JIT编译器错误 - 无效的程序异常使用Reflection.Emit

Question

有人可以向我解释为什么以下工作的第一次测试，但引发第二次测试InvalidProgramException？我很难过。

using System; 
using System.Reflection; 
using System.Reflection.Emit;
 

namespace DMTest { class Program { static void Main(string[] args) { Test.NewResultWithParam(); Console.WriteLine("Press any key to continue"); Console.ReadLine(); Test.NewResult(); Console.WriteLine("Press any key to exit"); Console.ReadLine(); } }
 

public static class Test 
{ 
    public static void NewResult() 
    { 
     var f = typeof(Result).New<Result>(); 
     var result = f.Invoke(); 
    } 

    public static void NewResultWithParam() 
    { 
     var f = typeof(Result).New<Param, Result>(); 
     var result = f.Invoke(new Param("Parameter Executed")); 
     result.Build(); 
    } 
} 

public static class DynamicFunctions 
{ 
    public static Func<R> New<R>(this Type type) 
    { 
     if (!typeof(R).IsAssignableFrom(type)) 
     { 
      throw new ArgumentException(); 
     } 
     var dm = BuildNewMethod(type, Type.EmptyTypes); 
     return (Func<R>)dm.CreateDelegate(typeof(Func<R>)); 
    } 

    public static Func<T, R> New<T, R>(this Type type) 
    { 
     if (!typeof(R).IsAssignableFrom(type)) 
     { 
      throw new ArgumentException(); 
     } 
     var dm = BuildNewMethod(type, new Type[] { typeof(T) }); 
     return (Func<T, R>)dm.CreateDelegate(typeof(Func<T, R>)); 
    } 

    private static DynamicMethod BuildNewMethod(Type newObjType, Type[] parameterTypes) 
    { 
     var dm = new DynamicMethod("New_" + newObjType.FullName, newObjType, parameterTypes, newObjType); 
     var info = newObjType.GetConstructor(BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public, null, parameterTypes, new ParameterModifier[0]); 
     ILGenerator il = dm.GetILGenerator(); 
     il.Emit(OpCodes.Ldarg_0); 
     il.Emit(OpCodes.Newobj, info); 
     il.Emit(OpCodes.Ret); 
     return dm; 
    } 
} 

public class Result 
{ 
    private Param _param; 

    private Result() 
    { 
     Console.WriteLine("Parameterless constructor called"); 
    } 

    private Result(Param param) 
    { 
     Console.WriteLine("Parametered constructor called"); 
     _param = param; 
    } 

    public void Build() 
    { 
     _param.Execute(); 
    } 
} 

public class Param 
{ 
    private string _s; 

    public Param(string s) 
    { 
     _s = s; 
    } 

    public void Execute() 
    { 
     Console.WriteLine(_s); 
    } 
} 

}

Answer 1

il.Emit(OpCodes.Ldarg_0); // <-- problem here 

由于您的动态方法没有在New<T>版本的参数，你不能使用Ldarg_0。此外，Newobj将期望零参数，所以你的堆栈是不平衡的。