From 86d561d2bea592d329944d4f869e27501544f684 Mon Sep 17 00:00:00 2001
From: Mohamed Hegazy <mhegazy@microsoft.com>
Date: Mon, 23 Mar 2015 11:17:40 -0700
Subject: [PATCH] Check for instantiation on export default in ES6

---
 src/compiler/emitter.ts                       | 40 ++++++++++---------
 .../reference/es6ExportAssignment.js          |  1 -
 tests/baselines/reference/es6ExportEquals.js  |  1 -
 .../reference/es6ImportEqualsDeclaration.js   |  1 -
 .../es6ImportNamedImportInExportAssignment.js |  1 -
 .../exportDefaultForNonInstantiatedModule.js  | 10 +++++
 ...xportDefaultForNonInstantiatedModule.types | 13 ++++++
 .../exportDefaultForNonInstantiatedModule.ts  |  8 ++++
 8 files changed, 52 insertions(+), 23 deletions(-)
 create mode 100644 tests/baselines/reference/exportDefaultForNonInstantiatedModule.js
 create mode 100644 tests/baselines/reference/exportDefaultForNonInstantiatedModule.types
 create mode 100644 tests/cases/compiler/exportDefaultForNonInstantiatedModule.ts

diff --git a/src/compiler/emitter.ts b/src/compiler/emitter.ts
index 9ddd690b96f..9a82e69c3fa 100644
--- a/src/compiler/emitter.ts
+++ b/src/compiler/emitter.ts
@@ -3924,26 +3924,28 @@ module ts {
             }
 
             function emitExportAssignment(node: ExportAssignment) {
-                if (languageVersion >= ScriptTarget.ES6) {
-                    writeLine();
-                    emitStart(node);
-                    write("export default ");
-                    var expression = node.expression;
-                    emit(expression);
-                    if (expression.kind !== SyntaxKind.FunctionDeclaration &&
-                        expression.kind !== SyntaxKind.ClassDeclaration) {
-                        write(";");
+                if (!node.isExportEquals && resolver.isValueAliasDeclaration(node)) {
+                    if (languageVersion >= ScriptTarget.ES6) {
+                        writeLine();
+                        emitStart(node);
+                        write("export default ");
+                        var expression = node.expression;
+                        emit(expression);
+                        if (expression.kind !== SyntaxKind.FunctionDeclaration &&
+                            expression.kind !== SyntaxKind.ClassDeclaration) {
+                            write(";");
+                        }
+                        emitEnd(node);
+                    }
+                    else {
+                        writeLine();
+                        emitStart(node);
+                        emitContainingModuleName(node);
+                        write(".default = ");
+                        emit(node.expression);
+                        write(";");
+                        emitEnd(node);
                     }
-                    emitEnd(node);
-                }
-                else if (!node.isExportEquals && resolver.isValueAliasDeclaration(node)) {
-                    writeLine();
-                    emitStart(node);
-                    emitContainingModuleName(node);
-                    write(".default = ");
-                    emit(node.expression);
-                    write(";");
-                    emitEnd(node);
                 }
             }
 
diff --git a/tests/baselines/reference/es6ExportAssignment.js b/tests/baselines/reference/es6ExportAssignment.js
index 113e28108b1..4a4e0368bb7 100644
--- a/tests/baselines/reference/es6ExportAssignment.js
+++ b/tests/baselines/reference/es6ExportAssignment.js
@@ -5,4 +5,3 @@ export = a;
 
 //// [es6ExportAssignment.js]
 var a = 10;
-export default a;
diff --git a/tests/baselines/reference/es6ExportEquals.js b/tests/baselines/reference/es6ExportEquals.js
index d51f8740da0..68c5788c89b 100644
--- a/tests/baselines/reference/es6ExportEquals.js
+++ b/tests/baselines/reference/es6ExportEquals.js
@@ -8,7 +8,6 @@ export = f;
 //// [es6ExportEquals.js]
 export function f() {
 }
-export default f;
 
 
 //// [es6ExportEquals.d.ts]
diff --git a/tests/baselines/reference/es6ImportEqualsDeclaration.js b/tests/baselines/reference/es6ImportEqualsDeclaration.js
index b8e9777a894..5195bdc631b 100644
--- a/tests/baselines/reference/es6ImportEqualsDeclaration.js
+++ b/tests/baselines/reference/es6ImportEqualsDeclaration.js
@@ -10,5 +10,4 @@ import a = require("server");
 
 //// [server.js]
 var a = 10;
-export default a;
 //// [client.js]
diff --git a/tests/baselines/reference/es6ImportNamedImportInExportAssignment.js b/tests/baselines/reference/es6ImportNamedImportInExportAssignment.js
index ea9e65db34a..eab345e4e7f 100644
--- a/tests/baselines/reference/es6ImportNamedImportInExportAssignment.js
+++ b/tests/baselines/reference/es6ImportNamedImportInExportAssignment.js
@@ -12,7 +12,6 @@ export = a;
 export var a = 10;
 //// [es6ImportNamedImportInExportAssignment_1.js]
 import { a } from "es6ImportNamedImportInExportAssignment_0";
-export default a;
 
 
 //// [es6ImportNamedImportInExportAssignment_0.d.ts]
diff --git a/tests/baselines/reference/exportDefaultForNonInstantiatedModule.js b/tests/baselines/reference/exportDefaultForNonInstantiatedModule.js
new file mode 100644
index 00000000000..f2b98e6eb44
--- /dev/null
+++ b/tests/baselines/reference/exportDefaultForNonInstantiatedModule.js
@@ -0,0 +1,10 @@
+//// [exportDefaultForNonInstantiatedModule.ts]
+
+module m {
+    export interface foo {
+    }
+}
+// Should not be emitted
+export default m;
+
+//// [exportDefaultForNonInstantiatedModule.js]
diff --git a/tests/baselines/reference/exportDefaultForNonInstantiatedModule.types b/tests/baselines/reference/exportDefaultForNonInstantiatedModule.types
new file mode 100644
index 00000000000..940bb44658e
--- /dev/null
+++ b/tests/baselines/reference/exportDefaultForNonInstantiatedModule.types
@@ -0,0 +1,13 @@
+=== tests/cases/compiler/exportDefaultForNonInstantiatedModule.ts ===
+
+module m {
+>m : unknown
+
+    export interface foo {
+>foo : foo
+    }
+}
+// Should not be emitted
+export default m;
+>m : unknown
+
diff --git a/tests/cases/compiler/exportDefaultForNonInstantiatedModule.ts b/tests/cases/compiler/exportDefaultForNonInstantiatedModule.ts
new file mode 100644
index 00000000000..a1d1cab94b6
--- /dev/null
+++ b/tests/cases/compiler/exportDefaultForNonInstantiatedModule.ts
@@ -0,0 +1,8 @@
+// @target: ES6
+
+module m {
+    export interface foo {
+    }
+}
+// Should not be emitted
+export default m;
\ No newline at end of file