From be18057792ced9a9edacf65968ee975bc33344b6 Mon Sep 17 00:00:00 2001
From: Wesley Wigham <wewigham@microsoft.com>
Date: Thu, 4 Feb 2021 13:20:38 -0800
Subject: [PATCH] Add check for no match into fs watch rename event handler
 (#42651)

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

diff --git a/src/compiler/sys.ts b/src/compiler/sys.ts
index b0f21dab80c..5dc4fbe91cc 100644
--- a/src/compiler/sys.ts
+++ b/src/compiler/sys.ts
@@ -1560,7 +1560,7 @@ namespace ts {
                     return event === "rename" &&
                         (!relativeName ||
                             relativeName === lastDirectoryPart ||
-                            relativeName.lastIndexOf(lastDirectoryPartWithDirectorySeparator!) === relativeName.length - lastDirectoryPartWithDirectorySeparator!.length) &&
+                            (relativeName.lastIndexOf(lastDirectoryPartWithDirectorySeparator!) !== -1 && relativeName.lastIndexOf(lastDirectoryPartWithDirectorySeparator!) === relativeName.length - lastDirectoryPartWithDirectorySeparator!.length)) &&
                         !fileSystemEntryExists(fileOrDirectory, entryKind) ?
                         invokeCallbackAndUpdateWatcher(watchMissingFileSystemEntry) :
                         callback(event, relativeName);