[3.5] bpo-30061: Check if PyObject_Size()/PySequence_Size()/PyMapping_Size() (GH-1096) (GH-1180) (#1182)

raised an error.

(cherry picked from commit bf623ae8843dc30b28c574bec8d29fc14be59d86)
(cherry picked from commit 680fea4067537a9b9c79aadd44a3a19e83cd2dbf)

1 files changed, 9 insertions, 3 deletions

diff --git a/Objects/setobject.c b/Objects/setobject.c
index 4ef692d..3dbdb4e 100644
--- a/Objects/setobject.c
+++ b/Objects/setobject.c
@@ -1498,15 +1498,21 @@ set_difference(PySetObject *so, PyObject *other)
 {
     PyObject *result;
     setentry *entry;
-    Py_ssize_t pos = 0;
+    Py_ssize_t pos = 0, other_size;
 
-    if (!PyAnySet_Check(other)  && !PyDict_CheckExact(other)) {
+    if (PyAnySet_Check(other)) {
+        other_size = PySet_GET_SIZE(other);
+    }
+    else if (PyDict_CheckExact(other)) {
+        other_size = PyDict_Size(other);
+    }
+    else {
         return set_copy_and_difference(so, other);
     }
 
     /* If len(so) much more than len(other), it's more efficient to simply copy
      * so and then iterate other looking for common elements. */
-    if ((PySet_GET_SIZE(so) >> 2) > PyObject_Size(other)) {
+    if ((PySet_GET_SIZE(so) >> 2) > other_size) {
         return set_copy_and_difference(so, other);
     }