[clangd] Clean the cache of file statuses on vscode-clangd when clangd crashes.

[hokein]

Summary

Clear the cached file statuses, otherwise We will leave some garbage texts on
the status bar when clangd crashes.

[ilya-biryukov]

LGTM

clangd/clients/clangd-vscode/src/extension.ts

127

This looks scary, if we end up doing that in too many places, the code would become completely unreadable.

Have no idea how to make it better, but a very general observation is that we'd be better off with dropping all the state we have when clangd crashes and starting from scratch, rather than trying to keep old components and bring them into a sensible state when crashes happen.

No need to do anything right now, just something to keep in mind for the future.

[hokein]

clangd/clients/clangd-vscode/src/extension.ts

127

Acked.

clangd/clients/clangd-vscode/src/extension.ts

updateStatus() {
         if (!status) {
           this.statusBarItem.hide();
           return;
         }
         this.statusBarItem.text = `clangd: ` + status.state;
         this.statusBarItem.show();
     }
 
+    clear() {
+        this.statuses.clear();
+        this.statusBarItem.hide();
+    }
+
     dispose() {
         this.statusBarItem.dispose();
     }
 }
 
 /**
  *  this method is called when your extension is activate
  *  your extension is activated the very first time the command is executed
context.subscriptions.push(vscode.commands.registerCommand(
         const doc = await vscode.workspace.openTextDocument(
             vscode.Uri.parse(sourceUri));
         vscode.window.showTextDocument(doc);
       }));
     const status = new FileStatus();
     context.subscriptions.push(vscode.window.onDidChangeActiveTextEditor(() => {
         status.updateStatus();
     }));
-    clangdClient.onReady().then(() => {
+    clangdClient.onDidChangeState(
+        ({ newState }) => {
+            if (newState == vscodelc.State.Running) {
+                // clangd starts or restarts after crash.
                 clangdClient.onNotification(
                     'textDocument/clangd.fileStatus',
                     (fileStatus) => { status.onFileUpdated(fileStatus); });
+            } else if (newState == vscodelc.State.Stopped) {
+                // Clear all cached statuses when clangd crashes.
+                status.clear();
+            }
         })
 }