Revert forced failure

Author: EmandM

com.unity.netcode.gameobjects/Runtime/Messaging/NetworkMessageManager.cs

@@ -503,9 +503,9 @@ internal void CleanupDisconnectedClients()
             m_DisconnectedClients.Clear();
         }
 
-        public static int CreateMessageAndGetVersion<T>() where T : INetworkMessage, new()
+        public static int CreateMessageAndGetVersion<T>() where T : struct, INetworkMessage
         {
-            return new T().Version;
+            return default(T).Version;
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
@@ -538,18 +538,10 @@ internal int GetMessageVersion(Type type, ulong clientId, bool forReceive = fals
 
 
 
-        public static void ReceiveMessage<T>(FastBufferReader reader, ref NetworkContext context, NetworkMessageManager manager) where T : INetworkMessage, new()
+        public static void ReceiveMessage<T>(FastBufferReader reader, ref NetworkContext context, NetworkMessageManager manager) where T : struct, INetworkMessage
         {
             var messageType = typeof(T);
-
-            // new(T) is boxed by Mono and so will make an allocation even when T is a struct. default(T) avoids the allocation.
-            var message = new T();
-            // If T is a class, default(T) will be null. Users can register classes as custom messages, so we need to ensure we create a valid instance.
-            // if (message == null)
-            // {
-            //     message = new T();
-            // }
-
+            var message = default(T);
             var messageVersion = 0;
 
             // Special cases because these are the messages that carry the version info - thus the version info isn't

com.unity.netcode.gameobjects/Runtime/Serialization/FastBufferReader.cs

@@ -493,14 +493,7 @@ public unsafe byte[] ToArray()
         /// <exception cref="NotImplementedException">Thrown if the type T does not properly implement NetworkSerialize</exception>
         public void ReadNetworkSerializable<T>(out T value) where T : INetworkSerializable, new()
         {
-            // new T() will always cause an allocation.
-            // Assign default first to see if T is a value type with a valid default
-            value = default;
-            if (value == null)
-            {
-                // The allocation is unavoidable, ensure T is created.
-                value = new T();
-            }
+            value = new T();
             var bufferSerializer = new BufferSerializer<BufferSerializerReader>(new BufferSerializerReader(this));
             value.NetworkSerialize(bufferSerializer);
         }

com.unity.netcode.gameobjects/Tests/Editor/Messaging/MessageReceivingTests.cs

@@ -17,7 +17,7 @@ private struct TestMessage : INetworkMessage, INetworkSerializeByMemcpy
             public int C;
             public static bool Deserialized;
             public static bool Handled;
-            public static List<TestMessage> DeserializedValues = new List<TestMessage>(100000);
+            public static List<TestMessage> DeserializedValues = new List<TestMessage>();
 
             public void Serialize(FastBufferWriter writer, int targetVersion)
             {

com.unity.netcode.gameobjects/Tests/Runtime/Helpers/MessageCatcher.cs

@@ -1,7 +1,6 @@
 using System;
 using System.Collections.Generic;
 using Unity.Collections;
-using UnityEngine;
 
 namespace Unity.Netcode.RuntimeTests
 {

com.unity.netcode.gameobjects/Tests/Runtime/Messaging/MessageReceiveAllocationTests.cs

@@ -27,7 +27,7 @@ internal class MessageReceiveAllocationTests : NetcodeIntegrationTest
     {
         protected override int NumberOfClients => 1;
 
-        public MessageReceiveAllocationTests(HostOrServer hostOrServer) : base(hostOrServer) {}
+        public MessageReceiveAllocationTests(HostOrServer hostOrServer) : base(hostOrServer) { }
 
         private GameObject m_Prefab;