Make RoslynLanguageServer.start() no longer async

This method was accidentally doing a fire-and-forget since it didn't
await the underlying launch of the client process. We believe that's
what we want to continue to do, since awaiting the process launch
is dangerous since that can potentially deadlock when you have our
extension calling into Dev Kit or vice versa.

Author: jasonmalinowski

src/lsptoolshost/roslynLanguageServer.ts

@@ -150,9 +150,10 @@ export class RoslynLanguageServer {
     }
 
     /**
-     * Resolves server options and starts the dotnet language server process.
+     * Resolves server options and starts the dotnet language server process. The process is started asynchronously and this method will not wait until
+     * the process is launched.
      */
-    public async start(): Promise<void> {
+    public start(): void {
         let options = this.optionProvider.GetLatestOptions();
         let logLevel = options.languageServerOptions.logLevel;
         const languageClientTraceLevel = this.GetTraceLevel(logLevel);
@@ -235,13 +236,13 @@ export class RoslynLanguageServer {
     }
 
     /**
-     * Restarts the language server.
+     * Restarts the language server. This does not wait until the server has been restarted.
      * Note that since some options affect how the language server is initialized, we must
-     * re-create the LanguageClient instance instead of just stopping/starting it.
+     * re-create the LanguageClient instance instead of just stopping/starting it. 
      */
     public async restart(): Promise<void> {
         await this.stop();
-        await this.start();
+        this.start();
     }
 
     /**
@@ -635,7 +636,7 @@ export async function activateRoslynLanguageServer(context: vscode.ExtensionCont
     });
 
     // Start the language server.
-    await _languageServer.start();
+    _languageServer.start();
 }
 
 async function applyAutoInsertEdit(e: vscode.TextDocumentChangeEvent, token: vscode.CancellationToken) {