dataclasses: remove HasDataclassFields type parameter, use ClassVar

[nstarman]

Motivated by GalacticDynamics/dataclassish#78

[Copilot]

Pull request overview

Updates the optype.dataclasses.HasDataclassFields runtime protocol to remove its generic type parameter and to model __dataclass_fields__ as a class attribute, aligning the protocol more closely with how dataclasses expose metadata.

Changes:

• Deparametrized HasDataclassFields (removed TypeVar/Mapping-based generic parameter).
• Marked HasDataclassFields.__dataclass_fields__ (and the test fake) as ClassVar[...].
• Adjusted tests around isinstance/issubclass checks and added/updated type-checker ignores.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
optype/dataclasses.py	Removes generic parameterization and makes __dataclass_fields__ a ClassVar on the protocol.
tests/test_dataclasses.py	Updates test fixtures and assertions to match the new non-generic protocol shape.

[jorenham]

Looks like we've run into a pyrefly bug here. Do you want to report it or should I?

[nstarman]

Go for it! I'm sure you've interacted with them more.

[jorenham]

It looks like it has already been raised: facebook/pyrefly#2477

[jorenham]

What's up with the unverified commits?

[nstarman]

What's up with the unverified commits?

GitHub Codespaces. Something isn't signed in correctly. Or something.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.

[jorenham]

What's up with the unverified commits?

GitHub Codespaces. Something isn't signed in correctly. Or something.

Hmm, should be possible https://docs.github.com/en/codespaces/managing-your-codespaces/managing-gpg-verification-for-github-codespaces (but you probably already know that)

[nstarman]

Yeah, it's on my trusted repositories list for GPG signing.

[jorenham]

Thanks!