Validate that editor plugin classes require #[class(tool)]

[TitanNano]

Editor plugin classes are editor only and thus require #[class(tool)] as they are not used in game

Details on how a class might be used is available in extension_api.json under classes.*.api_type (e.g. core or editor) and should be taken from there at some point. Matching the Editor prefix seems good enough for now, as it covers all the plugin classes. There is most likely no point extending the remaining editor only classes, but I haven't looked into it further.

[GodotRust]

API docs are being generated and will be shortly available at: https://godot-rust.github.io/docs/gdext/pr-852

[Bromeon]

Related: #850

There is also the attribute key #[class(editor_plugin)] -- should we check against that, rather than tool?

[TitanNano]

There is also the attribute key #[class(editor_plugin)] -- should we check against that, rather than tool?

But that is specifically for registering the EditorPlugin class, right? I guess we should additionally check that it is also present when the base is equal EditorPlugin...

[Bromeon]

Good point. I checked the original PR #393 and there's an interesting note:

The project will fail to compile if you try to make something an editor plugin that doesn't inherit from EditorPlugin. This is done by adding a doc-hidden constant to Inherits and trying to access it.

So there's already a validation that prevents #[class(editor_plugin)] from being used on other classes, and what you suggested is the inverse (having base=EditorPlugin but not editor_plugin).

I think later I'll entirely remove editor_plugin, since it's extra chore but logically equivalent to base=EditorPlugin. For now, you can thus ignore validations related to this key.

[Bromeon]

Maybe one point where #[class(editor_plugin)] could still be relevant is if we add intermediate classes between the most-derived Rust one and EditorPlugin, so the direct base class wouldn't be EditorPlugin anymore.

But even that could be somehow encoded into the type system. And currently such intermediate classes are not supported.

[Bromeon]

Thanks a lot!