bpo-35975: Support parsing earlier minor versions of Python 3 (GH-12086)
This adds a `feature_version` flag to `ast.parse()` (documented) and `compile()` (hidden) that allow tweaking the parser to support older versions of the grammar. In particular if `feature_version` is 5 or 6, the hacks for the `async` and `await` keyword from PEP 492 are reinstated. (For 7 or higher, these are unconditionally treated as keywords, but they are still special tokens rather than `NAME` tokens that the parser driver recognizes.)
https://bugs.python.org/issue35975
diff --git a/Doc/library/token.rst b/Doc/library/token.rst
index 4936e9a..5c641ef 100644
--- a/Doc/library/token.rst
+++ b/Doc/library/token.rst
@@ -88,3 +88,6 @@
.. versionchanged:: 3.8
Added :data:`TYPE_COMMENT`.
+ Added :data:`AWAIT` and :data:`ASYNC` tokens back (they're needed
+ to support parsing older Python versions for :func:`ast.parse` with
+ ``feature_version`` set to 6 or lower).