Implement use strict linting (#7223)

* implement use strict linting

* commit changes

* add additional check for strict

build/lib/tslint/noUselessStrictRule.js

@@ -0,0 +1,28 @@
+"use strict";
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the Source EULA. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+Object.defineProperty(exports, "__esModule", { value: true });
+const Lint = require("tslint");
+class Rule extends Lint.Rules.TypedRule {
+    applyWithProgram(sourceFile, program) {
+        if (program.getCompilerOptions().alwaysStrict) {
+            return this.applyWithWalker(new NoUselessStrictRuleWalker(sourceFile, this.getOptions()));
+        }
+        return [];
+    }
+}
+exports.Rule = Rule;
+class NoUselessStrictRuleWalker extends Lint.RuleWalker {
+    visitStringLiteral(node) {
+        this.checkStringLiteral(node);
+        super.visitStringLiteral(node);
+    }
+    checkStringLiteral(node) {
+        const text = node.getText();
+        if (text === '\'use strict\'' || text === '"use strict"') {
+            this.addFailureAtNode(node, 'use strict directive is unnecessary');
+        }
+    }
+}

build/lib/tslint/noUselessStrictRule.ts

@@ -0,0 +1,30 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the Source EULA. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import * as Lint from 'tslint';
+import * as ts from 'typescript';
+
+export class Rule extends Lint.Rules.TypedRule {
+    public applyWithProgram(sourceFile: ts.SourceFile, program: ts.Program): Lint.RuleFailure[] {
+		if (program.getCompilerOptions().alwaysStrict) {
+			return this.applyWithWalker(new NoUselessStrictRuleWalker(sourceFile, this.getOptions()));
+		}
+		return [];
+	}
+}
+
+class NoUselessStrictRuleWalker extends Lint.RuleWalker {
+	protected visitStringLiteral(node: ts.StringLiteral): void {
+		this.checkStringLiteral(node);
+		super.visitStringLiteral(node);
+	}
+
+	private checkStringLiteral(node: ts.StringLiteral): void {
+		const text = node.getText();
+		if (text === '\'use strict\'' || text === '"use strict"') {
+			this.addFailureAtNode(node, 'use strict directive is unnecessary');
+		}
+	}
+}