ILGenerator捕获异常不起作用

Question

我正在使用System.Reflection.Emit为类型生成包装器。在某种程度上，可能是原始对象在访问时抛出错误( FaultException )，并且错误应该被我已经实现的try { } catch (Exception e) { }捕获，但它没有。

代码由ILSpy正确显示。

try
{
    if (original.Station != null)
    {
        if (objectDictionary.ContainsKey(original.Station))
        {
            this.Station = (objectDictionary[original.Station] as StationWrapper);
        }
        else
        {
            this.Station = new StationWrapper(original.Station, objectDictionary);
        }
    }
}
catch (Exception arg_6D_0)
{
    ReportManager.Log(arg_6D_0);
}

代码生成

这是程序集生成的代码。

Label ex = il.BeginExceptionBlock();
....
// Exception block end
il.Emit(OpCodes.Leave, ex);
il.BeginCatchBlock(typeof(Exception));
il.Emit(OpCodes.Call, ReportManager_Log);
il.EndExceptionBlock();

编辑

例外是被用户代码捕获，而不是被IL-Code捕获。

拆卸

在这里删除了客户的一些命名空间。写入行已在最后几分钟添加。

.try
{
    IL_0019: ldarg.1
    IL_001a: call instance class [...]...Station [...]...StationBase::get_Station()
    IL_001f: brfalse IL_0063

    IL_0024: ldarg.2
    IL_0025: ldarg.1
    IL_0026: call instance class [...]...Station [...]...StationBase::get_Station()
    IL_002b: call instance bool class [mscorlib]System.Collections.Generic.Dictionary`2<object, object>::ContainsKey(!0)
    IL_0030: brfalse IL_0051

    IL_0035: ldarg.0
    IL_0036: ldarg.2
    IL_0037: ldarg.1
    IL_0038: call instance class [...]...Station [...]...StationBase::get_Station()
    IL_003d: call instance !1 class [mscorlib]System.Collections.Generic.Dictionary`2<object, object>::get_Item(!0)
    IL_0042: isinst ...StationWrapper
    IL_0047: call instance void ...StationBaseWrapper::set_Station(class ...StationWrapper)
    IL_004c: br IL_0063

    IL_0051: ldarg.0
    IL_0052: ldarg.1
    IL_0053: call instance class [...]...Station [...]...StationBase::get_Station()
    IL_0058: ldarg.2
    IL_0059: newobj instance void ....StationWrapper::.ctor(class [...]...Station, class [mscorlib]System.Collections.Generic.Dictionary`2<object, object>)
    IL_005e: call instance void ...StationBaseWrapper::set_Station(class ...StationWrapper)

    IL_0063: leave IL_007c
} // end .try
catch [mscorlib]System.Exception
{
    IL_0068: ldstr "Its comming home"
    IL_006d: call void [mscorlib]System.Console::WriteLine(string)
    IL_0072: call void [...Report]...ReportManager::Log(class [mscorlib]System.Exception)
    IL_0077: leave IL_007c
} // end handler

编辑2

当在IL代码中抛出System.Exception时，在FaultException'1可以发生之前，异常正在被处理。已使用Exception和ArgumentException进行测试。

Answer 1

这实际上似乎是Visual-Studio2010的一个bug。所有异常在VS中被捕获时都会被忽略，但VS无论如何都会显示异常。

并不是所有的异常都被忽略，这似乎取决于抛出异常的代码。生成的异常(通过Emit )将被忽略，来自外部DLL的异常不会被忽略。

Answer 2

这里一切正常；你确定它不是一个嵌套的异常块吗？

示例：

using System;
using System.Reflection.Emit;

public class Test
{
    static void Main()
    {
        var dm = new DynamicMethod("foo", null, new[] {typeof(bool)});
        var il = dm.GetILGenerator();

        Label ex = il.BeginExceptionBlock();
        il.Emit(OpCodes.Ldarg_0);
        il.EmitCall(OpCodes.Call, typeof(Test).GetMethod("Throw"), null);
        il.Emit(OpCodes.Leave, ex);

        il.BeginCatchBlock(typeof(Exception));
        il.EmitCall(OpCodes.Call, typeof(Test).GetMethod("Log"), null);
        il.EndExceptionBlock();
        il.Emit(OpCodes.Ldstr, "done");
        il.EmitCall(OpCodes.Call, typeof(Console).GetMethod("WriteLine",
                      new[] {typeof(string)}), null);

        il.Emit(OpCodes.Ret);
        var act = (Action<bool>)dm.CreateDelegate(typeof (Action<bool>));
        Console.WriteLine("Expect success:");
        act(false);
        Console.WriteLine("Expect fail:");
        act(true);
        Console.WriteLine("(all done)");
    }
    public static void Throw(bool fatal)
    {
        if(fatal) throw new InvalidOperationException("Boom!");
    }
    public static void Log(Exception ex)
    {
        Console.WriteLine("Error: " + ex.Message);
    }
}