Emit modules in strict mode

src/compiler/emitter.ts

@@ -7383,7 +7383,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                 write(`], function(${exportFunctionForFile}) {`);
                 writeLine();
                 increaseIndent();
-                const startIndex = emitDirectivePrologues(node.statements, /*startWithNewLine*/ true);
+                const startIndex = emitDirectivePrologues(node.statements, /*startWithNewLine*/ true, /*ensureUseStrict*/ true);
                 emitEmitHelpers(node);
                 emitCaptureThisForNodeIfNecessary(node);
                 emitSystemModuleBody(node, dependencyGroups, startIndex);
@@ -7493,7 +7493,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                 writeModuleName(node, emitRelativePathAsModuleName);
                 emitAMDDependencies(node, /*includeNonAmdDependencies*/ true, emitRelativePathAsModuleName);
                 increaseIndent();
-                const startIndex = emitDirectivePrologues(node.statements, /*startWithNewLine*/ true);
+                const startIndex = emitDirectivePrologues(node.statements, /*startWithNewLine*/ true, /*ensureUseStrict*/ true);
                 emitExportStarHelper();
                 emitCaptureThisForNodeIfNecessary(node);
                 emitLinesStartingAt(node.statements, startIndex);
@@ -7505,7 +7505,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
             }
 
             function emitCommonJSModule(node: SourceFile) {
-                const startIndex = emitDirectivePrologues(node.statements, /*startWithNewLine*/ false);
+                const startIndex = emitDirectivePrologues(node.statements, /*startWithNewLine*/ false, /*ensureUseStrict*/ true);
                 emitEmitHelpers(node);
                 collectExternalModuleInfo(node);
                 emitExportStarHelper();
@@ -7534,7 +7534,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
 })(`);
                 emitAMDFactoryHeader(dependencyNames);
                 increaseIndent();
-                const startIndex = emitDirectivePrologues(node.statements, /*startWithNewLine*/ true);
+                const startIndex = emitDirectivePrologues(node.statements, /*startWithNewLine*/ true, /*ensureUseStrict*/ true);
                 emitExportStarHelper();
                 emitCaptureThisForNodeIfNecessary(node);
                 emitLinesStartingAt(node.statements, startIndex);
@@ -7676,19 +7676,38 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                 }
             }
 
-            function emitDirectivePrologues(statements: Node[], startWithNewLine: boolean): number {
+            function isUseStrictPrologue(node: ExpressionStatement): boolean {
+                return !!(node.expression as StringLiteral).text.match(/use strict/);
+            }
+
+            function ensureUseStrictPrologue(startWithNewLine: boolean, writeUseStrict: boolean) {
+                if (writeUseStrict) {
+                    if (startWithNewLine) {
+                        writeLine();
+                    }
+                    write("\"use strict\";");
+                }
+            }
+
+            function emitDirectivePrologues(statements: Node[], startWithNewLine: boolean, ensureUseStrict?: boolean): number {
+                let foundUseStrict = false;
                 for (let i = 0; i < statements.length; ++i) {
                     if (isPrologueDirective(statements[i])) {
+                        if (isUseStrictPrologue(statements[i] as ExpressionStatement)) {
+                            foundUseStrict = true;
+                        }
                         if (startWithNewLine || i > 0) {
                             writeLine();
                         }
                         emit(statements[i]);
                     }
                     else {
+                        ensureUseStrictPrologue(startWithNewLine || i > 0, !foundUseStrict && ensureUseStrict);
                         // return index of the first non prologue directive
                         return i;
                     }
                 }
+                ensureUseStrictPrologue(startWithNewLine, !foundUseStrict && ensureUseStrict);
                 return statements.length;
             }
 

tests/baselines/reference/APISample_compile.js

@@ -40,6 +40,7 @@ compile(process.argv.slice(2), {
          at: https://github.com/Microsoft/TypeScript/wiki/Using-the-Compiler-API#a-minimal-compiler
  *       Please log a "breaking change" issue for any API breaking change affecting this issue
  */
+"use strict";
 var ts = require("typescript");
 function compile(fileNames, options) {
     var program = ts.createProgram(fileNames, options);

tests/baselines/reference/APISample_linter.js

@@ -70,6 +70,7 @@ fileNames.forEach(fileName => {
          at: https://github.com/Microsoft/TypeScript/wiki/Using-the-Compiler-API#traversing-the-ast-with-a-little-linter
  *       Please log a "breaking change" issue for any API breaking change affecting this issue
  */
+"use strict";
 var ts = require("typescript");
 function delint(sourceFile) {
     delintNode(sourceFile);

tests/baselines/reference/APISample_transform.js

@@ -22,6 +22,7 @@ console.log(JSON.stringify(result));
          at: https://github.com/Microsoft/TypeScript/wiki/Using-the-Compiler-API#a-simple-transform-function
  *       Please log a "breaking change" issue for any API breaking change affecting this issue
  */
+"use strict";
 var ts = require("typescript");
 var source = "let x: string  = 'string'";
 var result = ts.transpile(source, { module: ts.ModuleKind.CommonJS });

tests/baselines/reference/APISample_watcher.js

@@ -109,6 +109,7 @@ watch(currentDirectoryFiles, { module: ts.ModuleKind.CommonJS });
          at: https://github.com/Microsoft/TypeScript/wiki/Using-the-Compiler-API#incremental-build-support-using-the-language-services
  *       Please log a "breaking change" issue for any API breaking change affecting this issue
  */
+"use strict";
 var ts = require("typescript");
 function watch(rootFileNames, options) {
     var files = {};

tests/baselines/reference/ExportAssignment7.js

@@ -5,6 +5,7 @@ export class C {
 export = B;
 
 //// [ExportAssignment7.js]
+"use strict";
 var C = (function () {
     function C() {
     }

tests/baselines/reference/ExportAssignment8.js

@@ -5,6 +5,7 @@ export class C {
 }
 
 //// [ExportAssignment8.js]
+"use strict";
 var C = (function () {
     function C() {
     }

tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedLocalVarsOfTheSameName.js

@@ -30,6 +30,7 @@ export module A {
 
 
 //// [part1.js]
+"use strict";
 var A;
 (function (A) {
     var Utils;
@@ -42,6 +43,7 @@ var A;
     A.Origin = { x: 0, y: 0 };
 })(A = exports.A || (exports.A = {}));
 //// [part2.js]
+"use strict";
 var A;
 (function (A) {
     // collision with 'Origin' var in other part of merged module

tests/baselines/reference/aliasAssignments.js

@@ -14,13 +14,15 @@ y = moduleA; // should be error
 
 
 //// [aliasAssignments_moduleA.js]
+"use strict";
 var someClass = (function () {
     function someClass() {
     }
     return someClass;
 })();
 exports.someClass = someClass;
 //// [aliasAssignments_1.js]
+"use strict";
 var moduleA = require("./aliasAssignments_moduleA");
 var x = moduleA;
 x = 1; // Should be error

tests/baselines/reference/aliasOnMergedModuleInterface.js

@@ -23,6 +23,7 @@ var x: foo.A = foo.bar("hello"); // foo.A should be ok but foo.bar should be err
 
 //// [aliasOnMergedModuleInterface_0.js]
 //// [aliasOnMergedModuleInterface_1.js]
+"use strict";
 var z;
 z.bar("hello"); // This should be ok
 var x = foo.bar("hello"); // foo.A should be ok but foo.bar should be error

tests/baselines/reference/aliasUsageInAccessorsOfClass.js

@@ -28,13 +28,15 @@ class C2 {
 }
 
 //// [aliasUsage1_backbone.js]
+"use strict";
 var Model = (function () {
     function Model() {
     }
     return Model;
 })();
 exports.Model = Model;
 //// [aliasUsage1_moduleA.js]
+"use strict";
 var __extends = (this && this.__extends) || function (d, b) {
     for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
     function __() { this.constructor = d; }
@@ -50,6 +52,7 @@ var VisualizationModel = (function (_super) {
 })(Backbone.Model);
 exports.VisualizationModel = VisualizationModel;
 //// [aliasUsage1_main.js]
+"use strict";
 var moduleA = require("./aliasUsage1_moduleA");
 var C2 = (function () {
     function C2() {

tests/baselines/reference/aliasUsageInArray.js

@@ -22,13 +22,15 @@ var xs: IHasVisualizationModel[] = [moduleA];
 var xs2: typeof moduleA[] = [moduleA];
 
 //// [aliasUsageInArray_backbone.js]
+"use strict";
 var Model = (function () {
     function Model() {
     }
     return Model;
 })();
 exports.Model = Model;
 //// [aliasUsageInArray_moduleA.js]
+"use strict";
 var __extends = (this && this.__extends) || function (d, b) {
     for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
     function __() { this.constructor = d; }
@@ -44,6 +46,7 @@ var VisualizationModel = (function (_super) {
 })(Backbone.Model);
 exports.VisualizationModel = VisualizationModel;
 //// [aliasUsageInArray_main.js]
+"use strict";
 var moduleA = require("./aliasUsageInArray_moduleA");
 var xs = [moduleA];
 var xs2 = [moduleA];

tests/baselines/reference/aliasUsageInFunctionExpression.js

@@ -21,13 +21,15 @@ var f = (x: IHasVisualizationModel) => x;
 f = (x) => moduleA;
 
 //// [aliasUsageInFunctionExpression_backbone.js]
+"use strict";
 var Model = (function () {
     function Model() {
     }
     return Model;
 })();
 exports.Model = Model;
 //// [aliasUsageInFunctionExpression_moduleA.js]
+"use strict";
 var __extends = (this && this.__extends) || function (d, b) {
     for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
     function __() { this.constructor = d; }
@@ -43,6 +45,7 @@ var VisualizationModel = (function (_super) {
 })(Backbone.Model);
 exports.VisualizationModel = VisualizationModel;
 //// [aliasUsageInFunctionExpression_main.js]
+"use strict";
 var moduleA = require("./aliasUsageInFunctionExpression_moduleA");
 var f = function (x) { return x; };
 f = function (x) { return moduleA; };

tests/baselines/reference/aliasUsageInGenericFunction.js

@@ -25,13 +25,15 @@ var r2 = foo({ a: <IHasVisualizationModel>null });
 
 
 //// [aliasUsageInGenericFunction_backbone.js]
+"use strict";
 var Model = (function () {
     function Model() {
     }
     return Model;
 })();
 exports.Model = Model;
 //// [aliasUsageInGenericFunction_moduleA.js]
+"use strict";
 var __extends = (this && this.__extends) || function (d, b) {
     for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
     function __() { this.constructor = d; }
@@ -47,6 +49,7 @@ var VisualizationModel = (function (_super) {
 })(Backbone.Model);
 exports.VisualizationModel = VisualizationModel;
 //// [aliasUsageInGenericFunction_main.js]
+"use strict";
 var moduleA = require("./aliasUsageInGenericFunction_moduleA");
 function foo(x) {
     return x;

tests/baselines/reference/aliasUsageInIndexerOfClass.js

@@ -27,13 +27,15 @@ class N2 {
 }
 
 //// [aliasUsageInIndexerOfClass_backbone.js]
+"use strict";
 var Model = (function () {
     function Model() {
     }
     return Model;
 })();
 exports.Model = Model;
 //// [aliasUsageInIndexerOfClass_moduleA.js]
+"use strict";
 var __extends = (this && this.__extends) || function (d, b) {
     for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
     function __() { this.constructor = d; }
@@ -49,6 +51,7 @@ var VisualizationModel = (function (_super) {
 })(Backbone.Model);
 exports.VisualizationModel = VisualizationModel;
 //// [aliasUsageInIndexerOfClass_main.js]
+"use strict";
 var moduleA = require("./aliasUsageInIndexerOfClass_moduleA");
 var N = (function () {
     function N() {

tests/baselines/reference/aliasUsageInObjectLiteral.js

@@ -22,13 +22,15 @@ var b: { x: IHasVisualizationModel } = { x: moduleA };
 var c: { y: { z: IHasVisualizationModel } } = { y: { z: moduleA } };
 
 //// [aliasUsageInObjectLiteral_backbone.js]
+"use strict";
 var Model = (function () {
     function Model() {
     }
     return Model;
 })();
 exports.Model = Model;
 //// [aliasUsageInObjectLiteral_moduleA.js]
+"use strict";
 var __extends = (this && this.__extends) || function (d, b) {
     for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
     function __() { this.constructor = d; }
@@ -44,6 +46,7 @@ var VisualizationModel = (function (_super) {
 })(Backbone.Model);
 exports.VisualizationModel = VisualizationModel;
 //// [aliasUsageInObjectLiteral_main.js]
+"use strict";
 var moduleA = require("./aliasUsageInObjectLiteral_moduleA");
 var a = { x: moduleA };
 var b = { x: moduleA };

tests/baselines/reference/aliasUsageInOrExpression.js

@@ -25,13 +25,15 @@ var e: { x: IHasVisualizationModel } = <{ x: IHasVisualizationModel }>null || {
 var f: { x: IHasVisualizationModel } = <{ x: IHasVisualizationModel }>null ? { x: moduleA } : null;
 
 //// [aliasUsageInOrExpression_backbone.js]
+"use strict";
 var Model = (function () {
     function Model() {
     }
     return Model;
 })();
 exports.Model = Model;
 //// [aliasUsageInOrExpression_moduleA.js]
+"use strict";
 var __extends = (this && this.__extends) || function (d, b) {
     for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
     function __() { this.constructor = d; }
@@ -47,6 +49,7 @@ var VisualizationModel = (function (_super) {
 })(Backbone.Model);
 exports.VisualizationModel = VisualizationModel;
 //// [aliasUsageInOrExpression_main.js]
+"use strict";
 var moduleA = require("./aliasUsageInOrExpression_moduleA");
 var i;
 var d1 = i || moduleA;

tests/baselines/reference/aliasUsageInTypeArgumentOfExtendsClause.js

@@ -25,13 +25,15 @@ class D extends C<IHasVisualizationModel> {
 }
 
 //// [aliasUsageInTypeArgumentOfExtendsClause_backbone.js]
+"use strict";
 var Model = (function () {
     function Model() {
     }
     return Model;
 })();
 exports.Model = Model;
 //// [aliasUsageInTypeArgumentOfExtendsClause_moduleA.js]
+"use strict";
 var __extends = (this && this.__extends) || function (d, b) {
     for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
     function __() { this.constructor = d; }
@@ -47,6 +49,7 @@ var VisualizationModel = (function (_super) {
 })(Backbone.Model);
 exports.VisualizationModel = VisualizationModel;
 //// [aliasUsageInTypeArgumentOfExtendsClause_main.js]
+"use strict";
 var __extends = (this && this.__extends) || function (d, b) {
     for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
     function __() { this.constructor = d; }

tests/baselines/reference/aliasUsageInVarAssignment.js

@@ -21,13 +21,15 @@ var i: IHasVisualizationModel;
 var m: typeof moduleA = i;
 
 //// [aliasUsageInVarAssignment_backbone.js]
+"use strict";
 var Model = (function () {
     function Model() {
     }
     return Model;
 })();
 exports.Model = Model;
 //// [aliasUsageInVarAssignment_moduleA.js]
+"use strict";
 var __extends = (this && this.__extends) || function (d, b) {
     for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
     function __() { this.constructor = d; }
@@ -43,5 +45,6 @@ var VisualizationModel = (function (_super) {
 })(Backbone.Model);
 exports.VisualizationModel = VisualizationModel;
 //// [aliasUsageInVarAssignment_main.js]
+"use strict";
 var i;
 var m = i;

tests/baselines/reference/aliasUsedAsNameValue.js

@@ -19,10 +19,13 @@ export var a = function () {
 
 
 //// [aliasUsedAsNameValue_0.js]
+"use strict";
 //// [aliasUsedAsNameValue_1.js]
+"use strict";
 function b(a) { return null; }
 exports.b = b;
 //// [aliasUsedAsNameValue_2.js]
+"use strict";
 ///<reference path='aliasUsedAsNameValue_0.ts' />
 ///<reference path='aliasUsedAsNameValue_1.ts' />
 var mod = require("./aliasUsedAsNameValue_0");