Compiler Error CS1599

Method or delegate cannot return type 'type'

Some types in the .NET class library, for example, TypedReference, RuntimeArgumentHandle and ArgIterator cannot be used as return types because they can potentially be used to perform unsafe operations.

The following sample generates CS1599:

// CS1599.cs  
using System;  
  
class MyClass  
{  
   public static void Main()  
   {  
   }  
  
   public TypedReference Test1()   // CS1599  
   {  
      return null;  
   }  
  
   public ArgIterator Test2()   // CS1599  
   {  
      return null;  
   }  
}