From 6400d53394def163795e77bf35ea0ce87d2db53d Mon Sep 17 00:00:00 2001
From: Arthur Ozga <arozga@microsoft.com>
Date: Mon, 14 Nov 2016 15:43:24 -0800
Subject: [PATCH] Fix handling of default class

---
 src/compiler/utilities.ts                                | 2 +-
 .../codefixes/fixClassIncorrectlyImplementsInterface.ts  | 5 +++--
 .../cases/fourslash/codeFixUnImplementedDefaultClass.ts  | 9 +++++++++
 3 files changed, 13 insertions(+), 3 deletions(-)
 create mode 100644 tests/cases/fourslash/codeFixUnImplementedDefaultClass.ts

diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index 299f91be662..eafac479807 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -1801,7 +1801,7 @@ namespace ts {
         }
     }
 
-    export function getAncestor(node: Node, kind: SyntaxKind): Node {
+    export function getAncestor(node: Node | undefined, kind: SyntaxKind): Node {
         while (node) {
             if (node.kind === kind) {
                 return node;
diff --git a/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts b/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts
index 9bcf491ac5b..f8da7ae2218 100644
--- a/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts
+++ b/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts
@@ -8,10 +8,11 @@ namespace ts.codefix {
             const token = getTokenAtPosition(sourceFile, start);
             const checker = context.program.getTypeChecker();
 
-            if (!(token.kind === SyntaxKind.Identifier && isClassLike(token.parent))) {
+            const classDecl = getAncestor(token, SyntaxKind.ClassDeclaration) as ClassDeclaration;
+            if (!(classDecl && isClassLike(classDecl))) {
                 return undefined;
             }
-            const classDecl = <ClassDeclaration>token.parent;
+
             const startPos: number = classDecl.members.pos;
 
             const implementedTypeNodes = getClassImplementsHeritageClauseElements(classDecl);
diff --git a/tests/cases/fourslash/codeFixUnImplementedDefaultClass.ts b/tests/cases/fourslash/codeFixUnImplementedDefaultClass.ts
new file mode 100644
index 00000000000..9f507c3dc60
--- /dev/null
+++ b/tests/cases/fourslash/codeFixUnImplementedDefaultClass.ts
@@ -0,0 +1,9 @@
+/// <reference path='fourslash.ts' />
+
+//// interface I { x: number; }
+////
+//// export default class implements I {[| |]}
+
+verify.rangeAfterCodeFix(`
+x: number;
+`);
\ No newline at end of file