src/goMain.ts: show notification about go.useLanguageServer

The notification provides options to open the settings
and suppress the notification forever.

Also update package.json to change the description of
the go.useLanguageServer setting.

Updates #2799

Change-Id: Ib0e4e4414942ab083d1932abcb34f5871911d3da
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/501198
Run-TryBot: Hyang-Ah Hana Kim <hyangah@gmail.com>
Reviewed-by: Jamal Carvalho <jamal@golang.org>
Reviewed-by: Suzy Mueller <suzmue@golang.org>
TryBot-Result: kokoro <noreply+kokoro@google.com>

Author: hyangah

docs/settings.md

@@ -583,7 +583,7 @@ When enabled, the extension automatically checks the Go proxy if there are updat
 Default: `true`
 ### `go.useLanguageServer`
 
-Use the Go language server "gopls" from Google for powering language features like code navigation, completion, refactoring, formatting & diagnostics.
+Enable intellisense, code navigation, refactoring, formatting & diagnostics for Go. The features are powered by the Go language server "gopls".
 
 Default: `true`
 ### `go.vetFlags`

package.json

@@ -1575,7 +1575,7 @@
         "go.useLanguageServer": {
           "type": "boolean",
           "default": true,
-          "description": "Use the Go language server \"gopls\" from Google for powering language features like code navigation, completion, refactoring, formatting & diagnostics."
+          "description": "Enable intellisense, code navigation, refactoring, formatting & diagnostics for Go. The features are powered by the Go language server \"gopls\"."
         },
         "go.languageServerFlags": {
           "type": "array",

src/goMain.ts

@@ -40,7 +40,7 @@ import { GO_MODE } from './goMode';
 import { GO111MODULE, goModInit, isModSupported } from './goModules';
 import { playgroundCommand } from './goPlayground';
 import { GoRunTestCodeLensProvider } from './goRunTestCodelens';
-import { disposeGoStatusBar, expandGoStatusBar, updateGoStatusBar } from './goStatus';
+import { disposeGoStatusBar, expandGoStatusBar, outputChannel, updateGoStatusBar } from './goStatus';
 
 import { vetCode } from './goVet';
 import {
@@ -375,6 +375,23 @@ function lintDiagnosticCollectionName(lintToolName: string) {
 
 async function showDeprecationWarning() {
 	const cfg = getGoConfig();
+	const disableLanguageServer = cfg['useLanguageServer'];
+	if (disableLanguageServer === false) {
+		const promptKey = 'promptedLegacyLanguageServerDeprecation';
+		const prompted = getFromGlobalState(promptKey, false);
+		if (!prompted) {
+			const msg =
+				'When [go.useLanguageServer](command:workbench.action.openSettings?%5B%22go.useLanguageServer%22%5D) is false, IntelliSense, code navigation, and refactoring features for Go will stop working. Linting, debugging and testing other than debug/test code lenses will continue to work. Please see [Issue 2799](https://go.dev/s/vscode-issue/2799).';
+			const selected = await vscode.window.showInformationMessage(msg, 'Open settings', "Don't show again");
+			switch (selected) {
+				case 'Open settings':
+					vscode.commands.executeCommand('workbench.action.openSettings', 'go.useLanguageServer');
+					break;
+				case "Don't show again":
+					updateGlobalState(promptKey, true);
+			}
+		}
+	}
 	const experimentalFeatures = cfg['languageServerExperimentalFeatures'];
 	if (experimentalFeatures) {
 		// TODO(golang/vscode-go#50): Eventually notify about deprecation of