From 139f10fb441ea2e531200116f0b43c93a1a1401f Mon Sep 17 00:00:00 2001
From: Wesley Wigham <t-weswig@microsoft.com>
Date: Thu, 10 Dec 2015 14:08:50 -0800
Subject: [PATCH 1/2] test for and fix #6043

---
 src/compiler/checker.ts                           |  3 ++-
 tests/baselines/reference/typeAliasExport.js      |  8 ++++++++
 tests/baselines/reference/typeAliasExport.symbols | 10 ++++++++++
 tests/baselines/reference/typeAliasExport.types   | 10 ++++++++++
 tests/cases/compiler/typeAliasExport.ts           |  5 +++++
 5 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100644 tests/baselines/reference/typeAliasExport.js
 create mode 100644 tests/baselines/reference/typeAliasExport.symbols
 create mode 100644 tests/baselines/reference/typeAliasExport.types
 create mode 100644 tests/cases/compiler/typeAliasExport.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 0ee73756e57..1073e8eda9b 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -14310,8 +14310,9 @@ namespace ts {
                         continue;
                     }
                     const { declarations, flags } = exports[id];
+                    let declarationLength = declarations.length;
                     // ECMA262: 15.2.1.1 It is a Syntax Error if the ExportedNames of ModuleItemList contains any duplicate entries. (TS Exceptions: namespaces, function overloads, enums, and interfaces)
-                    if (!(flags & (SymbolFlags.Namespace | SymbolFlags.Interface | SymbolFlags.Enum)) && declarations.length > 1) {
+                    if (!(flags & (SymbolFlags.Namespace | SymbolFlags.Interface | SymbolFlags.Enum)) && (flags & SymbolFlags.TypeAlias ? declarationLength-- : true) && declarationLength > 1) {
                         const exportedDeclarations: Declaration[] = filter(declarations, isNotOverload);
                         if (exportedDeclarations.length > 1) {
                             for (const declaration of exportedDeclarations) {
diff --git a/tests/baselines/reference/typeAliasExport.js b/tests/baselines/reference/typeAliasExport.js
new file mode 100644
index 00000000000..fa864f571ea
--- /dev/null
+++ b/tests/baselines/reference/typeAliasExport.js
@@ -0,0 +1,8 @@
+//// [typeAliasExport.ts]
+declare module "a" {
+  export default 0
+  export var a;
+  export type a = typeof a;
+}
+
+//// [typeAliasExport.js]
diff --git a/tests/baselines/reference/typeAliasExport.symbols b/tests/baselines/reference/typeAliasExport.symbols
new file mode 100644
index 00000000000..1f580b03011
--- /dev/null
+++ b/tests/baselines/reference/typeAliasExport.symbols
@@ -0,0 +1,10 @@
+=== tests/cases/compiler/typeAliasExport.ts ===
+declare module "a" {
+  export default 0
+  export var a;
+>a : Symbol(a, Decl(typeAliasExport.ts, 2, 12), Decl(typeAliasExport.ts, 2, 15))
+
+  export type a = typeof a;
+>a : Symbol(a, Decl(typeAliasExport.ts, 2, 12), Decl(typeAliasExport.ts, 2, 15))
+>a : Symbol(a, Decl(typeAliasExport.ts, 2, 12), Decl(typeAliasExport.ts, 2, 15))
+}
diff --git a/tests/baselines/reference/typeAliasExport.types b/tests/baselines/reference/typeAliasExport.types
new file mode 100644
index 00000000000..afa26073061
--- /dev/null
+++ b/tests/baselines/reference/typeAliasExport.types
@@ -0,0 +1,10 @@
+=== tests/cases/compiler/typeAliasExport.ts ===
+declare module "a" {
+  export default 0
+  export var a;
+>a : any
+
+  export type a = typeof a;
+>a : any
+>a : any
+}
diff --git a/tests/cases/compiler/typeAliasExport.ts b/tests/cases/compiler/typeAliasExport.ts
new file mode 100644
index 00000000000..706b731f0ab
--- /dev/null
+++ b/tests/cases/compiler/typeAliasExport.ts
@@ -0,0 +1,5 @@
+declare module "a" {
+  export default 0
+  export var a;
+  export type a = typeof a;
+}
\ No newline at end of file

From ef6c137f9e73d29833fb443a0ff604a44a6162a1 Mon Sep 17 00:00:00 2001
From: Wesley Wigham <t-weswig@microsoft.com>
Date: Thu, 10 Dec 2015 19:55:08 -0800
Subject: [PATCH 2/2] add feedback from PR

---
 src/compiler/checker.ts | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 1073e8eda9b..666d983bd52 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -14310,9 +14310,8 @@ namespace ts {
                         continue;
                     }
                     const { declarations, flags } = exports[id];
-                    let declarationLength = declarations.length;
                     // ECMA262: 15.2.1.1 It is a Syntax Error if the ExportedNames of ModuleItemList contains any duplicate entries. (TS Exceptions: namespaces, function overloads, enums, and interfaces)
-                    if (!(flags & (SymbolFlags.Namespace | SymbolFlags.Interface | SymbolFlags.Enum)) && (flags & SymbolFlags.TypeAlias ? declarationLength-- : true) && declarationLength > 1) {
+                    if (!(flags & (SymbolFlags.Namespace | SymbolFlags.Interface | SymbolFlags.Enum)) && (flags & SymbolFlags.TypeAlias ? declarations.length - 1 : declarations.length) > 1) {
                         const exportedDeclarations: Declaration[] = filter(declarations, isNotOverload);
                         if (exportedDeclarations.length > 1) {
                             for (const declaration of exportedDeclarations) {