为什么C#编译器会生成错误,即使使用属性“SpecialName”

using System.Runtime.CompilerServices;

namespace ConsoleApplication21
{
    class Program
    {
        static void Main(string[] args)
        {
            int i = new MyClass1() - new MyClass1();
            int j = new MyClass1() + new MyClass1();
        }
    }

    public class MyClass1
    {
        public static int operator -(MyClass1 i,MyClass1 j)
        {
            return 5;
        }

        [SpecialName]
        public static int op_Addition(MyClass1 i,MyClass1 j)
        {
            return 5;
        }
    }
}

编译时错误：

Error 1 Operator ‘+’ cannot be applied to operands of type
‘ConsoleApplication21.MyClass1’ and ‘ConsoleApplication21.MyClass1’

所以,c#编译器不喜欢行“int j = new MyClass1()new MyClass1();”
当我打开ILDASM时,我得到了相同的运算符过载代码：

那么,为什么C#编译器会产生错误？
真的,奇怪的行为：如果我将MyClass1作为DLL引用,它工作正常！

谢谢！
Method #1 (
using System.Runtime.CompilerServices;

namespace ConsoleApplication21
{
    class Program
    {
        static void Main(string[] args)
        {
            int i = new MyClass1() - new MyClass1();
            int j = new MyClass1() + new MyClass1();
        }
    }

    public class MyClass1
    {
        public static int operator -(MyClass1 i,MyClass1 j)
        {
            return 5;
        }
    }
}

003)
 -------------------------------------------------------
 MethodName: op_Subtraction (
using System.Runtime.CompilerServices;

namespace ConsoleApplication21
{
    class Program
    {
        static void Main(string[] args)
        {
            int i = new MyClass1() - new MyClass1();
            int j = new MyClass1() + new MyClass1();
        }
    }

    public class MyClass1
    {
        public static int operator -(MyClass1 i,MyClass1 j)
        {
            return 5;
        }
    }
}

003)
 Flags : [Public] [Static] [HideBySig] [ReuseSlot] [SpecialName] (00000896)
 RVA : 0x00002078
 ImplFlags : [IL] [Managed] (00000000)
 CallCnvntn: [DEFAULT]
 ReturnType: I4
 2 Arguments
 Argument #1: Class ConsoleApplication21.MyClass1
 Argument #2: Class ConsoleApplication21.MyClass1
 2 Parameters
 (1) ParamToken : (

  

  
 
 
   
Error 1 Operator '+' cannot be applied to operands of type
 'ConsoleApplication21.MyClass1' and 'ConsoleApplication21.MyClass1'
 

  
002) Name : i flags: [none] (00000000)
 (2) ParamToken : (

  

  
 
 
   
Error 1 Operator '+' cannot be applied to operands of type
 'ConsoleApplication21.MyClass1' and 'ConsoleApplication21.MyClass1'
 

  
003) Name : j flags: [none] (00000000)
Method #2 (
using System.Runtime.CompilerServices;

namespace ConsoleApplication21
{
    class Program
    {
        static void Main(string[] args)
        {
            int i = new MyClass1() - new MyClass1();
            int j = new MyClass1() + new MyClass1();
        }
    }

    public class MyClass1
    {
        public static int operator -(MyClass1 i,MyClass1 j)
        {
            return 5;
        }
    }
}

004)
 -------------------------------------------------------
 MethodName: op_Addition (
using System.Runtime.CompilerServices;

namespace ConsoleApplication21
{
    class Program
    {
        static void Main(string[] args)
        {
            int i = new MyClass1() - new MyClass1();
            int j = new MyClass1() + new MyClass1();
        }
    }

    public class MyClass1
    {
        public static int operator -(MyClass1 i,MyClass1 j)
        {
            return 5;
        }
    }
}

004)
 Flags : [Public] [Static] [HideBySig] [ReuseSlot] [SpecialName] (00000896)
 RVA : 0x0000208c
 ImplFlags : [IL] [Managed] (00000000)
 CallCnvntn: [DEFAULT]
 ReturnType: I4
 2 Arguments
 Argument #1: Class ConsoleApplication21.MyClass1
 Argument #2: Class ConsoleApplication21.MyClass1
 2 Parameters
 (1) ParamToken : (

  

  
 
 
   
Error 1 Operator '+' cannot be applied to operands of type
 'ConsoleApplication21.MyClass1' and 'ConsoleApplication21.MyClass1'
 

  
004) Name : i flags: [none] (00000000)
 (2) ParamToken : (

  

  
 
 
   
Error 1 Operator '+' cannot be applied to operands of type
 'ConsoleApplication21.MyClass1' and 'ConsoleApplication21.MyClass1'
 

  
using System.Runtime.CompilerServices;

namespace ConsoleApplication21
{
    class Program
    {
        static void Main(string[] args)
        {
            int i = new MyClass1() - new MyClass1();
            int j = new MyClass1() + new MyClass1();
        }
    }

    public class MyClass1
    {
        public static int operator -(MyClass1 i,MyClass1 j)
        {
            return 5;
        }
    }
}using System.Runtime.CompilerServices;

namespace ConsoleApplication21
{
    class Program
    {
        static void Main(string[] args)
        {
            int i = new MyClass1() - new MyClass1();
            int j = new MyClass1() + new MyClass1();
        }
    }

    public class MyClass1
    {
        public static int operator -(MyClass1 i,MyClass1 j)
        {
            return 5;
        }
    }
}005) Name : j flags: [none] (00000000)