Q:

Create diagnostics entries without language server in Visual Studio Code

I have a reasonably simple extension for Visual Studio Code where I want to apply some warning, if possible, without having to implement an entire language server for it. Is there a way to do this directly on the document or editor objects? I'm not finding anything when inspecting the objects. 

A:

So, I was able to do this after a bunch of digging. 
import { languages, Diagnostic, DiagnosticSeverity } from 'vscode';

... 

let diagnosticCollection = languages.createDiagnosticCollection("stuff");
let diagnostics : Diagnostic[] = [];

...

diagnostics.push(new Diagnostic(range, message, DiagnosticSeverity.Warning));

diagnosticCollection.set(document.uri, diagnostics);

