Use Py_TYPE(d) instead of cls_type to create the copy

Author: vstinner

Lib/test/test_dict.py

@@ -1944,32 +1944,32 @@ def __new__(self):
 
         fd = FrozenDictSubclass.fromkeys("abc")
         self.assertEqual(fd, frozendict(x=1, a=None, b=None, c=None))
-        self.assertEqual(type(fd), FrozenDictSubclass)
+        self.assertEqual(type(fd), frozendict)
         self.assertEqual(created, frozendict(x=1))
 
         fd = FrozenDictSubclass.fromkeys(frozendict(y=2))
         self.assertEqual(fd, frozendict(x=1, y=None))
-        self.assertEqual(type(fd), FrozenDictSubclass)
+        self.assertEqual(type(fd), frozendict)
         self.assertEqual(created, frozendict(x=1))
 
-        # Subclass which doesn't override the constructor
-        class FrozenDictSubclass2(frozendict):
-            pass
-
-        fd = FrozenDictSubclass2.fromkeys("abc")
-        self.assertEqual(fd, frozendict(a=None, b=None, c=None))
-        self.assertEqual(type(fd), FrozenDictSubclass2)
-
         # Dict subclass which overrides the constructor
         class DictSubclass(dict):
             def __new__(self):
                 return created
 
         fd = DictSubclass.fromkeys("abc")
         self.assertEqual(fd, frozendict(x=1, a=None, b=None, c=None))
-        self.assertEqual(type(fd), DictSubclass)
+        self.assertEqual(type(fd), frozendict)
         self.assertEqual(created, frozendict(x=1))
 
+        # Subclass which doesn't override the constructor
+        class FrozenDictSubclass2(frozendict):
+            pass
+
+        fd = FrozenDictSubclass2.fromkeys("abc")
+        self.assertEqual(fd, frozendict(a=None, b=None, c=None))
+        self.assertEqual(type(fd), FrozenDictSubclass2)
+
     def test_pickle(self):
         for proto in range(pickle.HIGHEST_PROTOCOL + 1):
             for fd in (

Objects/dictobject.c

@@ -3438,13 +3438,7 @@ _PyDict_FromKeys(PyObject *cls, PyObject *iterable, PyObject *value)
     // the GC, create a frozendict copy which is not tracked by the GC.
     if (PyFrozenDict_Check(d) && _PyObject_GC_IS_TRACKED(d)) {
         // Subclass-friendly copy
-        PyObject *copy;
-        if (PyObject_IsSubclass(cls, (PyObject*)&PyFrozenDict_Type)) {
-            copy = frozendict_new_untracked(cls_type);
-        }
-        else {
-            copy = dict_new_untracked(cls_type);
-        }
+        PyObject *copy = frozendict_new_untracked(Py_TYPE(d));
         if (copy == NULL) {
             goto Fail;
         }