using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace ConsoleApplication6

{

class Program

{

public static ArgumentException FM(object s)

{

return new ArgumentException("aru");

}

static void Main(string[] args)

{

//逆变和协变

Func<object, ArgumentException> fn1 = FM;

Func<string, Exception> fn2 = fn1;

//里氏原则 Exception=ArgumentException 父类引用=子类对象的实例引用

Exception ret2= fn2("");

ArgumentException ret1= fn1("");

//ty的返回类型ArgumentException

var ty2 = ret2.GetType();

var ty1 = ret1.GetType();

//两个的实际类型都是System.ArgumentException

Console.WriteLine("ty1:"+ty1.ToString()+"\nty2:"+ty2.ToString());

Console.ReadKey();

}

}

}

原理图如下：