From 517d7d983fe04a2843fd64a57e289b1c2b013727 Mon Sep 17 00:00:00 2001
From: Vladimir Matveev <vladima@microsoft.com>
Date: Fri, 19 Feb 2016 22:05:17 -0800
Subject: [PATCH 1/2] do not make inferences with the same source\target pair
 multiple times

---
 src/compiler/checker.ts | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index dbce5f41ef4..b6e68cb1dc3 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -6524,6 +6524,7 @@ namespace ts {
             let targetStack: Type[];
             let depth = 0;
             let inferiority = 0;
+            const visited: Map<boolean> = {};
             inferFromTypes(source, target);
 
             function isInProcess(source: Type, target: Type) {
@@ -6653,6 +6654,12 @@ namespace ts {
                             return;
                         }
 
+                        const key = source.id + "," + target.id;
+                        if (hasProperty(visited, key)) {
+                            return;
+                        }
+                        visited[key] = true;
+
                         if (depth === 0) {
                             sourceStack = [];
                             targetStack = [];

From 26336cd54b5b9a17c1a719de717354e003216102 Mon Sep 17 00:00:00 2001
From: Vladimir Matveev <vladima@microsoft.com>
Date: Fri, 19 Feb 2016 22:32:05 -0800
Subject: [PATCH 2/2] fix linter issues

---
 src/server/protocol.d.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/server/protocol.d.ts b/src/server/protocol.d.ts
index 3a669753323..c50f211a21f 100644
--- a/src/server/protocol.d.ts
+++ b/src/server/protocol.d.ts
@@ -469,7 +469,7 @@ declare namespace ts.server.protocol {
         placeOpenBraceOnNewLineForControlBlocks?: boolean;
 
         /** Index operator */
-        [key: string] : string | number | boolean;
+        [key: string]: string | number | boolean;
     }
 
     /**