From: Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com>
Date: Wed, 9 Sep 2020 18:15:49 +0000 (-0700)
Subject: [3.8] [3.9] bpo-41688: Document bug in **= dispatching in the language data… (GH... 
X-Git-Tag: v3.8.6~33
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=4c4c354de2c9a290afbd4e5fcba07e3696ca0396;p=thirdparty%2FPython%2Fcpython.git

[3.8] [3.9] bpo-41688: Document bug in **= dispatching in the language data… (GH-22172) (GH-22175)



(cherry picked from commit 46bc21e1780016aaacd34e472f838dc792fb674c)


Co-authored-by: Ammar Askar <ammar@ammaraskar.com>

Automerge-Triggered-By: @brettcannon
---

diff --git a/Doc/reference/datamodel.rst b/Doc/reference/datamodel.rst
index c1262cdb9c10..3f0538586241 100644
--- a/Doc/reference/datamodel.rst
+++ b/Doc/reference/datamodel.rst
@@ -2404,6 +2404,13 @@ 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)