Merge pull request #13871 from Microsoft/master-fix13709

[Fix 13709] - Emit __esmodule

Author: yuit

src/compiler/checker.ts

@@ -1,4 +1,4 @@
-/// <reference path="moduleNameResolver.ts"/>
+/// <reference path="moduleNameResolver.ts"/>
 /// <reference path="binder.ts"/>
 
 /* @internal */
@@ -22084,6 +22084,11 @@ namespace ts {
                 }
             }
 
+            if (compilerOptions.module !== ModuleKind.ES2015 && compilerOptions.module !== ModuleKind.System && !compilerOptions.noEmit &&
+                !isInAmbientContext(node.parent.parent) && hasModifier(node.parent.parent, ModifierFlags.Export)) {
+                checkESModuleMarker(node.name);
+            }
+
             const checkLetConstNames = (isLet(node) || isConst(node));
 
             // 1. LexicalDeclaration : LetOrConst BindingList ;
@@ -22096,6 +22101,22 @@ namespace ts {
             return checkLetConstNames && checkGrammarNameInLetOrConstDeclarations(node.name);
         }
 
+        function checkESModuleMarker(name: Identifier | BindingPattern): boolean {
+            if (name.kind === SyntaxKind.Identifier) {
+                if (unescapeIdentifier(name.text) === "__esModule") {
+                    return grammarErrorOnNode(name, Diagnostics.Identifier_expected_esModule_is_reserved_as_an_exported_marker_when_transforming_ECMAScript_modules);
+                }
+            }
+            else {
+                const elements = (<BindingPattern>name).elements;
+                for (const element of elements) {
+                    if (!isOmittedExpression(element)) {
+                        return checkESModuleMarker(element.name);
+                    }
+                }
+            }
+        }
+
         function checkGrammarNameInLetOrConstDeclarations(name: Identifier | BindingPattern): boolean {
             if (name.kind === SyntaxKind.Identifier) {
                 if ((<Identifier>name).originalKeywordKind === SyntaxKind.LetKeyword) {

src/compiler/diagnosticMessages.json

@@ -671,6 +671,10 @@
         "category": "Error",
         "code": 1215
     },
+    "Identifier expected. '__esModule' is reserved as an exported marker when transforming ECMAScript modules.": {
+        "category": "Error",
+        "code": 1216
+    },
     "Export assignment is not supported when '--module' flag is 'system'.": {
         "category": "Error",
         "code": 1218

src/compiler/transformers/module/module.ts

@@ -83,6 +83,11 @@ namespace ts {
 
             const statements: Statement[] = [];
             const statementOffset = addPrologueDirectives(statements, node.statements, /*ensureUseStrict*/ !compilerOptions.noImplicitUseStrict, sourceElementVisitor);
+
+            if (!currentModuleInfo.exportEquals) {
+                append(statements, createUnderscoreUnderscoreESModule());
+            }
+
             append(statements, visitNode(currentModuleInfo.externalHelpersImportDeclaration, sourceElementVisitor, isStatement, /*optional*/ true));
             addRange(statements, visitNodes(node.statements, sourceElementVisitor, isStatement, statementOffset));
             addRange(statements, endLexicalEnvironment());
@@ -92,7 +97,6 @@ namespace ts {
             if (currentModuleInfo.hasExportStarsToExportValues) {
                 addEmitHelper(updated, exportStarHelper);
             }
-
             return updated;
         }
 
@@ -371,6 +375,10 @@ namespace ts {
             const statements: Statement[] = [];
             const statementOffset = addPrologueDirectives(statements, node.statements, /*ensureUseStrict*/ !compilerOptions.noImplicitUseStrict, sourceElementVisitor);
 
+            if (!currentModuleInfo.exportEquals) {
+                append(statements, createUnderscoreUnderscoreESModule());
+            }
+
             // Visit each statement of the module body.
             append(statements, visitNode(currentModuleInfo.externalHelpersImportDeclaration, sourceElementVisitor, isStatement, /*optional*/ true));
             addRange(statements, visitNodes(node.statements, sourceElementVisitor, isStatement, statementOffset));
@@ -665,6 +673,7 @@ namespace ts {
             }
 
             const generatedName = getGeneratedNameForNode(node);
+
             if (node.exportClause) {
                 const statements: Statement[] = [];
                 // export { x, y } from "mod";
@@ -838,6 +847,7 @@ namespace ts {
             let statements: Statement[];
             let variables: VariableDeclaration[];
             let expressions: Expression[];
+
             if (hasModifier(node, ModifierFlags.Export)) {
                 let modifiers: NodeArray<Modifier>;
 
@@ -1127,43 +1137,39 @@ namespace ts {
          * @param allowComments Whether to allow comments on the export.
          */
         function appendExportStatement(statements: Statement[] | undefined, exportName: Identifier, expression: Expression, location?: TextRange, allowComments?: boolean): Statement[] | undefined {
-            if (exportName.text === "default") {
-                const sourceFile = getOriginalNode(currentSourceFile, isSourceFile);
-                if (sourceFile && !sourceFile.symbol.exports.get("___esModule")) {
-                    if (languageVersion === ScriptTarget.ES3) {
-                        statements = append(statements,
-                            createStatement(
-                                createExportExpression(
-                                    createIdentifier("__esModule"),
-                                    createTrue()
-                                )
-                            )
-                        );
-                    }
-                    else {
-                        statements = append(statements,
-                            createStatement(
-                                createCall(
-                                    createPropertyAccess(createIdentifier("Object"), "defineProperty"),
-                                    /*typeArguments*/ undefined,
-                                    [
-                                        createIdentifier("exports"),
-                                        createLiteral("__esModule"),
-                                        createObjectLiteral([
-                                            createPropertyAssignment("value", createTrue())
-                                        ])
-                                    ]
-                                )
-                            )
-                        );
-                    }
-                }
-            }
-
             statements = append(statements, createExportStatement(exportName, expression, location, allowComments));
             return statements;
         }
 
+        function createUnderscoreUnderscoreESModule() {
+            let statement: Statement;
+            if (languageVersion === ScriptTarget.ES3) {
+                statement = createStatement(
+                    createExportExpression(
+                        createIdentifier("__esModule"),
+                        createLiteral(true)
+                    )
+                )
+            }
+            else {
+                statement = createStatement(
+                    createCall(
+                        createPropertyAccess(createIdentifier("Object"), "defineProperty"),
+                        /*typeArguments*/ undefined,
+                        [
+                            createIdentifier("exports"),
+                            createLiteral("__esModule"),
+                            createObjectLiteral([
+                                createPropertyAssignment("value", createLiteral(true))
+                            ])
+                        ]
+                    )
+                );
+            }
+            setEmitFlags(statement, EmitFlags.CustomPrologue);
+            return statement;
+        }
+
         /**
          * Creates a call to the current file's export function to export a value.
          *

src/harness/unittests/compileOnSave.ts

@@ -520,7 +520,7 @@ namespace ts.projectSystem {
 
             const expectedEmittedFileName = "/a/b/f1.js";
             assert.isTrue(host.fileExists(expectedEmittedFileName));
-            assert.equal(host.readFile(expectedEmittedFileName), `"use strict";\r\nfunction Foo() { return 10; }\r\nexports.Foo = Foo;\r\n`);
+            assert.equal(host.readFile(expectedEmittedFileName), `"use strict";\r\nexports.__esModule = true;\r\nfunction Foo() { return 10; }\r\nexports.Foo = Foo;\r\n`);
         });
 
         it("shoud not emit js files in external projects", () => {

tests/baselines/reference/APISample_compile.js

@@ -41,6 +41,7 @@ compile(process.argv.slice(2), {
  *       Please log a "breaking change" issue for any API breaking change affecting this issue
  */
 "use strict";
+exports.__esModule = true;
 var ts = require("typescript");
 function compile(fileNames, options) {
     var program = ts.createProgram(fileNames, options);

tests/baselines/reference/APISample_linter.js

@@ -71,6 +71,7 @@ fileNames.forEach(fileName => {
  *       Please log a "breaking change" issue for any API breaking change affecting this issue
  */
 "use strict";
+exports.__esModule = true;
 var ts = require("typescript");
 function delint(sourceFile) {
     delintNode(sourceFile);

tests/baselines/reference/APISample_parseConfig.js

@@ -43,6 +43,7 @@ export function createProgram(rootFiles: string[], compilerOptionsJson: string):
  *       Please log a "breaking change" issue for any API breaking change affecting this issue
  */
 "use strict";
+exports.__esModule = true;
 var ts = require("typescript");
 function printError(error) {
     if (!error) {

tests/baselines/reference/APISample_transform.js

@@ -23,6 +23,7 @@ console.log(JSON.stringify(result));
  *       Please log a "breaking change" issue for any API breaking change affecting this issue
  */
 "use strict";
+exports.__esModule = true;
 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

@@ -116,6 +116,7 @@ watch(currentDirectoryFiles, { module: ts.ModuleKind.CommonJS });
  *       Please log a "breaking change" issue for any API breaking change affecting this issue
  */
 "use strict";
+exports.__esModule = true;
 var ts = require("typescript");
 function watch(rootFileNames, options) {
     var files = {};

tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedLocalVarsOfTheSameName.js

@@ -31,6 +31,7 @@ export module A {
 
 //// [part1.js]
 "use strict";
+exports.__esModule = true;
 var A;
 (function (A) {
     var Utils;
@@ -44,6 +45,7 @@ var A;
 })(A = exports.A || (exports.A = {}));
 //// [part2.js]
 "use strict";
+exports.__esModule = true;
 var A;
 (function (A) {
     // collision with 'Origin' var in other part of merged module