analyzer plugins: Support reporting diagnostics on YAML files

[srawlins]

Currently analyzer plugins cannot only report diagnostics in Dart files (or... it's not explicitly supported that you can report on other types of files).

It should be a pretty easy effort for DAS to report changes to some prime YAML files like pubspec.yaml, analysis_options.yaml, or build.yaml. But there are less common ones like monorepo.yaml, so we could maybe support all YAML files. We can report changes and also accept diagnostics and quick fixes and assists for YAML files.

[FMorschel]

Quick-fixes are not yet done by DAS (#55985).

I was actually wondering if we could do some more base work to allow plugin authors to use plugins to analyse different files like .drift or something if they want to. Not sure if the team would be interested in allowing this, but I think if we do a solid foundation for both yaml and dart files, we could share that with plugin authors. It also obviously wouldn't be a priority for us to add soon, but if you are interested, should I open another issue, or could we track this as base work here?

[srawlins]

Yeah there's a mechanism for this here. But I think it's sort of limited to the files that DAS is already watching, and I don't believe DAS is watching, from your example, .drift files. Whether a plugin's response to a PluginVersionCheck could trigger DAS to watch .drift files... it seems like it might be a big effort; I have not investigated.

[bwilkerson]

... use plugins to analyse different files like .drift or something ...

As I understand it, and I might be wrong, the IDE plugins generally have to let the IDE know what kinds of files they are able to provide support for. I think they're currently registering interest in .dart and .yaml files, but I'm fairly sure that's all. If we want to extend that we'll need to update the IDE plugins as well as the analysis server.

Without a strong reason for doing so I don't think we're likely to start supporting other file types. The analysis server plugins are not a replacement for building an IDE plugin, they're a way to extend what the analysis server is already doing, and the analysis server doesn't need to analyze any other kinds of files.