PEP 646 grammar changes are not documented

[JelleZijlstra]

PEP-646 made some changes to the grammar, but neither is reflected in the language reference:

• https://docs.python.org/3/reference/expressions.html#subscriptions should mention that the right-hand side of a subscript can be a starred expression
• https://docs.python.org/3/reference/compound_stmts.html#function-definitions should mention that the annotation of an *args parameter can be a starred expression

References: python/peps#3671 (making the PEP final); #31018 (implementation of the grammar changes)

Linked PRs

• gh-115528: Update language reference for PEP 646 #120294
• gh-115528: Update language reference for PEP 646 #121181
• [3.13] gh-115528: Update language reference for PEP 646 (GH-121181) #124632
• [3.12] gh-115528: Update language reference for PEP 646 (GH-121181) #124633

[hugovk]

@mrahtz Hello! Pinging as author of #31018 and co-author of PEP-646.

There's still a bit of work to be done for the PEP: document the changes, and mark the PEP as Final with a link to the docs.

Please could you co-ordinate with your co-authors to finish this off? Thank you!

[mrahtz]

Ooh thanks for the heads up! I'll try to get to this in the next week or so.