Don't suppress typeshed warnings when using --custom-typeshed-dir

[nipunn1313]

When using --custom-typeshed-dir, I'm intentionally indicating that I'm using my own edited version of typeshed. It would be nice for typeshed warnings to be surfaced under these conditions.

[nipunn1313]

@ddfisher helped me debug something and recommended this.

[msullivan]

Which typeshed warnings do you mean?

[nipunn1313]

er I mean mypy typeshed errors.

In my case, I was co-developing my own project (mypy-protobuf) and typeshed using --custom-typeshed-dir

In typeshed, I used a type (Generic specifically) and forgot to import it from typing import Generic.

When type-checking my own code, it silently switched Generic to Any. My understanding is that this was an intentional decision to hide errors within typeshed.

I was able to catch the issue by running the typeshed tests, but for convenience when doing this co-developing, it would be nice to see those errors when mypy-ing my own project with this custom-typeshed-dir flag.

[JukkaL]

I like this idea. It's also possible that we'll start reporting errors in typeshed always, after we've switched to modular typeshed. (We may also have to rename --custom-typeshed-dir.)

[srittau]

Please note that typeshed might use less strict options than other projects. For example, --warn-return-any would raise lots of warnings in typeshed. Bad example, but the point stands.

[srittau]

One possible solution are per-directory mypy config files that override other configuration options.

[JukkaL]

Ah a good point. A potentially simpler option would be to use a fixed set of strictness options for typeshed. Anyway, this sounds a bit complicated, so I'm removing the good-first-issue label.

[emmatyping]

Now that we have modular typeshed (yay!!), I think it would be good to revisit this. Setting fixed options for typeshed seems like a very good option.

I'm not sure if that would be easy though, we'd have to fake per-module flags or something similar.