From 1829b71255e3e08530c654ac213da3f4ae49cf07 Mon Sep 17 00:00:00 2001
From: Jon Hanna <jon@hackcraft.net>
Date: Wed, 4 Jan 2017 14:51:49 +0000
Subject: [PATCH] Optimise LinqBridge.Enumerable.Cast for direct cast
 available.

(This changes the behaviour to return same type, but framework Linq has
the same optimisation).
---
 Src/Newtonsoft.Json/Utilities/LinqBridge.cs | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/Src/Newtonsoft.Json/Utilities/LinqBridge.cs b/Src/Newtonsoft.Json/Utilities/LinqBridge.cs
index f24636f8..b5bdc1ba 100644
--- a/Src/Newtonsoft.Json/Utilities/LinqBridge.cs
+++ b/Src/Newtonsoft.Json/Utilities/LinqBridge.cs
@@ -72,7 +72,14 @@ namespace Newtonsoft.Json.Utilities.LinqBridge
     {
       CheckNotNull(source, "source");
 
-      return CastYield<TResult>(source);
+        var servesItself = source as IEnumerable<TResult>;
+        if (servesItself != null
+            && (!(servesItself is TResult[]) || servesItself.GetType().GetElementType() == typeof(TResult)))
+        {
+            return servesItself;
+        }
+
+        return CastYield<TResult>(source);
     }
 
     private static IEnumerable<TResult> CastYield<TResult>(