Add support for PEP 646

[mrahtz]

BPO	43224
Nosy	@gvanrossum, @serhiy-storchaka, @JelleZijlstra, @lysnikolaou, @pablogsal, @Fidget-Spinner, @mrahtz, @mrahtz, @AlexWaygood, @cdce8p
PRs	bpo-43224: Initial implementation of PEP 646 in typing.py #24527 bpo-43224: Draft implementation of PEP 646 #30398 bpo-43224: Implement PEP 646 grammar changes #31018 bpo-43224: Implement PEP 646 changes to genericaliasobject.c #31019 bpo-43224: Implement PEP 646 changes to typing.py #31021 bpo-43224: Implement substitution of unpacked TypeVarTuple #31800 bpo-43224: Work around substitution of unpacked TypeVarTuple #31804 bpo-43224: Implement substitution of unpacked TypeVarTuple in C #31828 bpo-43224: Add more tests for typevar substitution #31844 bpo-43224: Fix Tuple[()].__args__ #31845 bpo-43224: Add tests for TypeVarTuple substitution in Annotated #31846 bpo-43224: Add TypeVarTuple.__name__ #31954 bpo-43224: Unpack concrete tuple types into a sequence of types #32030 bpo-43224: Forbid TypeVar substitution with Unpack #32031 bpo-43224: Implement pickling of TypeVarTuples #32119 bpo-43224: Add tests for pickling and copying of unpacked native tuple #32159

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2021-02-14.17:21:47.204>
labels = ['interpreter-core', 'tests', 'library', '3.11']
title = 'Add support for PEP 646'
updated_at = <Date 2022-04-05.02:52:50.682>
user = 'https://github.com/mrahtz'

bugs.python.org fields:

activity = <Date 2022-04-05.02:52:50.682>
actor = 'JelleZijlstra'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)', 'Tests', 'Parser']
creation = <Date 2021-02-14.17:21:47.204>
creator = 'mrahtz'
dependencies = []
files = []
hgrepos = []
issue_num = 43224
keywords = ['patch']
message_count = 9.0
messages = ['414715', '414935', '414991', '415514', '416020', '416022', '416074', '416689', '416727']
nosy_count = 10.0
nosy_names = ['gvanrossum', 'serhiy.storchaka', 'JelleZijlstra', 'lys.nikolaou', 'pablogsal', 'kj', 'matthew.rahtz', 'mrahtz', 'AlexWaygood', 'cdce8p']
pr_nums = ['24527', '30398', '31018', '31019', '31021', '31800', '31804', '31828', '31844', '31845', '31846', '31954', '32030', '32031', '32119', '32159']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = None
url = 'https://bugs.python.org/issue43224'
versions = ['Python 3.11']

[JelleZijlstra]

New changeset 7a793a3 by Matthew Rahtz in branch 'main':
bpo-43224: Implement PEP-646 changes to typing.py (GH-31021)
7a793a3

[serhiy-storchaka]

New changeset 5b1b9ea by Serhiy Storchaka in branch 'main':
bpo-43224: Implement substitution of unpacked TypeVarTuple (GH-31800)
5b1b9ea

[Fidget-Spinner]

New changeset af2277e by Matthew Rahtz in branch 'main':
bpo-43224: Implement PEP-646 changes to genericaliasobject.c (GH-31019)
af2277e

[JelleZijlstra]

New changeset 3a2b895 by Jelle Zijlstra in branch 'main':
bpo-43224: Add TypeVarTuple.__name__ (GH-31954)
3a2b895

[mrahtz]

Since things are piling up, here's a quick record of what I think the remaining tasks are: (in approximate order of priority)

1. Finish writing docs (is updating library/typing.html sufficient? bpo-47097: Add documentation for TypeVarTuple #32103)
2. Implement support for pickling of unpacked native tuples
3. Implement support and add tests for copy() of TypeVarTuple and unpacked tuple
4. Resolve the issue of how we implement type substitution (https://bugs.python.org/issue47006)

[JelleZijlstra]

1. Finish writing docs (is updating library/typing.html sufficient? bpo-47097: Add documentation for TypeVarTuple #32103)

We also need to add to the What's New for 3.11. I volunteered to do that for all the typing PEPs.

2. Implement support for pickling of unpacked native tuples

Linking your #76300

3. Implement support and add tests for copy() of TypeVarTuple and unpacked tuple

I believe this uses the same mechanism as pickling, so shouldn't need more work.

[JelleZijlstra]

New changeset e8e737b by Matthew Rahtz in branch 'main':
bpo-43224: Implement PEP-646 grammar changes (GH-31018)
e8e737b

[mrahtz]

1. Finish writing docs

Done once #32103 is merged.

2. Implement support for pickling of unpacked native tuples

Done once #32159 is merged.

4. Resolve the issue of how we implement type substitution (https://bugs.python.org/issue47006)

Will re-visit this now.

[JelleZijlstra]

New changeset 772d808 by Matthew Rahtz in branch 'main':
bpo-43224: typing: Add tests for pickling and copying of unpacked native tuple (GH-32159)
772d808

[gvanrossum]

@mrahtz @JelleZijlstra @serhiy-storchaka Is it okay if I unsubscribe from these conversations and let you all come up with a compromise? I feel that while we ought to have a policy formulated and mostly implemented by beta 1 (May 6), tweaks of both the policy and the implementation during the beta period until RC 1 (Aug/Sept?) should be allowable.

[mrahtz]

@gvanrossum Fine with me. Godspeed with the rest of your work for this release :)

[mrahtz]

Keeping track of things yet to do:

• Decide on/implement type substitution behaviour (PEP 646: Decide on substitution behavior #91162)
• Add tests for using * with things in typing.py (e.g. *Tuple[int]) now that the grammar PR has been merged (GH-87390: Add remaining tests for PEP 646 #98267)
• Implement support for/add tests for typing.get_args and typing.get_origin on unpacked types (GH-87390: Add remaining tests for PEP 646 #98267)
• Add some way of figure out whether a native tuple has been starred (gh-87390: Add __unpacked__ attribute to types.GenericAlias #92059)
• Finish making the runtime produce the results that the substitution tests https://github.com/python/cpython/blob/main/Lib/test/test_typing.py#L581 say it should
• Add substitution test for tuple[*Ts, T][str, *tuple[int, ...]] (GH-87390: Add remaining tests for PEP 646 #98267)
• Fix TODOs in test_genericalias.py (GH-87390: Add remaining tests for PEP 646 #98267)

Decided against doing:

• Disallow Unpack[Tuple] - I think it's simpler if we keep this valid, in accordance with the the general philosophy of "Keep the runtime lenient when it comes to typing"

[hauntsaninja]

How much of the checklist above is still relevant?

[mrahtz]

Thanks for the reminder! From a quick look, some of the items in the checklist are definitely still relevant. I'll try and find some time for this soon.

[AlexWaygood]

Thanks for the reminder! From a quick look, some of the items in the checklist are definitely still relevant. I'll try and find some time for this soon.

Friendly ping on this -- are the unchecked items on the checklist still to do, or is this issue ~complete now? :)

[mrahtz]

Whoops, sorry - we finished #98267 last year but I completely forgot to update the checklist. I believe we can go ahead and close this now :) (though I can't seem to do this myself because the issue was created before the move to GitHub or something? Can you do it on your end?)

[AlexWaygood]

Whoops, sorry - we finished #98267 last year but I completely forgot to update the checklist. I believe we can go ahead and close this now :)

No worries -- great to hear!

Can you do it on your end?)

I sure can. Thanks for all the work you put into this, it was a marathon!