bpo-31586: Use _count_element fast path for real dicts.

diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
index e78399ddefa43c0ee7a7eef987520cd2fbdeb33a..b6cceee27f5627ca7bf33d040b580c9964014195 100644 (file)
--- a/Modules/_collectionsmodule.c
+++ b/Modules/_collectionsmodule.c
@@ -2277,7 +2277,9 @@ _count_elements(PyObject *self, PyObject *args)
     dict_setitem = _PyType_LookupId(&PyDict_Type, &PyId___setitem__);
 
     if (mapping_get != NULL && mapping_get == dict_get &&
-        mapping_setitem != NULL && mapping_setitem == dict_setitem) {
+        mapping_setitem != NULL && mapping_setitem == dict_setitem &&
+        PyDict_Check(mapping))
+    {
         while (1) {
             /* Fast path advantages:
                    1. Eliminate double hashing