Add live error feedback as you type

README.md

@@ -24,6 +24,7 @@ This extension adds rich language support for the Go language to VS Code, includ
 - Generate unit tests skeleton (using `gotests`)
 - Add Imports (using `gopkgs`)
 - Add/Remove Tags on struct fields (using `gomodifytags`)
+- Semantic/Syntactic error reporting as you type (using `gotype-live`)
 - [_partially implemented_] Debugging (using `delve`)
 
 ### IDE Features

package.json

@@ -541,6 +541,26 @@
           },
           "description": "Tags and options configured here will be used by the Add Tags command to add tags to struct fields. If promptForTags is true, then user will be prompted for tags and options. By default, json tags are added."
         },
+        "go.liveErrors": {
+          "type": "object",
+          "properties": {
+            "enabled": {
+              "type": "boolean",
+              "default": false,
+              "description": "If true, runs gotype on the file currently being edited and reports any semantic or syntactic errors found."
+            },
+            "delay": {
+              "type": "number",
+              "default": 500,
+              "description": "The number of milliseconds to delay before execution. Resets with each keystroke."
+            }
+          },          
+          "default": {
+            "enabled": false,
+            "delay": 500
+          },
+          "description": "Use gotype on the file currently being edited and report any semantic or syntactic errors found after configured delay."
+        },
         "go.removeTags": {
           "type": "object",
           "properties": {

src/goInstallTools.ts

@@ -14,6 +14,7 @@ import { showGoStatus, hideGoStatus } from './goStatus';
 import { getGoRuntimePath, resolvePath } from './goPath';
 import { outputChannel } from './goStatus';
 import { getBinPath, getToolsGopath, getGoVersion, SemVersion, isVendorSupported } from './util';
+import { goLiveErrorsEnabled } from './goLiveErrors';
 
 let updatesDeclinedTools: string[] = [];
 
@@ -28,6 +29,9 @@ function getTools(goVersion: SemVersion): { [key: string]: string } {
 		'gorename': 'golang.org/x/tools/cmd/gorename',
 		'gomodifytags': 'github.com/fatih/gomodifytags'
 	};
+	if (goLiveErrorsEnabled()) {
+		tools['gotype-live'] = 'github.com/tylerb/gotype-live';
+	}
 
 	// Install the doc/def tool that was chosen by the user
 	if (goConfig['docsTool'] === 'godoc') {

src/goLiveErrors.ts

@@ -0,0 +1,88 @@
+'use strict';
+
+import vscode = require('vscode');
+import { byteOffsetAt, getBinPath } from './util';
+import cp = require('child_process');
+import path = require('path');
+import { promptForMissingTool } from './goInstallTools';
+import { errorDiagnosticCollection } from './goMain';
+
+// Interface for settings configuration for adding and removing tags
+interface GoLiveErrorsConfig {
+	delay: number;
+	enabled: boolean;
+}
+
+let runner;
+
+export function goLiveErrorsEnabled() {
+	let goConfig = <GoLiveErrorsConfig>vscode.workspace.getConfiguration('go')['liveErrors'];
+	if (goConfig === null || goConfig === undefined || !goConfig.enabled) {
+		return false;
+	}
+	let autoSave = vscode.workspace.getConfiguration('files')['autoSave'];
+	if (autoSave !== null && autoSave !== undefined && autoSave !== 'off') {
+		return false;
+	}
+	return goConfig.enabled;
+}
+
+// parseLiveFile runs the gotype command in live mode to check for any syntactic or
+// semantic errors and reports them immediately
+export function parseLiveFile(e: vscode.TextDocumentChangeEvent) {
+	if (e.document.isUntitled) {
+		return;
+	}
+	if (e.document.languageId !== 'go') {
+		return;
+	}
+	if (!goLiveErrorsEnabled()) {
+		return;
+	}
+
+	if (runner != null) {
+		clearTimeout(runner);
+	}
+	runner = setTimeout(function(){
+		processFile(e);
+		runner = null;
+	}, vscode.workspace.getConfiguration('go')['liveErrors']['delay']);
+}
+
+// processFile does the actual work once the timeout has fired
+function processFile(e: vscode.TextDocumentChangeEvent) {
+	let uri = e.document.uri;
+	let gotypeLive = getBinPath('gotype-live');
+	let fileContents = e.document.getText();
+	let fileName = e.document.fileName;
+	let args = ['-e', '-a', '-lf=' + fileName, path.dirname(fileName)];
+	let p = cp.execFile(gotypeLive, args, (err, stdout, stderr) => {
+		if (err && (<any>err).code === 'ENOENT') {
+			promptForMissingTool('gotype-live');
+			return;
+		}
+
+		errorDiagnosticCollection.delete(uri);
+
+		if (err) {
+			// we want to take the error path here because the command we are calling
+			// returns a non-zero exit status if the checks fail
+			let diagnostics = [];
+
+			stderr.split('\n').forEach(error => {
+				if (error === null || error.length === 0) {
+					return;
+				}
+				// extract the line, column and error message from the gotype output
+				let [_, line, column, message] = /^.+:(\d+):(\d+):\s+(.+)/.exec(error);
+
+				let range = new vscode.Range(+line - 1, +column, +line - 1, +column);
+				let diagnostic = new vscode.Diagnostic(range, message, vscode.DiagnosticSeverity.Error);
+				diagnostics.push(diagnostic);
+			});
+
+			errorDiagnosticCollection.set(uri, diagnostics);
+		}
+	});
+	p.stdin.end(fileContents);
+}

src/goMain.ts

@@ -32,8 +32,10 @@ import { isGoPathSet, getBinPath, sendTelemetryEvent } from './util';
 import { LanguageClient } from 'vscode-languageclient';
 import { clearCacheForTools } from './goPath';
 import { addTags, removeTags } from './goModifytags';
+import { parseLiveFile } from './goLiveErrors';
 
-let diagnosticCollection: vscode.DiagnosticCollection;
+export let errorDiagnosticCollection: vscode.DiagnosticCollection;
+let warningDiagnosticCollection: vscode.DiagnosticCollection;
 
 export function activate(ctx: vscode.ExtensionContext): void {
 	let useLangServer = vscode.workspace.getConfiguration('go')['useLanguageServer'];
@@ -81,12 +83,15 @@ export function activate(ctx: vscode.ExtensionContext): void {
 	ctx.subscriptions.push(vscode.languages.registerRenameProvider(GO_MODE, new GoRenameProvider()));
 	ctx.subscriptions.push(vscode.languages.registerCodeActionsProvider(GO_MODE, new GoCodeActionProvider()));
 
-	diagnosticCollection = vscode.languages.createDiagnosticCollection('go');
-	ctx.subscriptions.push(diagnosticCollection);
+	errorDiagnosticCollection = vscode.languages.createDiagnosticCollection('go-error');
+	ctx.subscriptions.push(errorDiagnosticCollection);
+	warningDiagnosticCollection = vscode.languages.createDiagnosticCollection('go-warning');
+	ctx.subscriptions.push(warningDiagnosticCollection);
 	vscode.workspace.onDidChangeTextDocument(removeCodeCoverage, null, ctx.subscriptions);
 	vscode.workspace.onDidChangeTextDocument(removeTestStatus, null, ctx.subscriptions);
 	vscode.window.onDidChangeActiveTextEditor(showHideStatus, null, ctx.subscriptions);
 	vscode.window.onDidChangeActiveTextEditor(getCodeCoverage, null, ctx.subscriptions);
+	vscode.workspace.onDidChangeTextDocument(parseLiveFile, null, ctx.subscriptions);
 
 	startBuildOnSaveWatcher(ctx.subscriptions);
 
@@ -231,9 +236,9 @@ function runBuilds(document: vscode.TextDocument, goConfig: vscode.WorkspaceConf
 
 	let uri = document.uri;
 	check(uri.fsPath, goConfig).then(errors => {
-		diagnosticCollection.clear();
+		errorDiagnosticCollection.clear();
 
-		let diagnosticMap: Map<string, vscode.Diagnostic[]> = new Map();
+		let diagnosticMap: Map<string, Map<vscode.DiagnosticSeverity, vscode.Diagnostic[]>> = new Map();
 
 		errors.forEach(error => {
 			let canonicalFile = vscode.Uri.file(error.file).toString();
@@ -247,16 +252,21 @@ function runBuilds(document: vscode.TextDocument, goConfig: vscode.WorkspaceConf
 				endColumn = text.length - trailing.length;
 			}
 			let range = new vscode.Range(error.line - 1, startColumn, error.line - 1, endColumn);
-			let diagnostic = new vscode.Diagnostic(range, error.msg, mapSeverityToVSCodeSeverity(error.severity));
+			let severity = mapSeverityToVSCodeSeverity(error.severity);
+			let diagnostic = new vscode.Diagnostic(range, error.msg, severity);
 			let diagnostics = diagnosticMap.get(canonicalFile);
 			if (!diagnostics) {
-				diagnostics = [];
+				diagnostics = new Map<vscode.DiagnosticSeverity, vscode.Diagnostic[]>();
 			}
-			diagnostics.push(diagnostic);
+			if (!diagnostics[severity]) {
+				diagnostics[severity] = [];
+			}
+			diagnostics[severity].push(diagnostic);
 			diagnosticMap.set(canonicalFile, diagnostics);
 		});
-		diagnosticMap.forEach((diags, file) => {
-			diagnosticCollection.set(vscode.Uri.parse(file), diags);
+		diagnosticMap.forEach((diagMap, file) => {
+			errorDiagnosticCollection.set(vscode.Uri.parse(file), diagMap[vscode.DiagnosticSeverity.Error]);
+			warningDiagnosticCollection.set(vscode.Uri.parse(file), diagMap[vscode.DiagnosticSeverity.Warning]);
 		});
 	}).catch(err => {
 		vscode.window.showInformationMessage('Error: ' + err);