
+        }
    }

    /* Now the only way base can still be NULL is if type is