From fd948ac6d2a076ce65b95bb50ce2a72b2f78d8f2 Mon Sep 17 00:00:00 2001
From: Andy <anhans@microsoft.com>
Date: Wed, 15 Aug 2018 10:17:18 -0700
Subject: [PATCH] Fix invalid cast (#26462)

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

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index c3c982ecfe..3beb4ac59b 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -26696,7 +26696,7 @@ namespace ts {
                 case SyntaxKind.ParenthesizedType:
                 case SyntaxKind.OptionalType:
                 case SyntaxKind.RestType:
-                    return checkSourceElement((<ParenthesizedTypeNode | OptionalTypeNode>node).type);
+                    return checkSourceElement((<ParenthesizedTypeNode | OptionalTypeNode | RestTypeNode>node).type);
                 case SyntaxKind.ThisType:
                     return checkThisType(<ThisTypeNode>node);
                 case SyntaxKind.TypeOperator: