Provide some sort of diagnostics command in TSServer

[DanielRosenwasser]

We often get feedback from VS/VS Code users that TSServer is slow, but the amount of time it takes to diagnose the issue is a bit much for them (e.g. enabling logging etc.)

The proposal here is for TSServer to provide some of the same information as --listFiles and --extendedDiagnostics which you can get from the command line. Editors could then open a buffer that could let them and our teams diagnose issues.

Here's an example of what we could return to the editor:

{
    diagnostics: {
        // ...
    },
    compilerOptions: {
        // ...
    },
    files: [
        { filePath: "...", size: 1234 }
    ]
}

The editor could choose to display this however it wants.

[DanielRosenwasser]

@mjbvz @amcasey

[DanielRosenwasser]

Things that might be useful

• Version
• Options (e.g. quote style)
• Projects and what they contain
  • Project kinds (inferred, configured, etc.)
  • include/exclude?
  • file list
  • largest file and its size (maybe just sort files by size)
  • number of files
• number of errors reported
• open file list
  • size, longest line length
• GUIDs of project kinds?

[DanielRosenwasser]

It sounds like editors can just maintain this information as well. Maybe we don't need to do anything in tsserver.

[sheetalkamat]

Since there was no work needed here, is it safe to close this?

[amcasey]

Fine by me. We're tracking the VS work internally.