Separate "static" private and public fields into a different flag

[littledan]

TC39 demoted static private and public field declarations to Stage 2 (PR). They are being pursued in a separate proposal instead. Static fields should be moved to a separate flag which is included in the Stage 2 preset.

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[Jessidhia]

I'm not sure this is possible at all without splitting it into two separate transforms 🤔

[littledan]

I implemented the split in V8 by throwing a syntax error when seeing static fields in the syntax. The actual implementation under that stayed untouched, so most of the work was getting the tests split up properly.

[littledan]

By the way, about compatibility with existing users of the transform: What if we made two smaller transforms, public-instance-fields and public-static-fields, and made the existing transform alias the combination?

[nicolo-ribaudo]

That shouldn't be a problem, since we already removed the old export-extensions plugin when we split it.

[xtuc]

@nicolo-ribaudo what should we do here? could we close this issue now?

[nicolo-ribaudo]

We can do this, it should be straightforward and non-breaking with the new class-features plugin.

@littledan We were planning to have only three flags: "class fields", "private methods" and "decorators". What would you prefer?

[xtuc]

Ok, should we change this issue to a beginner-friendly one?

[nicolo-ribaudo]

Yes 👍
I'll write a good description on how to separate them later.

[littledan]

At this point, I am not sure if there is much demand for separating out static and instance features. The current split seems fine to me.

[nicolo-ribaudo]

Ok 👍