From 42e3a8410b7dbc960b3b7c335f2bbb516c8caf6e Mon Sep 17 00:00:00 2001 From: Alex Waygood Date: Sun, 6 Apr 2025 16:51:05 +0100 Subject: gh-132139: 3.14 what's new: elaborate on why you can no longer set `Union` attributes (#132157) --- Doc/whatsnew/3.14.rst | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/Doc/whatsnew/3.14.rst b/Doc/whatsnew/3.14.rst index b20d75c..de76e25 100644 --- a/Doc/whatsnew/3.14.rst +++ b/Doc/whatsnew/3.14.rst @@ -1130,8 +1130,9 @@ 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. + - It is no longer possible to set any attributes on :class:`typing.Union` objects. + This only ever worked for dunder attributes on previous versions, was never + documented to work, and was subtly broken in many cases. (Contributed by Jelle Zijlstra in :gh:`105499`.) -- cgit v0.12