Refactor abstract classes handling for scripting types creation (eg. Script or GPUResource) under dotnet7

Source/Engine/Engine/NativeInterop.cs

@@ -12,7 +12,6 @@ using System.Runtime.CompilerServices;
 using FlaxEngine.Assertions;
 using FlaxEngine.Utilities;
 using System.Runtime.InteropServices.Marshalling;
-using FlaxEngine.Visject;
 using System.Buffers;
 using System.Collections.Concurrent;
 using System.Text;
@@ -1845,10 +1844,12 @@ namespace FlaxEngine
         internal static IntPtr NewObject(IntPtr typeHandle)
         {
             Type type = Unsafe.As<Type>(GCHandle.FromIntPtr(typeHandle).Target);
-            if (type == typeof(Script))
+            if (type.IsAbstract)
             {
-                // FIXME: Script is an abstract type which can not be instantiated
-                type = typeof(VisjectScript);
+                // Dotnet doesn't allow to instantiate abstract type thus allow to use generated mock class usage (eg. for Script or GPUResource) for generated abstract types
+                var abstractWrapper = type.GetNestedType("AbstractWrapper", BindingFlags.NonPublic);
+                if (abstractWrapper != null)
+                    type = abstractWrapper;
             }
             object value = RuntimeHelpers.GetUninitializedObject(type);
             return GCHandle.ToIntPtr(GCHandle.Alloc(value));

Source/Engine/Visject/VisjectScript.cpp

@@ -1,6 +0,0 @@
-#include "VisjectScript.h"
-
-VisjectScript::VisjectScript(const SpawnParams& params)
-    : Script(params)
-{
-}

Source/Engine/Visject/VisjectScript.h

@@ -1,14 +0,0 @@
-// Copyright (c) 2012-2022 Wojciech Figat. All rights reserved.
-
-#pragma once
-
-#include "Engine/Scripting/Script.h"
-
-/// <summary>
-/// 
-/// </summary>
-API_CLASS(Namespace = "FlaxEngine.Visject") class FLAXENGINE_API VisjectScript : public Script
-{
-    API_AUTO_SERIALIZATION();
-    DECLARE_SCRIPTING_TYPE(VisjectScript);
-};

Source/Tools/Flax.Build/Bindings/BindingsGenerator.CSharp.cs

@@ -1227,6 +1227,10 @@ namespace Flax.Build.Bindings
 
             GenerateCSharpManagedTypeInternals(buildData, classInfo, contents, indent);
 
+            // Abstract wrapper (to ensure C# class can be created for Visual Scripts, see NativeInterop.NewObject)
+            if (classInfo.IsAbstract)
+                contents.AppendLine().Append(indent).Append("[Unmanaged] private sealed class AbstractWrapper : ").Append(classInfo.Name).AppendLine(" { }");
+
             // Nested types
             foreach (var apiTypeInfo in classInfo.Children)
             {