Keep the literal type of the AdvertisingData legacy constants

[zyv]

Hi @zxzxwu,

I'm not sure how much you care about the legacy constants, but since they are still there, maybe the typing is still worth fixing. I didn't actually know about the new syntax, and that's why I ran into this issue when typechecking my project:

AdvertisingData forwards each AdvertisingData.Type member as a class-level constant for backward compatibility. Those constants are unannotated, so a type checker widens them to AdvertisingData.Type, no Literal[Type...] overload of get() or get_all() matches them, and the return type falls back to the AdvertisingDataObject union:

ad.get(AdvertisingData.COMPLETE_LOCAL_NAME)       ->  the whole union
ad.get(AdvertisingData.Type.COMPLETE_LOCAL_NAME)  ->  str | None

The overloads arrived with the constant block in f321143, so they have never been reachable through the forwarded names. Every in-tree call through a forwarded name passes raw=True, which selects on the other parameter, so the mypy run in CI never reached the broken path.

My patch declares the backward-compatibility block Final, which keeps the literal type of each assignment and restores overload selection. pyright treats an all-caps class variable as implicitly Final and already reports str | None for both spellings; mypy, ty and zuban widen.

invoke project.check-types runs mypy over tests/, so the assert_type calls in the new test fail that gate if an overload stops resolving. mypy skips the body of an unannotated function, hence the -> None.

[zxzxwu]

Interesting. My LSP (pyright, pyrefly) did consider them literals

But still this assertion doesn't pass without Final

[zyv]

Interesting. My LSP (pyright, pyrefly) did consider them literals...but still this assertion doesn't pass without Final.

Yep, I think that the reason, as I mentioned, is that ALL_CAPS are implicitly considered Final in the LSP context, but when assertions are evaluated, it behaves like all the other type checkers - nice footgun under the guise of “user-friendliness," I would say, but that's just me.