From c700bf9e7ddae671dcba397e3e5b9a5c6308191c Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Sat, 5 Dec 2015 16:57:02 -0800
Subject: [PATCH] Fix length check in typeArgumentsRelatedTo

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

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index e0fe647f7c7..c4cda31a0ba 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -5232,8 +5232,9 @@ namespace ts {
                 if (sources.length !== targets.length && relation === identityRelation) {
                     return Ternary.False;
                 }
+                const length = sources.length <= targets.length ? sources.length : targets.length;
                 let result = Ternary.True;
-                for (let i = 0; i < targets.length; i++) {
+                for (let i = 0; i < length; i++) {
                     const related = isRelatedTo(sources[i], targets[i], reportErrors);
                     if (!related) {
                         return Ternary.False;