1 files changed, 16 insertions, 10 deletions

diff --git a/Objects/listobject.c b/Objects/listobject.c
index 19967ca..d688179 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -2324,7 +2324,7 @@ list_sizeof(PyListObject *self)
 {
     Py_ssize_t res;
 
-    res = sizeof(PyListObject) + self->allocated * sizeof(void*);
+    res = _PyObject_SIZE(Py_TYPE(self)) + self->allocated * sizeof(void*);
     return PyLong_FromSsize_t(res);
 }
 
@@ -2447,7 +2447,7 @@ list_subscript(PyListObject* self, PyObject* item)
     }
     else {
         PyErr_Format(PyExc_TypeError,
-                     "list indices must be integers, not %.200s",
+                     "list indices must be integers or slices, not %.200s",
                      item->ob_type->tp_name);
         return NULL;
     }
@@ -2611,7 +2611,7 @@ list_ass_subscript(PyListObject* self, PyObject* item, PyObject* value)
     }
     else {
         PyErr_Format(PyExc_TypeError,
-                     "list indices must be integers, not %.200s",
+                     "list indices must be integers or slices, not %.200s",
                      item->ob_type->tp_name);
         return -1;
     }
@@ -2782,8 +2782,8 @@ listiter_next(listiterobject *it)
         return item;
     }
 
-    Py_DECREF(seq);
     it->it_seq = NULL;
+    Py_DECREF(seq);
     return NULL;
 }
 
@@ -2912,9 +2912,17 @@ static PyObject *
 listreviter_next(listreviterobject *it)
 {
     PyObject *item;
-    Py_ssize_t index = it->it_index;
-    PyListObject *seq = it->it_seq;
+    Py_ssize_t index;
+    PyListObject *seq;
+
+    assert(it != NULL);
+    seq = it->it_seq;
+    if (seq == NULL) {
+        return NULL;
+    }
+    assert(PyList_Check(seq));
 
+    index = it->it_index;
     if (index>=0 && index < PyList_GET_SIZE(seq)) {
         item = PyList_GET_ITEM(seq, index);
         it->it_index--;
@@ -2922,10 +2930,8 @@ listreviter_next(listreviterobject *it)
         return item;
     }
     it->it_index = -1;
-    if (seq != NULL) {
-        it->it_seq = NULL;
-        Py_DECREF(seq);
-    }
+    it->it_seq = NULL;
+    Py_DECREF(seq);
     return NULL;
 }