diff --git a/Lib/test/test_dict.py b/Lib/test/test_dict.py index 21f8bb11071c90..bfc9e7a07a0c25 100644 --- a/Lib/test/test_dict.py +++ b/Lib/test/test_dict.py @@ -1787,6 +1787,23 @@ def test_hash(self): with self.assertRaisesRegex(TypeError, "unhashable type: 'list'"): hash(fd) + def test_fromkeys(self): + self.assertEqual(frozendict.fromkeys('abc'), + frozendict(a=None, b=None, c=None)) + + # frozendict.fromkeys() must not call subclass constructor + class FrozenDictSubclass(frozendict): + def __new__(self): + raise ValueError("must not be called") + + fd = FrozenDictSubclass.fromkeys("abc") + self.assertEqual(fd, frozendict(a=None, b=None, c=None)) + self.assertEqual(type(fd), FrozenDictSubclass) + + fd = FrozenDictSubclass.fromkeys(frozendict(x=1)) + self.assertEqual(fd, frozendict(x=None)) + self.assertEqual(type(fd), FrozenDictSubclass) + if __name__ == "__main__": unittest.main() diff --git a/Objects/dictobject.c b/Objects/dictobject.c index 0959e2c78a3289..5df3817e3de3d0 100644 --- a/Objects/dictobject.c +++ b/Objects/dictobject.c @@ -3285,10 +3285,17 @@ _PyDict_FromKeys(PyObject *cls, PyObject *iterable, PyObject *value) PyObject *d; int status; - d = _PyObject_CallNoArgs(cls); - if (d == NULL) + if (PyObject_IsSubclass(cls, (PyObject*)&PyFrozenDict_Type)) { + // Never call frozendict subclass constructor which would call + // arbitrary Python code. + d = frozendict_new(_PyType_CAST(cls), NULL, NULL); + } + else { + d = _PyObject_CallNoArgs(cls); + } + if (d == NULL) { return NULL; - + } if (PyDict_CheckExact(d)) { if (PyDict_CheckExact(iterable)) { @@ -3359,7 +3366,7 @@ _PyDict_FromKeys(PyObject *cls, PyObject *iterable, PyObject *value) dict_iter_exit:; Py_END_CRITICAL_SECTION(); } - else if (PyFrozenDict_CheckExact(d)) { + else if (PyFrozenDict_Check(d)) { while ((key = PyIter_Next(it)) != NULL) { // anydict_setitem_take2 consumes a reference to key status = anydict_setitem_take2((PyDictObject *)d, @@ -7994,6 +8001,8 @@ frozendict_new(PyTypeObject *type, PyObject *args, PyObject *kwds) if (d == NULL) { return NULL; } + assert(Py_REFCNT(d) == 1); + PyFrozenDictObject *self = _PyFrozenDictObject_CAST(d); self->ma_hash = -1;