Optimized/fixed marshaling for fields as there is no need to create a copied instance of the native object.

src/Generator/Generators/CLI/CLIMarshal.cs

@@ -185,8 +185,9 @@ namespace CppSharp.Generators.CLI
                 instance += "&";
 
             instance += Context.ReturnVarName;
+            var needsCopy = !(Context.Declaration is Field);
 
-            if (@class.IsRefType)
+            if (@class.IsRefType && needsCopy)
             {
                 var name = Generator.GeneratedIdentifier(Context.ReturnVarName);
                 Context.SupportBefore.WriteLine("auto {0} = new ::{1}({2});", name,

src/Generator/Generators/CLI/CLISourcesTemplate.cs

@@ -336,6 +336,7 @@ namespace CppSharp.Generators.CLI
 
                 var ctx = new MarshalContext(Driver)
                     {
+                        Declaration = decl,
                         ArgName = decl.Name,
                         ReturnVarName = variable,
                         ReturnType = decl.QualifiedType

src/Generator/Generators/Marshal.cs

@@ -19,6 +19,8 @@ namespace CppSharp.Generators
         public TextGenerator SupportBefore { get; private set; }
         public TextGenerator Return { get; private set; }
 
+        public Declaration Declaration { get; set; }
+
         public string ReturnVarName { get; set; }
         public QualifiedType ReturnType { get; set; }