From 42d61b5098ac5847b5e09117cf92092c6dc9f284 Mon Sep 17 00:00:00 2001
From: Kanchalai Tanglertsampan <yuisu@microsoft.com>
Date: Mon, 8 Aug 2016 11:55:59 -0700
Subject: [PATCH 1/9] Call checkExpression eventhough there is no appropriate
 type from destructuring of array

---
 src/compiler/checker.ts | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 4ead19f7c48..74a1e17bd6b 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -4447,9 +4447,14 @@ namespace ts {
             return property;
         }
 
-        // Return the symbol for the property with the given name in the given type. Creates synthetic union properties when
-        // necessary, maps primitive types and type parameters are to their apparent types, and augments with properties from
-        // Object and Function as appropriate.
+        /**
+         * Return the symbol for the property with the given name in the given type. Creates synthetic union properties when
+         * necessary, maps primitive types and type parameters are to their apparent types, and augments with properties from
+         * Object and Function as appropriate.
+         *
+         * @param type a type to look up property from
+         * @param name a name of property to look up in a given type
+         */
         function getPropertyOfType(type: Type, name: string): Symbol {
             type = getApparentType(type);
             if (type.flags & TypeFlags.ObjectType) {
@@ -12856,6 +12861,9 @@ namespace ts {
                         return checkDestructuringAssignment(element, type, contextualMapper);
                     }
                     else {
+                        // We still need to check element expression here because we may need to set appropriate flag on the expression
+                        // such as NodeCheckFlags.LexicalThis on "this"expression.
+                        checkExpression(element);
                         if (isTupleType(sourceType)) {
                             error(element, Diagnostics.Tuple_type_0_with_length_1_cannot_be_assigned_to_tuple_with_length_2, typeToString(sourceType), (<TupleType>sourceType).elementTypes.length, elements.length);
                         }

From 9a18429184a42f6a34a963908acdc141245d1ade Mon Sep 17 00:00:00 2001
From: Kanchalai Tanglertsampan <yuisu@microsoft.com>
Date: Mon, 8 Aug 2016 11:56:20 -0700
Subject: [PATCH 2/9] Add tests and baselines

---
 ...turingThisInTupleDestructuring1.errors.txt | 13 +++++++++++
 .../emitCapturingThisInTupleDestructuring1.js | 11 +++++++++
 ...turingThisInTupleDestructuring2.errors.txt | 16 +++++++++++++
 .../emitCapturingThisInTupleDestructuring2.js | 23 +++++++++++++++++++
 .../emitCapturingThisInTupleDestructuring1.ts |  4 ++++
 .../emitCapturingThisInTupleDestructuring2.ts | 10 ++++++++
 6 files changed, 77 insertions(+)
 create mode 100644 tests/baselines/reference/emitCapturingThisInTupleDestructuring1.errors.txt
 create mode 100644 tests/baselines/reference/emitCapturingThisInTupleDestructuring1.js
 create mode 100644 tests/baselines/reference/emitCapturingThisInTupleDestructuring2.errors.txt
 create mode 100644 tests/baselines/reference/emitCapturingThisInTupleDestructuring2.js
 create mode 100644 tests/cases/compiler/emitCapturingThisInTupleDestructuring1.ts
 create mode 100644 tests/cases/compiler/emitCapturingThisInTupleDestructuring2.ts

diff --git a/tests/baselines/reference/emitCapturingThisInTupleDestructuring1.errors.txt b/tests/baselines/reference/emitCapturingThisInTupleDestructuring1.errors.txt
new file mode 100644
index 00000000000..d0f11d056ca
--- /dev/null
+++ b/tests/baselines/reference/emitCapturingThisInTupleDestructuring1.errors.txt
@@ -0,0 +1,13 @@
+tests/cases/compiler/emitCapturingThisInTupleDestructuring1.ts(3,17): error TS2493: Tuple type '[any]' with length '1' cannot be assigned to tuple with length '3'.
+tests/cases/compiler/emitCapturingThisInTupleDestructuring1.ts(3,29): error TS2493: Tuple type '[any]' with length '1' cannot be assigned to tuple with length '3'.
+
+
+==== tests/cases/compiler/emitCapturingThisInTupleDestructuring1.ts (2 errors) ====
+    declare function wrapper(x: any);
+    wrapper((array: [any]) => {
+        [this.test, this.test1, this.test2] = array;  // even though there is a compiler error, we should still emit lexical capture for "this"
+                    ~~~~~~~~~~
+!!! error TS2493: Tuple type '[any]' with length '1' cannot be assigned to tuple with length '3'.
+                                ~~~~~~~~~~
+!!! error TS2493: Tuple type '[any]' with length '1' cannot be assigned to tuple with length '3'.
+    });
\ No newline at end of file
diff --git a/tests/baselines/reference/emitCapturingThisInTupleDestructuring1.js b/tests/baselines/reference/emitCapturingThisInTupleDestructuring1.js
new file mode 100644
index 00000000000..9dd7453ba4f
--- /dev/null
+++ b/tests/baselines/reference/emitCapturingThisInTupleDestructuring1.js
@@ -0,0 +1,11 @@
+//// [emitCapturingThisInTupleDestructuring1.ts]
+declare function wrapper(x: any);
+wrapper((array: [any]) => {
+    [this.test, this.test1, this.test2] = array;  // even though there is a compiler error, we should still emit lexical capture for "this"
+});
+
+//// [emitCapturingThisInTupleDestructuring1.js]
+var _this = this;
+wrapper(function (array) {
+    _this.test = array[0], _this.test1 = array[1], _this.test2 = array[2]; // even though there is a compiler error, we should still emit lexical capture for "this"
+});
diff --git a/tests/baselines/reference/emitCapturingThisInTupleDestructuring2.errors.txt b/tests/baselines/reference/emitCapturingThisInTupleDestructuring2.errors.txt
new file mode 100644
index 00000000000..25207e28c79
--- /dev/null
+++ b/tests/baselines/reference/emitCapturingThisInTupleDestructuring2.errors.txt
@@ -0,0 +1,16 @@
+tests/cases/compiler/emitCapturingThisInTupleDestructuring2.ts(8,39): error TS2493: Tuple type '[number, number]' with length '2' cannot be assigned to tuple with length '3'.
+
+
+==== tests/cases/compiler/emitCapturingThisInTupleDestructuring2.ts (1 errors) ====
+    var array1: [number, number] = [1, 2];
+    
+    class B {
+        test: number;
+        test1: any;
+        test2: any;
+        method() {
+            () => [this.test, this.test1, this.test2] = array1; // even though there is a compiler error, we should still emit lexical capture for "this" 
+                                          ~~~~~~~~~~
+!!! error TS2493: Tuple type '[number, number]' with length '2' cannot be assigned to tuple with length '3'.
+        }
+    }
\ No newline at end of file
diff --git a/tests/baselines/reference/emitCapturingThisInTupleDestructuring2.js b/tests/baselines/reference/emitCapturingThisInTupleDestructuring2.js
new file mode 100644
index 00000000000..f999cfe70f0
--- /dev/null
+++ b/tests/baselines/reference/emitCapturingThisInTupleDestructuring2.js
@@ -0,0 +1,23 @@
+//// [emitCapturingThisInTupleDestructuring2.ts]
+var array1: [number, number] = [1, 2];
+
+class B {
+    test: number;
+    test1: any;
+    test2: any;
+    method() {
+        () => [this.test, this.test1, this.test2] = array1; // even though there is a compiler error, we should still emit lexical capture for "this" 
+    }
+}
+
+//// [emitCapturingThisInTupleDestructuring2.js]
+var array1 = [1, 2];
+var B = (function () {
+    function B() {
+    }
+    B.prototype.method = function () {
+        var _this = this;
+        (function () { return (_this.test = array1[0], _this.test1 = array1[1], _this.test2 = array1[2], array1); }); // even though there is a compiler error, we should still emit lexical capture for "this" 
+    };
+    return B;
+}());
diff --git a/tests/cases/compiler/emitCapturingThisInTupleDestructuring1.ts b/tests/cases/compiler/emitCapturingThisInTupleDestructuring1.ts
new file mode 100644
index 00000000000..e369cd9fb50
--- /dev/null
+++ b/tests/cases/compiler/emitCapturingThisInTupleDestructuring1.ts
@@ -0,0 +1,4 @@
+declare function wrapper(x: any);
+wrapper((array: [any]) => {
+    [this.test, this.test1, this.test2] = array;  // even though there is a compiler error, we should still emit lexical capture for "this"
+});
\ No newline at end of file
diff --git a/tests/cases/compiler/emitCapturingThisInTupleDestructuring2.ts b/tests/cases/compiler/emitCapturingThisInTupleDestructuring2.ts
new file mode 100644
index 00000000000..2bb931c4f4f
--- /dev/null
+++ b/tests/cases/compiler/emitCapturingThisInTupleDestructuring2.ts
@@ -0,0 +1,10 @@
+var array1: [number, number] = [1, 2];
+
+class B {
+    test: number;
+    test1: any;
+    test2: any;
+    method() {
+        () => [this.test, this.test1, this.test2] = array1; // even though there is a compiler error, we should still emit lexical capture for "this" 
+    }
+}
\ No newline at end of file

From f16d599f79457fee725b942d1e0ca13176950d05 Mon Sep 17 00:00:00 2001
From: Kanchalai Tanglertsampan <yuisu@microsoft.com>
Date: Tue, 9 Aug 2016 15:54:44 -0700
Subject: [PATCH 3/9] Issues an error when there are more than one export
 default

---
 src/compiler/binder.ts | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/src/compiler/binder.ts b/src/compiler/binder.ts
index 8d8666a67ab..1eedc4535dc 100644
--- a/src/compiler/binder.ts
+++ b/src/compiler/binder.ts
@@ -337,8 +337,18 @@ namespace ts {
                         ? Diagnostics.Cannot_redeclare_block_scoped_variable_0
                         : Diagnostics.Duplicate_identifier_0;
 
+                    // If the current node has NodeFlags.Default (e.g. if the node is class declaration or function declaration)
+                    // and there is already another default export (i.e. symbol.declarations is not empty), we need to report such error
+                    if (isDefaultExport && symbol.declarations) {
+                        message = Diagnostics.A_module_cannot_have_multiple_default_exports;
+                    }
+
                     forEach(symbol.declarations, declaration => {
-                        if (declaration.flags & NodeFlags.Default) {
+                        // Error on multiple export default in the following case:
+                        // 1. multiple export default of class declaration or function declaration by checking NodeFlags.Default
+                        // 2. multiple export default of export assignment. This one doesn't have NodeFlags.Default on (as export default doesn't considered as modifiers)
+                        if ((declaration.flags & NodeFlags.Default) ||
+                            (declaration.kind === SyntaxKind.ExportAssignment && !(<ExportAssignment>node).isExportEquals)) {
                             message = Diagnostics.A_module_cannot_have_multiple_default_exports;
                         }
                     });
@@ -1898,7 +1908,9 @@ namespace ts {
             }
             else {
                 // An export default clause with an expression exports a value
-                declareSymbol(container.symbol.exports, container.symbol, node, SymbolFlags.Property, SymbolFlags.PropertyExcludes | SymbolFlags.AliasExcludes);
+                // We want to exclude both class and function here,  this is necessary to issue an error when there are both
+                // default export-assignment and default export function and class declaration.
+                declareSymbol(container.symbol.exports, container.symbol, node, SymbolFlags.Property, SymbolFlags.Class | SymbolFlags.Function | SymbolFlags.Property);
             }
         }
 

From 7c3f27434c13264582e71d7b3580083a847a0fcf Mon Sep 17 00:00:00 2001
From: Kanchalai Tanglertsampan <yuisu@microsoft.com>
Date: Tue, 9 Aug 2016 15:55:26 -0700
Subject: [PATCH 4/9] Add tests and baselines

---
 .../multipleExportDefault1.errors.txt         | 19 ++++++++++++++++
 .../reference/multipleExportDefault1.js       | 20 +++++++++++++++++
 .../multipleExportDefault2.errors.txt         | 18 +++++++++++++++
 .../reference/multipleExportDefault2.js       | 18 +++++++++++++++
 .../multipleExportDefault3.errors.txt         | 18 +++++++++++++++
 .../reference/multipleExportDefault3.js       | 22 +++++++++++++++++++
 .../multipleExportDefault4.errors.txt         | 16 ++++++++++++++
 .../reference/multipleExportDefault4.js       | 20 +++++++++++++++++
 .../multipleExportDefault5.errors.txt         | 11 ++++++++++
 .../reference/multipleExportDefault5.js       | 16 ++++++++++++++
 .../multipleExportDefault6.errors.txt         | 20 +++++++++++++++++
 .../reference/multipleExportDefault6.js       | 19 ++++++++++++++++
 .../externalModules/multipleExportDefault1.ts |  7 ++++++
 .../externalModules/multipleExportDefault2.ts |  6 +++++
 .../externalModules/multipleExportDefault3.ts |  6 +++++
 .../externalModules/multipleExportDefault4.ts |  5 +++++
 .../externalModules/multipleExportDefault5.ts |  2 ++
 .../externalModules/multipleExportDefault6.ts |  7 ++++++
 18 files changed, 250 insertions(+)
 create mode 100644 tests/baselines/reference/multipleExportDefault1.errors.txt
 create mode 100644 tests/baselines/reference/multipleExportDefault1.js
 create mode 100644 tests/baselines/reference/multipleExportDefault2.errors.txt
 create mode 100644 tests/baselines/reference/multipleExportDefault2.js
 create mode 100644 tests/baselines/reference/multipleExportDefault3.errors.txt
 create mode 100644 tests/baselines/reference/multipleExportDefault3.js
 create mode 100644 tests/baselines/reference/multipleExportDefault4.errors.txt
 create mode 100644 tests/baselines/reference/multipleExportDefault4.js
 create mode 100644 tests/baselines/reference/multipleExportDefault5.errors.txt
 create mode 100644 tests/baselines/reference/multipleExportDefault5.js
 create mode 100644 tests/baselines/reference/multipleExportDefault6.errors.txt
 create mode 100644 tests/baselines/reference/multipleExportDefault6.js
 create mode 100644 tests/cases/conformance/externalModules/multipleExportDefault1.ts
 create mode 100644 tests/cases/conformance/externalModules/multipleExportDefault2.ts
 create mode 100644 tests/cases/conformance/externalModules/multipleExportDefault3.ts
 create mode 100644 tests/cases/conformance/externalModules/multipleExportDefault4.ts
 create mode 100644 tests/cases/conformance/externalModules/multipleExportDefault5.ts
 create mode 100644 tests/cases/conformance/externalModules/multipleExportDefault6.ts

diff --git a/tests/baselines/reference/multipleExportDefault1.errors.txt b/tests/baselines/reference/multipleExportDefault1.errors.txt
new file mode 100644
index 00000000000..3da6afc41e0
--- /dev/null
+++ b/tests/baselines/reference/multipleExportDefault1.errors.txt
@@ -0,0 +1,19 @@
+tests/cases/conformance/externalModules/multipleExportDefault1.ts(1,25): error TS2528: A module cannot have multiple default exports.
+tests/cases/conformance/externalModules/multipleExportDefault1.ts(5,1): error TS2528: A module cannot have multiple default exports.
+
+
+==== tests/cases/conformance/externalModules/multipleExportDefault1.ts (2 errors) ====
+    export default function Foo (){
+                            ~~~
+!!! error TS2528: A module cannot have multiple default exports.
+        
+    }
+    
+    export default {
+    ~~~~~~~~~~~~~~~~
+        uhoh: "another default",
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+    };
+    ~~
+!!! error TS2528: A module cannot have multiple default exports.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/multipleExportDefault1.js b/tests/baselines/reference/multipleExportDefault1.js
new file mode 100644
index 00000000000..bec4fb48969
--- /dev/null
+++ b/tests/baselines/reference/multipleExportDefault1.js
@@ -0,0 +1,20 @@
+//// [multipleExportDefault1.ts]
+export default function Foo (){
+    
+}
+
+export default {
+    uhoh: "another default",
+};
+
+
+//// [multipleExportDefault1.js]
+"use strict";
+function Foo() {
+}
+exports.__esModule = true;
+exports["default"] = Foo;
+exports.__esModule = true;
+exports["default"] = {
+    uhoh: "another default"
+};
diff --git a/tests/baselines/reference/multipleExportDefault2.errors.txt b/tests/baselines/reference/multipleExportDefault2.errors.txt
new file mode 100644
index 00000000000..0543e25a163
--- /dev/null
+++ b/tests/baselines/reference/multipleExportDefault2.errors.txt
@@ -0,0 +1,18 @@
+tests/cases/conformance/externalModules/multipleExportDefault2.ts(1,1): error TS2528: A module cannot have multiple default exports.
+tests/cases/conformance/externalModules/multipleExportDefault2.ts(5,25): error TS2528: A module cannot have multiple default exports.
+
+
+==== tests/cases/conformance/externalModules/multipleExportDefault2.ts (2 errors) ====
+    export default {
+    ~~~~~~~~~~~~~~~~
+        uhoh: "another default",
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+    };
+    ~~
+!!! error TS2528: A module cannot have multiple default exports.
+    
+    export default function Foo() { }
+                            ~~~
+!!! error TS2528: A module cannot have multiple default exports.
+    
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/multipleExportDefault2.js b/tests/baselines/reference/multipleExportDefault2.js
new file mode 100644
index 00000000000..dc82500a1d9
--- /dev/null
+++ b/tests/baselines/reference/multipleExportDefault2.js
@@ -0,0 +1,18 @@
+//// [multipleExportDefault2.ts]
+export default {
+    uhoh: "another default",
+};
+
+export default function Foo() { }
+
+
+
+//// [multipleExportDefault2.js]
+"use strict";
+exports.__esModule = true;
+exports["default"] = {
+    uhoh: "another default"
+};
+function Foo() { }
+exports.__esModule = true;
+exports["default"] = Foo;
diff --git a/tests/baselines/reference/multipleExportDefault3.errors.txt b/tests/baselines/reference/multipleExportDefault3.errors.txt
new file mode 100644
index 00000000000..f1e55da9112
--- /dev/null
+++ b/tests/baselines/reference/multipleExportDefault3.errors.txt
@@ -0,0 +1,18 @@
+tests/cases/conformance/externalModules/multipleExportDefault3.ts(1,1): error TS2528: A module cannot have multiple default exports.
+tests/cases/conformance/externalModules/multipleExportDefault3.ts(5,22): error TS2528: A module cannot have multiple default exports.
+
+
+==== tests/cases/conformance/externalModules/multipleExportDefault3.ts (2 errors) ====
+    export default {
+    ~~~~~~~~~~~~~~~~
+        uhoh: "another default",
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+    };
+    ~~
+!!! error TS2528: A module cannot have multiple default exports.
+    
+    export default class C { }
+                         ~
+!!! error TS2528: A module cannot have multiple default exports.
+    
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/multipleExportDefault3.js b/tests/baselines/reference/multipleExportDefault3.js
new file mode 100644
index 00000000000..5d7ad48e0ca
--- /dev/null
+++ b/tests/baselines/reference/multipleExportDefault3.js
@@ -0,0 +1,22 @@
+//// [multipleExportDefault3.ts]
+export default {
+    uhoh: "another default",
+};
+
+export default class C { }
+
+
+
+//// [multipleExportDefault3.js]
+"use strict";
+exports.__esModule = true;
+exports["default"] = {
+    uhoh: "another default"
+};
+var C = (function () {
+    function C() {
+    }
+    return C;
+}());
+exports.__esModule = true;
+exports["default"] = C;
diff --git a/tests/baselines/reference/multipleExportDefault4.errors.txt b/tests/baselines/reference/multipleExportDefault4.errors.txt
new file mode 100644
index 00000000000..bba15527d00
--- /dev/null
+++ b/tests/baselines/reference/multipleExportDefault4.errors.txt
@@ -0,0 +1,16 @@
+tests/cases/conformance/externalModules/multipleExportDefault4.ts(1,22): error TS2528: A module cannot have multiple default exports.
+tests/cases/conformance/externalModules/multipleExportDefault4.ts(3,1): error TS2528: A module cannot have multiple default exports.
+
+
+==== tests/cases/conformance/externalModules/multipleExportDefault4.ts (2 errors) ====
+    export default class C { }
+                         ~
+!!! error TS2528: A module cannot have multiple default exports.
+    
+    export default {
+    ~~~~~~~~~~~~~~~~
+        uhoh: "another default",
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+    };
+    ~~
+!!! error TS2528: A module cannot have multiple default exports.
\ No newline at end of file
diff --git a/tests/baselines/reference/multipleExportDefault4.js b/tests/baselines/reference/multipleExportDefault4.js
new file mode 100644
index 00000000000..1199fa91c9c
--- /dev/null
+++ b/tests/baselines/reference/multipleExportDefault4.js
@@ -0,0 +1,20 @@
+//// [multipleExportDefault4.ts]
+export default class C { }
+
+export default {
+    uhoh: "another default",
+};
+
+//// [multipleExportDefault4.js]
+"use strict";
+var C = (function () {
+    function C() {
+    }
+    return C;
+}());
+exports.__esModule = true;
+exports["default"] = C;
+exports.__esModule = true;
+exports["default"] = {
+    uhoh: "another default"
+};
diff --git a/tests/baselines/reference/multipleExportDefault5.errors.txt b/tests/baselines/reference/multipleExportDefault5.errors.txt
new file mode 100644
index 00000000000..30c87339ff2
--- /dev/null
+++ b/tests/baselines/reference/multipleExportDefault5.errors.txt
@@ -0,0 +1,11 @@
+tests/cases/conformance/externalModules/multipleExportDefault5.ts(1,25): error TS2528: A module cannot have multiple default exports.
+tests/cases/conformance/externalModules/multipleExportDefault5.ts(2,22): error TS2528: A module cannot have multiple default exports.
+
+
+==== tests/cases/conformance/externalModules/multipleExportDefault5.ts (2 errors) ====
+    export default function bar() { }
+                            ~~~
+!!! error TS2528: A module cannot have multiple default exports.
+    export default class C {}
+                         ~
+!!! error TS2528: A module cannot have multiple default exports.
\ No newline at end of file
diff --git a/tests/baselines/reference/multipleExportDefault5.js b/tests/baselines/reference/multipleExportDefault5.js
new file mode 100644
index 00000000000..7ae33aee9f4
--- /dev/null
+++ b/tests/baselines/reference/multipleExportDefault5.js
@@ -0,0 +1,16 @@
+//// [multipleExportDefault5.ts]
+export default function bar() { }
+export default class C {}
+
+//// [multipleExportDefault5.js]
+"use strict";
+function bar() { }
+exports.__esModule = true;
+exports["default"] = bar;
+var C = (function () {
+    function C() {
+    }
+    return C;
+}());
+exports.__esModule = true;
+exports["default"] = C;
diff --git a/tests/baselines/reference/multipleExportDefault6.errors.txt b/tests/baselines/reference/multipleExportDefault6.errors.txt
new file mode 100644
index 00000000000..a8bf80e8df0
--- /dev/null
+++ b/tests/baselines/reference/multipleExportDefault6.errors.txt
@@ -0,0 +1,20 @@
+tests/cases/conformance/externalModules/multipleExportDefault6.ts(1,1): error TS2528: A module cannot have multiple default exports.
+tests/cases/conformance/externalModules/multipleExportDefault6.ts(5,1): error TS2528: A module cannot have multiple default exports.
+
+
+==== tests/cases/conformance/externalModules/multipleExportDefault6.ts (2 errors) ====
+    export default {
+    ~~~~~~~~~~~~~~~~
+        lol: 1
+    ~~~~~~~~~~
+    }
+    ~
+!!! error TS2528: A module cannot have multiple default exports.
+    
+    export default {
+    ~~~~~~~~~~~~~~~~
+        lol: 2
+    ~~~~~~~~~~
+    }
+    ~
+!!! error TS2528: A module cannot have multiple default exports.
\ No newline at end of file
diff --git a/tests/baselines/reference/multipleExportDefault6.js b/tests/baselines/reference/multipleExportDefault6.js
new file mode 100644
index 00000000000..a8b93459e4e
--- /dev/null
+++ b/tests/baselines/reference/multipleExportDefault6.js
@@ -0,0 +1,19 @@
+//// [multipleExportDefault6.ts]
+export default {
+    lol: 1
+}
+
+export default {
+    lol: 2
+}
+
+//// [multipleExportDefault6.js]
+"use strict";
+exports.__esModule = true;
+exports["default"] = {
+    lol: 1
+};
+exports.__esModule = true;
+exports["default"] = {
+    lol: 2
+};
diff --git a/tests/cases/conformance/externalModules/multipleExportDefault1.ts b/tests/cases/conformance/externalModules/multipleExportDefault1.ts
new file mode 100644
index 00000000000..623cc2acc20
--- /dev/null
+++ b/tests/cases/conformance/externalModules/multipleExportDefault1.ts
@@ -0,0 +1,7 @@
+export default function Foo (){
+    
+}
+
+export default {
+    uhoh: "another default",
+};
diff --git a/tests/cases/conformance/externalModules/multipleExportDefault2.ts b/tests/cases/conformance/externalModules/multipleExportDefault2.ts
new file mode 100644
index 00000000000..0e14b570aa1
--- /dev/null
+++ b/tests/cases/conformance/externalModules/multipleExportDefault2.ts
@@ -0,0 +1,6 @@
+export default {
+    uhoh: "another default",
+};
+
+export default function Foo() { }
+
diff --git a/tests/cases/conformance/externalModules/multipleExportDefault3.ts b/tests/cases/conformance/externalModules/multipleExportDefault3.ts
new file mode 100644
index 00000000000..3b5460e8141
--- /dev/null
+++ b/tests/cases/conformance/externalModules/multipleExportDefault3.ts
@@ -0,0 +1,6 @@
+export default {
+    uhoh: "another default",
+};
+
+export default class C { }
+
diff --git a/tests/cases/conformance/externalModules/multipleExportDefault4.ts b/tests/cases/conformance/externalModules/multipleExportDefault4.ts
new file mode 100644
index 00000000000..6181c360798
--- /dev/null
+++ b/tests/cases/conformance/externalModules/multipleExportDefault4.ts
@@ -0,0 +1,5 @@
+export default class C { }
+
+export default {
+    uhoh: "another default",
+};
\ No newline at end of file
diff --git a/tests/cases/conformance/externalModules/multipleExportDefault5.ts b/tests/cases/conformance/externalModules/multipleExportDefault5.ts
new file mode 100644
index 00000000000..d2b67fce46f
--- /dev/null
+++ b/tests/cases/conformance/externalModules/multipleExportDefault5.ts
@@ -0,0 +1,2 @@
+export default function bar() { }
+export default class C {}
\ No newline at end of file
diff --git a/tests/cases/conformance/externalModules/multipleExportDefault6.ts b/tests/cases/conformance/externalModules/multipleExportDefault6.ts
new file mode 100644
index 00000000000..889ae64376b
--- /dev/null
+++ b/tests/cases/conformance/externalModules/multipleExportDefault6.ts
@@ -0,0 +1,7 @@
+export default {
+    lol: 1
+}
+
+export default {
+    lol: 2
+}
\ No newline at end of file

From 042da569f71b40b0723b92259dc8a197c64580a5 Mon Sep 17 00:00:00 2001
From: Kanchalai Tanglertsampan <yuisu@microsoft.com>
Date: Thu, 11 Aug 2016 10:04:22 -0700
Subject: [PATCH 5/9] Address PR: add comment

---
 src/compiler/binder.ts | 27 +++++++++++++++------------
 1 file changed, 15 insertions(+), 12 deletions(-)

diff --git a/src/compiler/binder.ts b/src/compiler/binder.ts
index 1eedc4535dc..2547dd2cd5a 100644
--- a/src/compiler/binder.ts
+++ b/src/compiler/binder.ts
@@ -337,21 +337,24 @@ namespace ts {
                         ? Diagnostics.Cannot_redeclare_block_scoped_variable_0
                         : Diagnostics.Duplicate_identifier_0;
 
-                    // If the current node has NodeFlags.Default (e.g. if the node is class declaration or function declaration)
-                    // and there is already another default export (i.e. symbol.declarations is not empty), we need to report such error
+                    // If the current node is a default export of some sort, then check if
+                    // there are any other default exports that we need to error on.
+                    // We'll know whether we have other default exports depending on if `symbol` already has a declaration list set.
                     if (isDefaultExport && symbol.declarations) {
                         message = Diagnostics.A_module_cannot_have_multiple_default_exports;
                     }
-
-                    forEach(symbol.declarations, declaration => {
-                        // Error on multiple export default in the following case:
-                        // 1. multiple export default of class declaration or function declaration by checking NodeFlags.Default
-                        // 2. multiple export default of export assignment. This one doesn't have NodeFlags.Default on (as export default doesn't considered as modifiers)
-                        if ((declaration.flags & NodeFlags.Default) ||
-                            (declaration.kind === SyntaxKind.ExportAssignment && !(<ExportAssignment>node).isExportEquals)) {
-                            message = Diagnostics.A_module_cannot_have_multiple_default_exports;
-                        }
-                    });
+                    else {
+                        // This is to properly report an error in the case "export default { }" is after export default of class declaration or function declaration.
+                        forEach(symbol.declarations, declaration => {
+                            // Error on multiple export default in the following case:
+                            // 1. multiple export default of class declaration or function declaration by checking NodeFlags.Default
+                            // 2. multiple export default of export assignment. This one doesn't have NodeFlags.Default on (as export default doesn't considered as modifiers)
+                            if ((declaration.flags & NodeFlags.Default) ||
+                                (declaration.kind === SyntaxKind.ExportAssignment && !(<ExportAssignment>node).isExportEquals)) {
+                                message = Diagnostics.A_module_cannot_have_multiple_default_exports;
+                            }
+                        });
+                    }
 
                     forEach(symbol.declarations, declaration => {
                         file.bindDiagnostics.push(createDiagnosticForNode(declaration.name || declaration, message, getDisplayName(declaration)));

From 821348b75d60f095f4e88a036fd4928a51527b99 Mon Sep 17 00:00:00 2001
From: Kanchalai Tanglertsampan <yuisu@microsoft.com>
Date: Thu, 11 Aug 2016 10:48:43 -0700
Subject: [PATCH 6/9] Update baseline

---
 ...sFileCompilationBindMultipleDefaultExports.errors.txt | 8 +++++++-
 .../reference/multipleDefaultExports01.errors.txt        | 9 +++------
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/tests/baselines/reference/jsFileCompilationBindMultipleDefaultExports.errors.txt b/tests/baselines/reference/jsFileCompilationBindMultipleDefaultExports.errors.txt
index 4c1d237aa47..05fecf03d30 100644
--- a/tests/baselines/reference/jsFileCompilationBindMultipleDefaultExports.errors.txt
+++ b/tests/baselines/reference/jsFileCompilationBindMultipleDefaultExports.errors.txt
@@ -1,9 +1,15 @@
+tests/cases/compiler/a.js(1,22): error TS2528: A module cannot have multiple default exports.
+tests/cases/compiler/a.js(3,1): error TS2528: A module cannot have multiple default exports.
 tests/cases/compiler/a.js(3,16): error TS1109: Expression expected.
 
 
-==== tests/cases/compiler/a.js (1 errors) ====
+==== tests/cases/compiler/a.js (3 errors) ====
     export default class a {
+                         ~
+!!! error TS2528: A module cannot have multiple default exports.
     }
     export default var a = 10;
+    ~~~~~~~~~~~~~~
+!!! error TS2528: A module cannot have multiple default exports.
                    ~~~
 !!! error TS1109: Expression expected.
\ No newline at end of file
diff --git a/tests/baselines/reference/multipleDefaultExports01.errors.txt b/tests/baselines/reference/multipleDefaultExports01.errors.txt
index b3e7d757289..16aa3b2f7b1 100644
--- a/tests/baselines/reference/multipleDefaultExports01.errors.txt
+++ b/tests/baselines/reference/multipleDefaultExports01.errors.txt
@@ -1,16 +1,13 @@
-tests/cases/conformance/es6/modules/m1.ts(2,22): error TS2323: Cannot redeclare exported variable 'default'.
 tests/cases/conformance/es6/modules/m1.ts(2,22): error TS2528: A module cannot have multiple default exports.
 tests/cases/conformance/es6/modules/m1.ts(6,25): error TS2528: A module cannot have multiple default exports.
-tests/cases/conformance/es6/modules/m1.ts(11,1): error TS2323: Cannot redeclare exported variable 'default'.
+tests/cases/conformance/es6/modules/m1.ts(11,1): error TS2528: A module cannot have multiple default exports.
 tests/cases/conformance/es6/modules/m2.ts(3,1): error TS2348: Value of type 'typeof foo' is not callable. Did you mean to include 'new'?
 
 
-==== tests/cases/conformance/es6/modules/m1.ts (4 errors) ====
+==== tests/cases/conformance/es6/modules/m1.ts (3 errors) ====
     
     export default class foo {
                          ~~~
-!!! error TS2323: Cannot redeclare exported variable 'default'.
-                         ~~~
 !!! error TS2528: A module cannot have multiple default exports.
     
     }
@@ -24,7 +21,7 @@ tests/cases/conformance/es6/modules/m2.ts(3,1): error TS2348: Value of type 'typ
     var x = 10;
     export default x;
     ~~~~~~~~~~~~~~~~~
-!!! error TS2323: Cannot redeclare exported variable 'default'.
+!!! error TS2528: A module cannot have multiple default exports.
     
 ==== tests/cases/conformance/es6/modules/m2.ts (1 errors) ====
     import Entity from "./m1"

From 3479f4bcbe233adcd0dd500686de3bf18b8efd57 Mon Sep 17 00:00:00 2001
From: Kanchalai Tanglertsampan <yuisu@microsoft.com>
Date: Thu, 11 Aug 2016 10:49:36 -0700
Subject: [PATCH 7/9] fix linting

---
 src/compiler/binder.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/compiler/binder.ts b/src/compiler/binder.ts
index 573bd0b7e35..c3dab267d02 100644
--- a/src/compiler/binder.ts
+++ b/src/compiler/binder.ts
@@ -1913,7 +1913,7 @@ namespace ts {
                     ? SymbolFlags.Alias
                     // An export default clause with any other expression exports a value
                     : SymbolFlags.Property;
-                declareSymbol(container.symbol.exports, container.symbol, node, flags, SymbolFlags.Property | SymbolFlags.AliasExcludes | SymbolFlags.Class | SymbolFlags.Function); //SymbolFlags.Class | SymbolFlags.Function | SymbolFlags.Property);
+                declareSymbol(container.symbol.exports, container.symbol, node, flags, SymbolFlags.Property | SymbolFlags.AliasExcludes | SymbolFlags.Class | SymbolFlags.Function);
             }
         }
 

From 7b525ea99fb6befa87032741de972dfc0a8f650e Mon Sep 17 00:00:00 2001
From: Kanchalai Tanglertsampan <yuisu@microsoft.com>
Date: Wed, 17 Aug 2016 16:06:13 -0700
Subject: [PATCH 8/9] Use for..of instead

---
 src/compiler/binder.ts | 35 +++++++++++++++++++----------------
 1 file changed, 19 insertions(+), 16 deletions(-)

diff --git a/src/compiler/binder.ts b/src/compiler/binder.ts
index 45dbab15732..5e065a00d2f 100644
--- a/src/compiler/binder.ts
+++ b/src/compiler/binder.ts
@@ -349,23 +349,26 @@ namespace ts {
                             ? Diagnostics.Cannot_redeclare_block_scoped_variable_0
                             : Diagnostics.Duplicate_identifier_0;
 
-                        // If the current node is a default export of some sort, then check if
-                        // there are any other default exports that we need to error on.
-                        // We'll know whether we have other default exports depending on if `symbol` already has a declaration list set.
-                        if (isDefaultExport && symbol.declarations) {
-                            message = Diagnostics.A_module_cannot_have_multiple_default_exports;
-                        }
-                        else {
-                            // This is to properly report an error in the case "export default { }" is after export default of class declaration or function declaration.
-                            forEach(symbol.declarations, declaration => {
-                                // Error on multiple export default in the following case:
-                                // 1. multiple export default of class declaration or function declaration by checking NodeFlags.Default
-                                // 2. multiple export default of export assignment. This one doesn't have NodeFlags.Default on (as export default doesn't considered as modifiers)
-                                if ((declaration.flags & NodeFlags.Default) ||
-                                    (declaration.kind === SyntaxKind.ExportAssignment && !(<ExportAssignment>node).isExportEquals)) {
-                                    message = Diagnostics.A_module_cannot_have_multiple_default_exports;
+                        if (symbol.declarations && symbol.declarations.length) {
+                            // If the current node is a default export of some sort, then check if
+                            // there are any other default exports that we need to error on.
+                            // We'll know whether we have other default exports depending on if `symbol` already has a declaration list set.
+                            if (isDefaultExport) {
+                                message = Diagnostics.A_module_cannot_have_multiple_default_exports;
+                            }
+                            else {
+                                // This is to properly report an error in the case "export default { }" is after export default of class declaration or function declaration.
+                                for (const declaration of symbol.declarations) {
+                                    // Error on multiple export default in the following case:
+                                    // 1. multiple export default of class declaration or function declaration by checking NodeFlags.Default
+                                    // 2. multiple export default of export assignment. This one doesn't have NodeFlags.Default on (as export default doesn't considered as modifiers)
+                                    if ((declaration.flags & NodeFlags.Default) ||
+                                        (declaration.kind === SyntaxKind.ExportAssignment && !(<ExportAssignment>node).isExportEquals)) {
+                                        message = Diagnostics.A_module_cannot_have_multiple_default_exports;
+                                        break;
+                                    }
                                 }
-                            });
+                            }
                         }
 
                         forEach(symbol.declarations, declaration => {

From a5a71693b73031130fb74c9322c23ee79db2aef2 Mon Sep 17 00:00:00 2001
From: Kanchalai Tanglertsampan <yuisu@microsoft.com>
Date: Thu, 29 Sep 2016 18:02:59 -0700
Subject: [PATCH 9/9] Address PR

---
 src/compiler/binder.ts | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/src/compiler/binder.ts b/src/compiler/binder.ts
index 5e065a00d2f..65034476aa1 100644
--- a/src/compiler/binder.ts
+++ b/src/compiler/binder.ts
@@ -358,16 +358,13 @@ namespace ts {
                             }
                             else {
                                 // This is to properly report an error in the case "export default { }" is after export default of class declaration or function declaration.
-                                for (const declaration of symbol.declarations) {
-                                    // Error on multiple export default in the following case:
-                                    // 1. multiple export default of class declaration or function declaration by checking NodeFlags.Default
-                                    // 2. multiple export default of export assignment. This one doesn't have NodeFlags.Default on (as export default doesn't considered as modifiers)
-                                    if ((declaration.flags & NodeFlags.Default) ||
-                                        (declaration.kind === SyntaxKind.ExportAssignment && !(<ExportAssignment>node).isExportEquals)) {
+                                // Error on multiple export default in the following case:
+                                // 1. multiple export default of class declaration or function declaration by checking NodeFlags.Default
+                                // 2. multiple export default of export assignment. This one doesn't have NodeFlags.Default on (as export default doesn't considered as modifiers)
+                                if (symbol.declarations && symbol.declarations.length &&
+                                    (isDefaultExport || (node.kind === SyntaxKind.ExportAssignment &&  !(<ExportAssignment>node).isExportEquals))) {
                                         message = Diagnostics.A_module_cannot_have_multiple_default_exports;
-                                        break;
-                                    }
-                                }
+                                 }
                             }
                         }