Emit export default in ES6

src/compiler/checker.ts

@@ -9946,7 +9946,7 @@ module ts {
             }
             checkExternalModuleExports(container);
 
-            if (languageVersion >= ScriptTarget.ES6) {
+            if (node.isExportEquals && languageVersion >= ScriptTarget.ES6) {
                 // export assignment is deprecated in es6 or above
                 grammarErrorOnNode(node, Diagnostics.Export_assignment_cannot_be_used_when_targeting_ECMAScript_6_or_higher_Consider_using_export_default_instead);
             }
@@ -9994,7 +9994,7 @@ module ts {
             if (!links.exportsChecked) {
                 var defaultSymbol = getExportAssignmentSymbol(moduleSymbol);
                 if (defaultSymbol) {
-                    if (hasExportedMembers(moduleSymbol)) {
+                    if (languageVersion < ScriptTarget.ES6 && hasExportedMembers(moduleSymbol)) {
                         var declaration = getDeclarationOfAliasSymbol(defaultSymbol) || defaultSymbol.valueDeclaration;
                         error(declaration, Diagnostics.An_export_assignment_cannot_be_used_in_a_module_with_other_exported_elements);
                     }

src/compiler/emitter.ts

@@ -4331,6 +4331,19 @@ module ts {
                 }
             }
 
+            function shouldEmitFunctionName(node: Declaration): boolean {
+                // Emit a declaration name for the function iff:
+                //    it is a function expression with a name provided
+                //    it is a function declaration with a name provided
+                //    it is a function declaration is not the default export, and is missing a name (emit a generated name for it)
+                if (node.kind === SyntaxKind.FunctionExpression) {
+                    return !!node.name;
+                }
+                else if (node.kind === SyntaxKind.FunctionDeclaration) {
+                    return !!node.name || (languageVersion >= ScriptTarget.ES6 && !(node.flags & NodeFlags.Default));
+                }
+            }
+
             function emitFunctionDeclaration(node: FunctionLikeDeclaration) {
                 if (nodeIsMissing(node.body)) {
                     return emitPinnedOrTripleSlashComments(node);
@@ -4346,13 +4359,17 @@ module ts {
                 if (!shouldEmitAsArrowFunction(node)) {
                     if (isES6ModuleMemberDeclaration(node)) {
                         write("export ");
+                        if (node.flags & NodeFlags.Default) {
+                            write("default ");
+                        }
                     }
                     write("function ");
                 }
 
-                if (node.kind === SyntaxKind.FunctionDeclaration || (node.kind === SyntaxKind.FunctionExpression && node.name)) {
+                if (shouldEmitFunctionName(node)) {
                     emitDeclarationName(node);
                 }
+
                 emitSignatureAndBody(node);
                 if (languageVersion < ScriptTarget.ES6 && node.kind === SyntaxKind.FunctionDeclaration && node.parent === currentSourceFile && node.name) {
                     emitExportMemberAssignments((<FunctionDeclaration>node).name);
@@ -5412,6 +5429,7 @@ module ts {
             }
 
             function emitES6Module(node: SourceFile, startIndex: number) {
+                createExternalModuleInfo(node);
                 externalImports = undefined;
                 exportSpecifiers = undefined;
                 emitCaptureThisForNodeIfNecessary(node);
@@ -5422,20 +5440,37 @@ module ts {
 
             function emitExportDefault(sourceFile: SourceFile, emitAsReturn: boolean) {
                 if (exportDefault && resolver.hasExportDefaultValue(sourceFile)) {
-                    writeLine();
-                    emitStart(exportDefault);
-                    write(emitAsReturn ? "return " : "module.exports = ");
-                    if (exportDefault.kind === SyntaxKind.ExportAssignment) {
-                        emit((<ExportAssignment>exportDefault).expression);
-                    }
-                    else if (exportDefault.kind === SyntaxKind.ExportSpecifier) {
-                        emit((<ExportSpecifier>exportDefault).propertyName);
+                    if (languageVersion >= ScriptTarget.ES6) {
+                        Debug.assert(!emitAsReturn);
+                        if (exportDefault.kind === SyntaxKind.ExportAssignment) {
+                            writeLine();
+                            emitStart(exportDefault);
+                            write("export default ");
+                            var expression = (<ExportAssignment>exportDefault).expression;
+                            emit(expression);
+                            if (expression.kind !== SyntaxKind.FunctionDeclaration &&
+                                expression.kind !== SyntaxKind.ClassDeclaration) {
+                                write(";");
+                            }
+                            emitEnd(exportDefault);
+                        }
                     }
                     else {
-                        emitDeclarationName(<Declaration>exportDefault);
+                        writeLine();
+                        emitStart(exportDefault);
+                        write(emitAsReturn ? "return " : "module.exports = ");
+                        if (exportDefault.kind === SyntaxKind.ExportAssignment) {
+                            emit((<ExportAssignment>exportDefault).expression);
+                        }
+                        else if (exportDefault.kind === SyntaxKind.ExportSpecifier) {
+                            emit((<ExportSpecifier>exportDefault).propertyName);
+                        }
+                        else {
+                            emitDeclarationName(<Declaration>exportDefault);
+                        }
+                        write(";");
+                        emitEnd(exportDefault);
                     }
-                    write(";");
-                    emitEnd(exportDefault);
                 }
             }
 

tests/baselines/reference/es5ExportDefaultClassDeclaration.js

@@ -0,0 +1,22 @@
+//// [es5ExportDefaultClassDeclaration.ts]
+
+export default class C {
+    method() { }
+}
+
+
+//// [es5ExportDefaultClassDeclaration.js]
+var C = (function () {
+    function C() {
+    }
+    C.prototype.method = function () {
+    };
+    return C;
+})();
+module.exports = C;
+
+
+//// [es5ExportDefaultClassDeclaration.d.ts]
+export declare class C {
+    method(): void;
+}

tests/baselines/reference/es5ExportDefaultClassDeclaration.types

@@ -0,0 +1,9 @@
+=== tests/cases/compiler/es5ExportDefaultClassDeclaration.ts ===
+
+export default class C {
+>C : C
+
+    method() { }
+>method : () => void
+}
+

tests/baselines/reference/es5ExportDefaultClassDeclaration2.js

@@ -0,0 +1,52 @@
+//// [es5ExportDefaultClassDeclaration2.ts]
+
+export default class {
+    method() { }
+}
+
+
+//// [es5ExportDefaultClassDeclaration2.js]
+var _default = (function () {
+    function _default() {
+    }
+    _default.prototype.method = function () {
+    };
+    return _default;
+})();
+module.exports = _default;
+
+
+//// [es5ExportDefaultClassDeclaration2.d.ts]
+export declare class  {
+    method(): void;
+}
+
+
+//// [DtsFileErrors]
+
+
+tests/cases/compiler/es5ExportDefaultClassDeclaration2.d.ts(1,1): error TS1128: Declaration or statement expected.
+tests/cases/compiler/es5ExportDefaultClassDeclaration2.d.ts(1,8): error TS2304: Cannot find name 'declare'.
+tests/cases/compiler/es5ExportDefaultClassDeclaration2.d.ts(1,16): error TS1005: ';' expected.
+tests/cases/compiler/es5ExportDefaultClassDeclaration2.d.ts(2,5): error TS2304: Cannot find name 'method'.
+tests/cases/compiler/es5ExportDefaultClassDeclaration2.d.ts(2,13): error TS1005: ';' expected.
+tests/cases/compiler/es5ExportDefaultClassDeclaration2.d.ts(2,19): error TS1109: Expression expected.
+
+
+==== tests/cases/compiler/es5ExportDefaultClassDeclaration2.d.ts (6 errors) ====
+    export declare class  {
+    ~~~~~~
+!!! error TS1128: Declaration or statement expected.
+           ~~~~~~~
+!!! error TS2304: Cannot find name 'declare'.
+                   ~~~~~
+!!! error TS1005: ';' expected.
+        method(): void;
+        ~~~~~~
+!!! error TS2304: Cannot find name 'method'.
+                ~
+!!! error TS1005: ';' expected.
+                      ~
+!!! error TS1109: Expression expected.
+    }
+    

tests/baselines/reference/es5ExportDefaultClassDeclaration2.types

@@ -0,0 +1,7 @@
+=== tests/cases/compiler/es5ExportDefaultClassDeclaration2.ts ===
+
+export default class {
+    method() { }
+>method : () => void
+}
+

tests/baselines/reference/es5ExportDefaultExpression.js

@@ -0,0 +1,11 @@
+//// [es5ExportDefaultExpression.ts]
+
+export default (1 + 2);
+
+
+//// [es5ExportDefaultExpression.js]
+module.exports = (1 + 2);
+
+
+//// [es5ExportDefaultExpression.d.ts]
+export default (1 + 2);

tests/baselines/reference/es5ExportDefaultExpression.types

@@ -0,0 +1,6 @@
+=== tests/cases/compiler/es5ExportDefaultExpression.ts ===
+
+export default (1 + 2);
+>(1 + 2) : number
+>1 + 2 : number
+

tests/baselines/reference/es5ExportDefaultFunctionDeclaration.js

@@ -0,0 +1,13 @@
+//// [es5ExportDefaultFunctionDeclaration.ts]
+
+export default function f() { }
+
+
+//// [es5ExportDefaultFunctionDeclaration.js]
+function f() {
+}
+module.exports = f;
+
+
+//// [es5ExportDefaultFunctionDeclaration.d.ts]
+export declare function f(): void;

tests/baselines/reference/es5ExportDefaultFunctionDeclaration.types

@@ -0,0 +1,5 @@
+=== tests/cases/compiler/es5ExportDefaultFunctionDeclaration.ts ===
+
+export default function f() { }
+>f : () => void
+

tests/baselines/reference/es5ExportDefaultFunctionDeclaration2.js

@@ -0,0 +1,26 @@
+//// [es5ExportDefaultFunctionDeclaration2.ts]
+
+export default function () { }
+
+
+//// [es5ExportDefaultFunctionDeclaration2.js]
+function () {
+}
+module.exports = _default;
+
+
+//// [es5ExportDefaultFunctionDeclaration2.d.ts]
+export declare function (): void;
+
+
+//// [DtsFileErrors]
+
+
+tests/cases/compiler/es5ExportDefaultFunctionDeclaration2.d.ts(1,25): error TS1003: Identifier expected.
+
+
+==== tests/cases/compiler/es5ExportDefaultFunctionDeclaration2.d.ts (1 errors) ====
+    export declare function (): void;
+                            ~
+!!! error TS1003: Identifier expected.
+    

tests/baselines/reference/es5ExportDefaultFunctionDeclaration2.types

@@ -0,0 +1,5 @@
+=== tests/cases/compiler/es5ExportDefaultFunctionDeclaration2.ts ===
+
+No type information for this code.export default function () { }
+No type information for this code.
+No type information for this code.

tests/baselines/reference/es5ExportDefaultIdentifier.errors.txt

@@ -0,0 +1,11 @@
+tests/cases/compiler/es5ExportDefaultIdentifier.ts(4,1): error TS2309: An export assignment cannot be used in a module with other exported elements.
+
+
+==== tests/cases/compiler/es5ExportDefaultIdentifier.ts (1 errors) ====
+    
+    export function f() { }
+    
+    export default f;
+    ~~~~~~~~~~~~~~~~~
+!!! error TS2309: An export assignment cannot be used in a module with other exported elements.
+    

tests/baselines/reference/es5ExportDefaultIdentifier.js

@@ -0,0 +1,17 @@
+//// [es5ExportDefaultIdentifier.ts]
+
+export function f() { }
+
+export default f;
+
+
+//// [es5ExportDefaultIdentifier.js]
+function f() {
+}
+exports.f = f;
+module.exports = f;
+
+
+//// [es5ExportDefaultIdentifier.d.ts]
+export declare function f(): void;
+export default f;

tests/baselines/reference/es5ExportEquals.errors.txt

@@ -0,0 +1,11 @@
+tests/cases/compiler/es5ExportEquals.ts(4,1): error TS2309: An export assignment cannot be used in a module with other exported elements.
+
+
+==== tests/cases/compiler/es5ExportEquals.ts (1 errors) ====
+    
+    export function f() { }
+    
+    export = f;
+    ~~~~~~~~~~~
+!!! error TS2309: An export assignment cannot be used in a module with other exported elements.
+    

tests/baselines/reference/es5ExportEquals.js

@@ -0,0 +1,17 @@
+//// [es5ExportEquals.ts]
+
+export function f() { }
+
+export = f;
+
+
+//// [es5ExportEquals.js]
+function f() {
+}
+exports.f = f;
+module.exports = f;
+
+
+//// [es5ExportEquals.d.ts]
+export declare function f(): void;
+export = f;

tests/baselines/reference/es6ExportAssignment.js

@@ -5,3 +5,4 @@ export = a;
 
 //// [es6ExportAssignment.js]
 var a = 10;
+export default a;

tests/baselines/reference/es6ExportDefaultClassDeclaration.js

@@ -0,0 +1,22 @@
+//// [es6ExportDefaultClassDeclaration.ts]
+
+export default class C {
+    method() { }
+}
+
+
+//// [es6ExportDefaultClassDeclaration.js]
+var C = (function () {
+    function C() {
+    }
+    C.prototype.method = function () {
+    };
+    return C;
+})();
+export { C };
+
+
+//// [es6ExportDefaultClassDeclaration.d.ts]
+export declare class C {
+    method(): void;
+}

tests/baselines/reference/es6ExportDefaultClassDeclaration.types

@@ -0,0 +1,9 @@
+=== tests/cases/compiler/es6ExportDefaultClassDeclaration.ts ===
+
+export default class C {
+>C : C
+
+    method() { }
+>method : () => void
+}
+

tests/baselines/reference/es6ExportDefaultClassDeclaration2.js

@@ -0,0 +1,52 @@
+//// [es6ExportDefaultClassDeclaration2.ts]
+
+export default class {
+    method() { }
+}
+
+
+//// [es6ExportDefaultClassDeclaration2.js]
+var _default = (function () {
+    function _default() {
+    }
+    _default.prototype.method = function () {
+    };
+    return _default;
+})();
+export {  };
+
+
+//// [es6ExportDefaultClassDeclaration2.d.ts]
+export declare class  {
+    method(): void;
+}
+
+
+//// [DtsFileErrors]
+
+
+tests/cases/compiler/es6ExportDefaultClassDeclaration2.d.ts(1,1): error TS1128: Declaration or statement expected.
+tests/cases/compiler/es6ExportDefaultClassDeclaration2.d.ts(1,8): error TS2304: Cannot find name 'declare'.
+tests/cases/compiler/es6ExportDefaultClassDeclaration2.d.ts(1,16): error TS1005: ';' expected.
+tests/cases/compiler/es6ExportDefaultClassDeclaration2.d.ts(2,5): error TS2304: Cannot find name 'method'.
+tests/cases/compiler/es6ExportDefaultClassDeclaration2.d.ts(2,13): error TS1005: ';' expected.
+tests/cases/compiler/es6ExportDefaultClassDeclaration2.d.ts(2,19): error TS1109: Expression expected.
+
+
+==== tests/cases/compiler/es6ExportDefaultClassDeclaration2.d.ts (6 errors) ====
+    export declare class  {
+    ~~~~~~
+!!! error TS1128: Declaration or statement expected.
+           ~~~~~~~
+!!! error TS2304: Cannot find name 'declare'.
+                   ~~~~~
+!!! error TS1005: ';' expected.
+        method(): void;
+        ~~~~~~
+!!! error TS2304: Cannot find name 'method'.
+                ~
+!!! error TS1005: ';' expected.
+                      ~
+!!! error TS1109: Expression expected.
+    }
+    

tests/baselines/reference/es6ExportDefaultClassDeclaration2.types

@@ -0,0 +1,7 @@
+=== tests/cases/compiler/es6ExportDefaultClassDeclaration2.ts ===
+
+export default class {
+    method() { }
+>method : () => void
+}
+

tests/baselines/reference/es6ExportDefaultExpression.js

@@ -0,0 +1,11 @@
+//// [es6ExportDefaultExpression.ts]
+
+export default (1 + 2);
+
+
+//// [es6ExportDefaultExpression.js]
+export default (1 + 2);
+
+
+//// [es6ExportDefaultExpression.d.ts]
+export default (1 + 2);

tests/baselines/reference/es6ExportDefaultExpression.types

@@ -0,0 +1,6 @@
+=== tests/cases/compiler/es6ExportDefaultExpression.ts ===
+
+export default (1 + 2);
+>(1 + 2) : number
+>1 + 2 : number
+

tests/baselines/reference/es6ExportDefaultFunctionDeclaration.js

@@ -0,0 +1,12 @@
+//// [es6ExportDefaultFunctionDeclaration.ts]
+
+export default function f() { }
+
+
+//// [es6ExportDefaultFunctionDeclaration.js]
+export default function f() {
+}
+
+
+//// [es6ExportDefaultFunctionDeclaration.d.ts]
+export declare function f(): void;

tests/baselines/reference/es6ExportDefaultFunctionDeclaration.types

@@ -0,0 +1,5 @@
+=== tests/cases/compiler/es6ExportDefaultFunctionDeclaration.ts ===
+
+export default function f() { }
+>f : () => void
+

tests/baselines/reference/es6ExportDefaultFunctionDeclaration2.js

@@ -0,0 +1,25 @@
+//// [es6ExportDefaultFunctionDeclaration2.ts]
+
+export default function () { }
+
+
+//// [es6ExportDefaultFunctionDeclaration2.js]
+export default function () {
+}
+
+
+//// [es6ExportDefaultFunctionDeclaration2.d.ts]
+export declare function (): void;
+
+
+//// [DtsFileErrors]
+
+
+tests/cases/compiler/es6ExportDefaultFunctionDeclaration2.d.ts(1,25): error TS1003: Identifier expected.
+
+
+==== tests/cases/compiler/es6ExportDefaultFunctionDeclaration2.d.ts (1 errors) ====
+    export declare function (): void;
+                            ~
+!!! error TS1003: Identifier expected.
+    

tests/baselines/reference/es6ExportDefaultFunctionDeclaration2.types

@@ -0,0 +1,5 @@
+=== tests/cases/compiler/es6ExportDefaultFunctionDeclaration2.ts ===
+
+No type information for this code.export default function () { }
+No type information for this code.
+No type information for this code.

tests/baselines/reference/es6ExportDefaultIdentifier.js

@@ -0,0 +1,16 @@
+//// [es6ExportDefaultIdentifier.ts]
+
+export function f() { }
+
+export default f;
+
+
+//// [es6ExportDefaultIdentifier.js]
+export function f() {
+}
+export default f;
+
+
+//// [es6ExportDefaultIdentifier.d.ts]
+export declare function f(): void;
+export default f;

tests/baselines/reference/es6ExportDefaultIdentifier.types

@@ -0,0 +1,8 @@
+=== tests/cases/compiler/es6ExportDefaultIdentifier.ts ===
+
+export function f() { }
+>f : () => void
+
+export default f;
+>f : () => void
+

tests/baselines/reference/es6ExportEquals.errors.txt

@@ -0,0 +1,11 @@
+tests/cases/compiler/es6ExportEquals.ts(4,1): error TS1201: Export assignment cannot be used when targeting ECMAScript 6 or higher. Consider using 'export default' instead.
+
+
+==== tests/cases/compiler/es6ExportEquals.ts (1 errors) ====
+    
+    export function f() { }
+    
+    export = f;
+    ~~~~~~~~~~~
+!!! error TS1201: Export assignment cannot be used when targeting ECMAScript 6 or higher. Consider using 'export default' instead.
+    

tests/baselines/reference/es6ExportEquals.js

@@ -0,0 +1,16 @@
+//// [es6ExportEquals.ts]
+
+export function f() { }
+
+export = f;
+
+
+//// [es6ExportEquals.js]
+export function f() {
+}
+export default f;
+
+
+//// [es6ExportEquals.d.ts]
+export declare function f(): void;
+export = f;

tests/baselines/reference/es6ImportDefaultBindingFollowedWithNamedImport1.js

@@ -22,6 +22,7 @@ var x1: number = defaultBinding6;
 
 //// [es6ImportDefaultBindingFollowedWithNamedImport1_0.js]
 var a = 10;
+export default a;
 //// [es6ImportDefaultBindingFollowedWithNamedImport1_1.js]
 import defaultBinding1 from "es6ImportDefaultBindingFollowedWithNamedImport1_0";
 var x1 = defaultBinding1;

tests/baselines/reference/es6ImportDefaultBindingFollowedWithNamespaceBinding1.js

@@ -11,6 +11,7 @@ var x: number = defaultBinding;
 
 //// [es6ImportDefaultBindingFollowedWithNamespaceBinding_0.js]
 var a = 10;
+export default a;
 //// [es6ImportDefaultBindingFollowedWithNamespaceBinding_1.js]
 import defaultBinding from "es6ImportDefaultBindingFollowedWithNamespaceBinding_0";
 var x = defaultBinding;

tests/baselines/reference/es6ImportEqualsDeclaration.js

@@ -10,4 +10,5 @@ import a = require("server");
 
 //// [server.js]
 var a = 10;
+export default a;
 //// [client.js]

tests/cases/compiler/es5ExportDefaultClassDeclaration.ts

@@ -0,0 +1,7 @@
+// @target: es5
+// @module: commonjs
+// @declaration: true
+
+export default class C {
+    method() { }
+}

tests/cases/compiler/es5ExportDefaultClassDeclaration2.ts

@@ -0,0 +1,7 @@
+// @target: es5
+// @module: commonjs
+// @declaration: true
+
+export default class {
+    method() { }
+}

tests/cases/compiler/es5ExportDefaultExpression.ts

@@ -0,0 +1,5 @@
+// @target: es5
+// @module: commonjs
+// @declaration: true
+
+export default (1 + 2);

tests/cases/compiler/es5ExportDefaultFunctionDeclaration.ts

@@ -0,0 +1,5 @@
+// @target: es5
+// @module: commonjs
+// @declaration: true
+
+export default function f() { }

tests/cases/compiler/es5ExportDefaultFunctionDeclaration2.ts

@@ -0,0 +1,5 @@
+// @target: es5
+// @module: commonjs
+// @declaration: true
+
+export default function () { }

tests/cases/compiler/es5ExportDefaultIdentifier.ts

@@ -0,0 +1,7 @@
+// @target: es5
+// @module: commonjs
+// @declaration: true
+
+export function f() { }
+
+export default f;

tests/cases/compiler/es5ExportEquals.ts

@@ -0,0 +1,7 @@
+// @target: es5
+// @module: commonjs
+// @declaration: true
+
+export function f() { }
+
+export = f;

tests/cases/compiler/es6ExportDefaultClassDeclaration.ts

@@ -0,0 +1,6 @@
+// @target: es6
+// @declaration: true
+
+export default class C {
+    method() { }
+}

tests/cases/compiler/es6ExportDefaultClassDeclaration2.ts

@@ -0,0 +1,6 @@
+// @target: es6
+// @declaration: true
+
+export default class {
+    method() { }
+}

tests/cases/compiler/es6ExportDefaultExpression.ts

@@ -0,0 +1,4 @@
+// @target: es6
+// @declaration: true
+
+export default (1 + 2);

tests/cases/compiler/es6ExportDefaultFunctionDeclaration.ts

@@ -0,0 +1,4 @@
+// @target: es6
+// @declaration: true
+
+export default function f() { }

tests/cases/compiler/es6ExportDefaultFunctionDeclaration2.ts

@@ -0,0 +1,4 @@
+// @target: es6
+// @declaration: true
+
+export default function () { }

tests/cases/compiler/es6ExportDefaultIdentifier.ts

@@ -0,0 +1,6 @@
+// @target: es6
+// @declaration: true
+
+export function f() { }
+
+export default f;

tests/cases/compiler/es6ExportEquals.ts

@@ -0,0 +1,6 @@
+// @target: es6
+// @declaration: true
+
+export function f() { }
+
+export = f;