diff --git a/Doc/whatsnew/3.14.rst b/Doc/whatsnew/3.14.rst index 13448d1fc07654..b20d75c1180713 100644 --- a/Doc/whatsnew/3.14.rst +++ b/Doc/whatsnew/3.14.rst @@ -1130,6 +1130,8 @@ typing For example, ``isinstance(int | str, typing.Union)`` will return ``True``; previously this raised :exc:`TypeError`. - The ``__args__`` attribute of :class:`typing.Union` objects is no longer writable. + - It is no longer possible to set arbitrary dunder attributes on :class:`typing.Union` + objects. (Contributed by Jelle Zijlstra in :gh:`105499`.)