bpo-34822: Simplify AST for subscription. (GH-9605)

* Remove the slice type.
* Make Slice a kind of the expr type instead of the slice type.
* Replace ExtSlice(slices) with Tuple(slices, Load()).
* Replace Index(value) with a value itself.

All non-terminal nodes in AST for expressions are now of the expr type.

1 files changed, 13 insertions, 0 deletions

diff --git a/Doc/whatsnew/3.9.rst b/Doc/whatsnew/3.9.rst
index 9056289..690dbba 100644
--- a/Doc/whatsnew/3.9.rst
+++ b/Doc/whatsnew/3.9.rst
@@ -535,6 +535,12 @@ Deprecated
 
   (Contributed by Victor Stinner in :issue:`39353`.)
 
+* :mod:`ast` classes ``Index`` and ``ExtSlice`` are considered deprecated
+  and will be removed in future Python versions.  ``value`` itself should be
+  used instead of ``Index(value)``.  ``Tuple(slices, Load())`` should be
+  used instead of ``ExtSlice(slices)``.
+  (Contributed by Serhiy Storchaka in :issue:`32892`.)
+
 * The :c:func:`PyEval_InitThreads` and :c:func:`PyEval_ThreadsInitialized`
   functions are now deprecated and will be removed in Python 3.11. Calling
   :c:func:`PyEval_InitThreads` now does nothing. The :term:`GIL` is initialized
@@ -667,10 +673,17 @@ Changes in the Python API
   since the *buffering* parameter has been removed.
   (Contributed by Victor Stinner in :issue:`39357`.)
 
+* Simplified AST for subscription. Simple indices will be represented by
+  their value, extended slices will be represented as tuples.
+  ``Index(value)`` will return a ``value`` itself, ``ExtSlice(slices)``
+  will return ``Tuple(slices, Load())``.
+  (Contributed by Serhiy Storchaka in :issue:`34822`.)
+
 * The :mod:`importlib` module now ignores the :envvar:`PYTHONCASEOK`
   environment variable when the :option:`-E` or :option:`-I` command line
   options are being used.
 
+
 CPython bytecode changes
 ------------------------