From: Ammar Askar <ammar@ammaraskar.com>
Date: Wed, 9 Sep 2020 18:01:38 +0000 (-0400)
Subject: [3.9] bpo-41688: Document bug in **= dispatching in the language data… (GH-22172)
X-Git-Tag: v3.9.0rc2~24
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=46bc21e1780016aaacd34e472f838dc792fb674c;p=thirdparty%2FPython%2Fcpython.git

[3.9] bpo-41688: Document bug in **= dispatching in the language data… (GH-22172)



I tossed in a "This bug is fixed in Python 3.10" sentence but I'm not sure if that's appropriate to have here.
---

diff --git a/Doc/reference/datamodel.rst b/Doc/reference/datamodel.rst
index a817408c3b1e..fc304a191a31 100644
--- a/Doc/reference/datamodel.rst
+++ b/Doc/reference/datamodel.rst
@@ -2409,6 +2409,13 @@ left undefined.
    :ref:`faq-augmented-assignment-tuple-error`), but this behavior is in fact
    part of the data model.
 
+   .. note::
+
+      Due to a bug in the dispatching mechanism for ``**=``, a class that
+      defines :meth:`__ipow__` but returns ``NotImplemented`` would fail to
+      fall back to ``x.__pow__(y)`` and ``y.__rpow__(x)``. This bug is fixed
+      in Python 3.10.
+
 
 .. method:: object.__neg__(self)
             object.__pos__(self)