3 files changed, 29 insertions, 10 deletions
diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index 0f2a271..84cf482 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -1088,10 +1088,9 @@ dict_update_common(PyObject *self, PyObject *args, PyObject *kwds, char *methnam
 static PyObject *
 dict_update(PyObject *self, PyObject *args, PyObject *kwds)
 {
-	if (dict_update_common(self, args, kwds, "update") == -1)
-		return NULL;
-	Py_INCREF(Py_None);
-	return Py_None;
+	if (dict_update_common(self, args, kwds, "update") != -1)
+		Py_RETURN_NONE;
+	return NULL;
 }
 
 /* Update unconditionally replaces existing items.
@@ -1593,8 +1592,7 @@ static PyObject *
 dict_clear(register dictobject *mp)
 {
 	PyDict_Clear((PyObject *)mp);
-	Py_INCREF(Py_None);
-	return Py_None;
+	Py_RETURN_NONE;
 }
 
 static PyObject *
@@ -2050,7 +2048,9 @@ dictiter_dealloc(dictiterobject *di)
 static int
 dictiter_len(dictiterobject *di)
 {
-	return di->len;
+	if (di->di_dict != NULL && di->di_used == di->di_dict->ma_used)
+		return di->len;
+	return 0;
 }
 
 static PySequenceMethods dictiter_as_sequence = {
diff --git a/Objects/enumobject.c b/Objects/enumobject.c
index 28719a9..549fc9f 100644
--- a/Objects/enumobject.c
+++ b/Objects/enumobject.c
@@ -225,6 +225,9 @@ reversed_next(reversedobject *ro)
 			ro->index--;
 			return item;
 		}
+		if (PyErr_ExceptionMatches(PyExc_IndexError) ||
+		    PyErr_ExceptionMatches(PyExc_StopIteration))
+			PyErr_Clear();
 	}
 	ro->index = -1;
 	if (ro->seq != NULL) {
@@ -242,7 +245,15 @@ PyDoc_STRVAR(reversed_doc,
 static int
 reversed_len(reversedobject *ro)
 {
-	return ro->index + 1;
+	int position, seqsize;
+
+	if (ro->seq == NULL)
+		return 0;
+	seqsize = PySequence_Size(ro->seq);
+	if (seqsize == -1)
+		return -1;
+	position = ro->index + 1;
+	return (seqsize < position)  ?  0  :  position;
 }
 
 static PySequenceMethods reversed_as_sequence = {
diff --git a/Objects/iterobject.c b/Objects/iterobject.c
index a407dd5..25e4e11 100644
--- a/Objects/iterobject.c
+++ b/Objects/iterobject.c
@@ -74,8 +74,16 @@ iter_iternext(PyObject *iterator)
 static int
 iter_len(seqiterobject *it)
 {
-	if (it->it_seq)
-		return PyObject_Size(it->it_seq) - it->it_index;
+	int seqsize, len;
+
+	if (it->it_seq) {
+		seqsize = PySequence_Size(it->it_seq);
+		if (seqsize == -1)
+			return -1;
+		len = seqsize - it->it_index;
+		if (len >= 0)
+			return len;
+	}
 	return 0;
 }