bpo-38210: Remove intersection operation with empty set

Lib/test/test_dictviews.py

@@ -158,6 +158,12 @@ def intersection(self, other):
         self.assertTrue(de.keys().isdisjoint(de.keys()))
         self.assertTrue(de.keys().isdisjoint([1]))
 
+    def test_keys_set_operations_with_iterator(self):
+        origin = {1: 2, 3: 4}
+        self.assertEqual((origin.keys() & iter([1, 2])), {1})
+        self.assertEqual((origin.keys() | iter([1, 2])), {1, 2, 3})
+        self.assertEqual((origin.keys() ^ iter([1, 2])), {2, 3})
+
     def test_items_set_operations(self):
         d1 = {'a': 1, 'b': 2}
         d2 = {'a': 2, 'b': 2}

Misc/NEWS.d/next/Core and Builtins/2019-10-06-15-01-57.bpo-38210.Xgc6F_.rst

@@ -0,0 +1,2 @@
+Remove unecessary intersection and update set operation in dictview with
+empty set. (Contributed by Dong-hee Na in :issue:`38210`.)

Objects/dictobject.c

@@ -4225,14 +4225,6 @@ _PyDictView_Intersect(PyObject* self, PyObject *other)
 
     it = PyObject_GetIter(other);
 
-    _Py_IDENTIFIER(intersection_update);
-    tmp = _PyObject_CallMethodIdOneArg(result, &PyId_intersection_update, other);
-    if (tmp == NULL) {
-        Py_DECREF(result);
-        return NULL;
-    }
-    Py_DECREF(tmp);
-
     if (PyDictKeys_Check(self)) {
         dict_contains = dictkeys_contains;
     }