Pin mypy_extensions to <2

[cdce8p]

mypy_extensions.TypedDict and mypy_extensions.NoReturn were recently deprecated and will be removed eventually. Add an upper bound now so we don't break old code using these types in the future, after they are removed from mypy_extensions.

[hauntsaninja]

Hmm could you spell out the situation in which this bound is useful?

[github-actions]

According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅

[cdce8p]

Hmm could you spell out the situation in which this bound is useful?

Hmm, it depends. The user has to pin an old mypy version without pinning mypy_extensions while using the old mypy_extensions.TypedDict. If the environment is setup from scratch, version 2.0 would be installed causing a RuntimeError. Notably, mypy would still be fine, as we only use the stub for type checking which is shipped with mypy itself.

Tbh I'm not sure myself how common that is. For typing_extensions I've seen lots of pins, not so much for mypy_extensions. Then again the fix for the user would be trivial.

Ideally everybody has stopped the old TypedDict / NoReturn by then anyway.

What do you think? In the end it's just an edge case anyway, so I'd be also be fine if we don't do it.

[hauntsaninja]

Hm, that sounds niche, and I'm not even sure the mypy version even matters here (if the user is pinning the mypy version, they're not going to pick up this PR). I think we should just roll forward, if we want to avoid breaking things here then we should just not make the breaking change in mypy_extensions in the first place.

Going to close, but lmk if I got it wrong!

[cdce8p]

Hm, that sounds niche

Yeah, it is. I debated it myself if I should even open it. Was slightly in favor, so I did.

I'm not even sure the mypy version even matters here (if the user is pinning the mypy version, they're not going to pick up this PR).

Yes, this would have only applied to mypy versions released between now and 2.0 making it even more niche.

I think we should just roll forward, if we want to avoid breaking things here then we should just not make the breaking change in mypy_extensions in the first place.

I'd personally be completely fine with removing it after a deprecation period. The sense I've got so far though is that breaking changes in mypy are heavily discouraged. It would just be awesome if we could get rid of mypy_extensions.TypedDict at some point.

Going to close, but lmk if I got it wrong!

👍🏻 Works for me.