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authorMiro HronĨok <miro@hroncok.cz>2020-05-04 19:02:00 (GMT)
committerGitHub <noreply@github.com>2020-05-04 19:02:00 (GMT)
commit18f1c60a1625d341a905c7e07367c32c08f222df (patch)
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bpo-40360: Add a What's New entry for lib2to3 pending deprecation (GH-19898)
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-rw-r--r--Doc/whatsnew/3.9.rst10
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diff --git a/Doc/whatsnew/3.9.rst b/Doc/whatsnew/3.9.rst
index cefaf57..11e577b 100644
--- a/Doc/whatsnew/3.9.rst
+++ b/Doc/whatsnew/3.9.rst
@@ -608,6 +608,16 @@ Deprecated
* Passing ``None`` as the first argument to the :func:`shlex.split` function
has been deprecated. (Contributed by Zackery Spytz in :issue:`33262`.)
+* The :mod:`lib2to3` module now emits a :exc:`PendingDeprecationWarning`.
+ Python 3.9 switched to a PEG parser (see :pep:`617`), and Python 3.10 may
+ include new language syntax that is not parsable by lib2to3's LL(1) parser.
+ The ``lib2to3`` module may be removed from the standard library in a future
+ Python version. Consider third-party alternatives such as `LibCST`_ or
+ `parso`_.
+ (Contributed by Carl Meyer in :issue:`40360`.)
+
+.. _LibCST: https://libcst.readthedocs.io/
+.. _parso: https://parso.readthedocs.io/
Removed
=======