SourceKit-LSP file status UX

[DavidGoldman]

@cukr

Rust language server does that and it's great. As far as I can tell it only tells you "RLS" or "RLS⚙️", but even just knowing that the language server is working is extremely calming and reassuring when you struggled a lot with installing other language servers.

Yeah, we could do something like that and then display the message on hover. This fits VSCode well because you don't want to take up too much status bar space. Do you know if the RLS uses the LSP's progress API for this?

@akyrtzi

I like the general direction and particularly like this:

that will allow us to do things like holding off diagnostics if we think we will emit false errors due to missing inputs e.g. Xcode prebuilding swiftmodules

On the specifics, for the "Build System" section, would it be better to have the build system communicate to the editor directly, instead of funneling all its status through LSP?
Presumably the build system should already be communicating with the editor for building status & output etc., it could also use the same mechanism to communicate its activity status for work requested by SKLSP.

For example, I think it's better if displaying a build activity/log for "prebuilding" is something that goes through the same mechanism as a normal build.

Yeah, that is definitely one option, although it would need some integration into SourceKit-LSP to note the prebuilding so diagnostics can be withheld.

I guess it depends how reusable we want it to be - if it lives in SourceKit-LSP itself it becomes more of a standard UI component to all build systems SourceKit-LSP supports (if they provide the updates), otherwise it'll be on a per-build system basis (through its backchannel to the editor).

The limitation of the generalization here is limited UI control, including no interaction (unless we can somehow register a command to the status bar item and send it over the build system).