Analyzer needs to handle @optionalTypeArgs w/ static extensions

[srawlins]

Take this example from the static extension spec:

import "all.dart";  // exposes extensions `Foo`, `Bar` and `Baz`.
// ...
main() {
  // ...
  Baz("ok").baz();  // Explicit reference to `Baz` extension.
  // ...
}

1. Can the extension, Baz, be marked @optionalTypeArgs? (I think so)

In the context of linter rules which take @optionalTypeArgs under consideration, and the strict-raw-types static analysis mode:

2. If Baz<T> is an extension on a class, C<T>, then I think Baz("ok") is not ok; analyzer/linter should hint/lint where appropriate then Baz("ok") is fine; inference takes place here, similar to how it does on constructors.
3. The extension, extension Baz on C, where C is generic (e.g. C<T>), should be considered a raw type; analyzer/linter should hint/lint where appropriate.
4. The extension, extension on C, where C is generic (e.g. C<T>), should be considered a raw type; analyzer/linter should hint/lint where appropriate.

Any of the above can be suppressed with @optionalTypeArgs.

CC @pq

[bwilkerson]

I think it makes sense to allow @optionalTypeArgs on extensions. We should also allow it on mixins, and update the comment to reflect all of these options.

Should we also allow the annotation on generic methods?

[pq]

I think it makes sense to allow @optionalTypeArgs on extensions.

👍

@srawlins: have you done a survey of what lints will be affected here? Happy to help fix up (but . haven't taken a look yet...)

[srawlins]

We should also allow it on mixins, and update the comment to reflect all of these options.

Should we also allow the annotation on generic methods?

Ah, yes, and yes. We might already have the mixin support, but we'd still need to update the comment.

have you done a survey of what lints will be affected here?

Ah, I thought it was several lint rules; it appears to be just always_specify_types. 🎉

[pq]

Ah, I thought it was several lint rules; it appears to be just always_specify_types

Great! Do you want to open a tracking issue on the linter? Feel free to assign to me if you're not already planning to tackle it.

Thanks!

[srawlins]

@pq Done: #58007

[pq]

Thanks @srawlins!

[srawlins]

Implemented.