python · serhiy-storchaka · Mar 30, 2026 · Mar 26, 2026
@@ -328,14 +328,14 @@ def __ior__(self, other):
        return self

    def __or__(self, other):
-        if not isinstance(other, dict):
+        if not isinstance(other, (dict, frozendict)):
            return NotImplemented
        new = self.__class__(self)
        new.update(other)
        return new

    def __ror__(self, other):
-        if not isinstance(other, dict):
+        if not isinstance(other, (dict, frozendict)):
            return NotImplemented
        new = self.__class__(other)
        new.update(self)

diff --git a/Lib/test/test_ordered_dict.py b/Lib/test/test_ordered_dict.py
@@ -698,6 +698,7 @@ def test_merge_operator(self):
        d |= list(b.items())
        expected = OrderedDict({0: 0, 1: 1, 2: 2, 3: 3})
        self.assertEqual(a | dict(b), expected)
+        self.assertEqual(a | frozendict(b), expected)
        self.assertEqual(a | b, expected)
        self.assertEqual(c, expected)
        self.assertEqual(d, expected)
@@ -706,12 +707,17 @@ def test_merge_operator(self):
        c |= a
        expected = OrderedDict({1: 1, 2: 1, 3: 3, 0: 0})
        self.assertEqual(dict(b) | a, expected)
+        self.assertEqual(frozendict(b) | a, expected)
+        self.assertEqual(a.__ror__(frozendict(b)), expected)
        self.assertEqual(b | a, expected)
        self.assertEqual(c, expected)

        self.assertIs(type(a | b), OrderedDict)
        self.assertIs(type(dict(a) | b), OrderedDict)
+        self.assertIs(type(frozendict(a) | b), frozendict)
+        self.assertIs(type(b.__ror__(frozendict(a))), OrderedDict)
        self.assertIs(type(a | dict(b)), OrderedDict)
+        self.assertIs(type(a | frozendict(b)), OrderedDict)

        expected = a.copy()
        a |= ()

diff --git a/Misc/NEWS.d/next/Library/2026-03-26-14-51-55.gh-issue-145056.QS-6l1.rst b/Misc/NEWS.d/next/Library/2026-03-26-14-51-55.gh-issue-145056.QS-6l1.rst
@@ -0,0 +1 @@
+Fix merging of :class:`collections.OrderedDict` and :class:`frozendict`.
diff --git a/Objects/odictobject.c b/Objects/odictobject.c
@@ -906,7 +906,7 @@ odict_or(PyObject *left, PyObject *right)
        type = Py_TYPE(right);
        other = left;
    }
-    if (!PyDict_Check(other)) {
+    if (!PyAnyDict_Check(other)) {
        Py_RETURN_NOTIMPLEMENTED;
    }
    PyObject *new = PyObject_CallOneArg((PyObject*)type, left);
@@ -2271,7 +2271,7 @@ static int
 mutablemapping_update_arg(PyObject *self, PyObject *arg)
 {
    int res = 0;
-    if (PyDict_CheckExact(arg)) {
+    if (PyAnyDict_CheckExact(arg)) {
        PyObject *items = PyDict_Items(arg);
        if (items == NULL) {
            return -1;
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		Fix merging of :class:`collections.OrderedDict` and :class:`frozendict`.