在switch语句中抛出异常的堆栈跟踪中行号错误

本文关键字：跟踪 错误 堆栈 switch 语句 抛出异常 | 更新日期: 2023-09-27 18:14:36

我注意到异常堆栈跟踪中的行号有一个奇怪的行为，如果异常是在switch语句中抛出的。

下面是一个例子(由于行号的关系，格式当然很重要):

using System;
class Program {
    static void Main(string[] args) {
        for (int i = 0; i < 3; i++) {
            try {
                ThrowSomeException(i);
            } catch (Exception exc) {
                Console.WriteLine(exc);
            }
        }
    }
    private static void ThrowSomeException(int arg) {
        Console.WriteLine("arg = {0}", arg);
        switch (arg) {
        case 0:
            throw new Exception("Line number = 16");
        case 1:
            throw new Exception("Line number = 18");
        default:
            throw new Exception("Line number = 20");
        }
    }
}

堆栈跟踪中报告的行是switch语句中下一个异常所在的行。上面的程序产生如下结果(注意异常文本中的行号与堆栈跟踪中的行号不匹配):

arg = 0
System.Exception: Line number = 16
   at Program.ThrowSomeException(Int32 arg) in x:'test'Program.cs:line 18
   at Program.Main(String[] args) in x:'test'Program.cs:line 6
arg = 1
System.Exception: Line number = 18
   at Program.ThrowSomeException(Int32 arg) in x:'test'Program.cs:line 20
   at Program.Main(String[] args) in x:'test'Program.cs:line 6
arg = 2
System.Exception: Line number = 20
   at Program.ThrowSomeException(Int32 arg) in x:'test'Program.cs:line 20
   at Program.Main(String[] args) in x:'test'Program.cs:line 6

为什么会发生这种情况?

注意:我在VS 2012和2013上都试过了，在。net 3.5和4.5上编译，得到了相同的结果。

Debug vs Release:令人惊讶的是，我只在Debug中得到这个奇怪的行为，在Release中行号是正确的。

在switch语句中抛出异常的堆栈跟踪中行号错误

我试过反编译程序集，似乎程序集在两种模式下都做了一些优化。特别是第二个方法被改变了:

private static void ThrowSomeException(int arg)
{
    Console.WriteLine("arg = {0}", arg);
    switch (arg)
    {
        case 0:
        {
            throw new Exception("Line number = 16");
        }
        case 1:
        {
            throw new Exception("Line number = 18");
        }
    }
    throw new Exception("Line number = 20");
}

这是Telerik JustDecompile告诉我的方法在调试和发布模式下的样子。如果您查看原始程序集，很可能会有关于为什么存在这种差异的进一步解释。

我不知道如何继续，但我认为这是一个非常有趣的问题。我将把我的答案标记为Community Wiki，希望大家共同努力可以解决这个问题。

我又做了一些测试。我将ThrowSomeException()函数移动到一个单独的类中，并使其成为非静态的，这并没有改变任何东西。然后我稍微重写了一下，首先将异常赋值给一个变量，然后单独抛出它。

internal class Program
{
    private static void Main()
    {
        Test test = new Test();
        for (int i = 0; i < 3; i++)
        {
            try
            {
                test.ThrowSomeException(i);
            }
            catch (Exception exception)
            {
                Console.WriteLine(exception);
            }
        }
    }

}
public class Test
{
    public void ThrowSomeException(int arg)
    {
        Console.WriteLine("arg = {0}", arg);
        switch (arg)
        {
            case 0:
                {
                    Exception ex = new Exception("Line number = 36");
                    throw ex;
                }
            case 1:
                {
                    Exception ex = new Exception("Line number = 41");
                    throw ex;
                }
            default:
                {
                    Exception ex = new Exception("Line number = 46");
                    throw ex;
                }
        }
    }
}

以上代码在调试模式下有如下输出:

arg = 0
System.Exception: Line number = 36
   bij linenumbertest.Test.ThrowSomeException(Int32 arg) in c:'Users'nate'Docume
nts'Visual Studio 2012'Projects'linenumbertest'Program.cs:regel 40
   bij linenumbertest.Program.Main() in c:'Users'nate'Documents'Visual Studio 20
12'Projects'linenumbertest'Program.cs:regel 14
arg = 1
System.Exception: Line number = 41
   bij linenumbertest.Test.ThrowSomeException(Int32 arg) in c:'Users'nate'Docume
nts'Visual Studio 2012'Projects'linenumbertest'Program.cs:regel 45
   bij linenumbertest.Program.Main() in c:'Users'nate'Documents'Visual Studio 20
12'Projects'linenumbertest'Program.cs:regel 14
arg = 2
System.Exception: Line number = 46
   bij linenumbertest.Test.ThrowSomeException(Int32 arg) in c:'Users'nate'Docume
nts'Visual Studio 2012'Projects'linenumbertest'Program.cs:regel 47
   bij linenumbertest.Program.Main() in c:'Users'nate'Documents'Visual Studio 20
12'Projects'linenumbertest'Program.cs:regel 14

在Release模式下，第二个异常从第46行而不是第45行抛出。这种行为对于所有版本的。net框架和所有版本的vs都是一致的。我接下来将尝试使用VB项目来做这件事，看看它是否有区别。

编辑:使用以下VB项目在VS 2012中:

Module Program
Sub Main()
    Dim test As New Test()
    For i As Integer = 0 To 2
        Try
            test.ThrowSomeException(i)
        Catch exception As Exception
            Console.WriteLine(exception)
        End Try
    Next
End Sub
End Module
Public Class Test
Public Sub ThrowSomeException(arg As Integer)
    Console.WriteLine("arg = {0}", arg)
    Select Case arg
        Case 0
            If True Then
                Dim ex As New Exception("Line number = 22")
                Throw ex
            End If
        Case 1
            If True Then
                Dim ex As New Exception("Line number = 27")
                Throw ex
            End If
        Case Else
            If True Then
                Dim ex As New Exception("Line number = 32")
                Throw ex
            End If
    End Select
End Sub
End Class

问题没有发生，行号一致。

我还测试了直接由输出生成的可执行文件，并发现了更奇怪的结果。这是调试exe的输出:

arg = 0
System.Exception: Line number = 36
   bij linenumbertest.Test.ThrowSomeException(Int32 arg) in c:'Users'nate'Docume
nts'Visual Studio 2012'Projects'linenumbertest'Program.cs:regel 40
   bij linenumbertest.Program.Main() in c:'Users'nate'Documents'Visual Studio 20
12'Projects'linenumbertest'Program.cs:regel 14
arg = 1
System.Exception: Line number = 41
   bij linenumbertest.Test.ThrowSomeException(Int32 arg) in c:'Users'nate'Docume
nts'Visual Studio 2012'Projects'linenumbertest'Program.cs:regel 45
   bij linenumbertest.Program.Main() in c:'Users'nate'Documents'Visual Studio 20
12'Projects'linenumbertest'Program.cs:regel 14
arg = 2
System.Exception: Line number = 46
   bij linenumbertest.Test.ThrowSomeException(Int32 arg) in c:'Users'nate'Docume
nts'Visual Studio 2012'Projects'linenumbertest'Program.cs:regel 47
   bij linenumbertest.Program.Main() in c:'Users'nate'Documents'Visual Studio 20
12'Projects'linenumbertest'Program.cs:regel 14

这是释放模式exe的输出:

arg = 0
System.Exception: Line number = 36
   bij linenumbertest.Test.ThrowSomeException(Int32 arg) in c:'Users'nate'Docume
nts'Visual Studio 2012'Projects'linenumbertest'Program.cs:regel 41
   bij linenumbertest.Program.Main() in c:'Users'nate'Documents'Visual Studio 20
12'Projects'linenumbertest'Program.cs:regel 14
arg = 1
System.Exception: Line number = 41
   bij linenumbertest.Test.ThrowSomeException(Int32 arg) in c:'Users'nate'Docume
nts'Visual Studio 2012'Projects'linenumbertest'Program.cs:regel 42
   bij linenumbertest.Program.Main() in c:'Users'nate'Documents'Visual Studio 20
12'Projects'linenumbertest'Program.cs:regel 14
arg = 2
System.Exception: Line number = 46
   bij linenumbertest.Test.ThrowSomeException(Int32 arg) in c:'Users'nate'Docume
nts'Visual Studio 2012'Projects'linenumbertest'Program.cs:regel 37
   bij linenumbertest.Program.Main() in c:'Users'nate'Documents'Visual Studio 20
12'Projects'linenumbertest'Program.cs:regel 14

这与使用调试器运行此命令的结果不同。

快速测试似乎也表明异常和抛出语句之间的额外行(在这种情况下是console.writeline())也会影响结果:

重写为:

switch (arg)
    {
        case 0:
            {
                Exception ex = new Exception("Line number = 37");
                Console.WriteLine("case 0");
                throw ex;
            }
        case 1:
            {
                Exception ex = new Exception("Line number = 43");
                Console.WriteLine("case 1");
                throw ex;
            }
        default:
            {
                Exception ex = new Exception("Line number = 49");
                Console.WriteLine("case default");
                throw ex;                    
            }
    }

给出了VS的Release输出:

arg = 0
case 0
System.Exception: Line number = 37
   bij linenumbertest.Test.ThrowSomeException(Int32 arg) in c:'Users'nate'Docume
nts'Visual Studio 2012'Projects'linenumbertest'Program.cs:regel 43
   bij linenumbertest.Program.Main() in c:'Users'nate'Documents'Visual Studio 20
12'Projects'linenumbertest'Program.cs:regel 15
arg = 1
case 1
System.Exception: Line number = 43
   bij linenumbertest.Test.ThrowSomeException(Int32 arg) in c:'Users'nate'Docume
nts'Visual Studio 2012'Projects'linenumbertest'Program.cs:regel 49
   bij linenumbertest.Program.Main() in c:'Users'nate'Documents'Visual Studio 20
12'Projects'linenumbertest'Program.cs:regel 15
arg = 2
case default
System.Exception: Line number = 49
   bij linenumbertest.Test.ThrowSomeException(Int32 arg) in c:'Users'nate'Docume
nts'Visual Studio 2012'Projects'linenumbertest'Program.cs:regel 51
   bij linenumbertest.Program.Main() in c:'Users'nate'Documents'Visual Studio 20
12'Projects'linenumbertest'Program.cs:regel 15

和命令行输出:

arg = 0
case 0
System.Exception: Line number = 37
   bij linenumbertest.Test.ThrowSomeException(Int32 arg) in c:'Users'nate'Docume
nts'Visual Studio 2012'Projects'linenumbertest'Program.cs:regel 43
   bij linenumbertest.Program.Main() in c:'Users'nate'Documents'Visual Studio 20
12'Projects'linenumbertest'Program.cs:regel 15
arg = 1
case 1
System.Exception: Line number = 43
   bij linenumbertest.Test.ThrowSomeException(Int32 arg) in c:'Users'nate'Docume
nts'Visual Studio 2012'Projects'linenumbertest'Program.cs:regel 45
   bij linenumbertest.Program.Main() in c:'Users'nate'Documents'Visual Studio 20
12'Projects'linenumbertest'Program.cs:regel 15
arg = 2
case default
System.Exception: Line number = 49
   bij linenumbertest.Test.ThrowSomeException(Int32 arg) in c:'Users'nate'Docume
nts'Visual Studio 2012'Projects'linenumbertest'Program.cs:regel 39
   bij linenumbertest.Program.Main() in c:'Users'nate'Documents'Visual Studio 20
12'Projects'linenumbertest'Program.cs:regel 15

和VS的Debug输出:

arg = 0
case 0
System.Exception: Line number = 37
   bij linenumbertest.Test.ThrowSomeException(Int32 arg) in c:'Users'nate'Docume
nts'Visual Studio 2012'Projects'linenumbertest'Program.cs:regel 42
   bij linenumbertest.Program.Main() in c:'Users'nate'Documents'Visual Studio 20
12'Projects'linenumbertest'Program.cs:regel 15
arg = 1
case 1
System.Exception: Line number = 43
   bij linenumbertest.Test.ThrowSomeException(Int32 arg) in c:'Users'nate'Docume
nts'Visual Studio 2012'Projects'linenumbertest'Program.cs:regel 48
   bij linenumbertest.Program.Main() in c:'Users'nate'Documents'Visual Studio 20
12'Projects'linenumbertest'Program.cs:regel 15
arg = 2
case default
System.Exception: Line number = 49
   bij linenumbertest.Test.ThrowSomeException(Int32 arg) in c:'Users'nate'Docume
nts'Visual Studio 2012'Projects'linenumbertest'Program.cs:regel 51
   bij linenumbertest.Program.Main() in c:'Users'nate'Documents'Visual Studio 20
12'Projects'linenumbertest'Program.cs:regel 15

命令行输出如下:

arg = 0
case 0
System.Exception: Line number = 37
   bij linenumbertest.Test.ThrowSomeException(Int32 arg) in c:'Users'nate'Docume
nts'Visual Studio 2012'Projects'linenumbertest'Program.cs:regel 42
   bij linenumbertest.Program.Main() in c:'Users'nate'Documents'Visual Studio 20
12'Projects'linenumbertest'Program.cs:regel 15
arg = 1
case 1
System.Exception: Line number = 43
   bij linenumbertest.Test.ThrowSomeException(Int32 arg) in c:'Users'nate'Docume
nts'Visual Studio 2012'Projects'linenumbertest'Program.cs:regel 48
   bij linenumbertest.Program.Main() in c:'Users'nate'Documents'Visual Studio 20
12'Projects'linenumbertest'Program.cs:regel 15
arg = 2
case default
System.Exception: Line number = 49
   bij linenumbertest.Test.ThrowSomeException(Int32 arg) in c:'Users'nate'Docume
nts'Visual Studio 2012'Projects'linenumbertest'Program.cs:regel 51
   bij linenumbertest.Program.Main() in c:'Users'nate'Documents'Visual Studio 20
12'Projects'linenumbertest'Program.cs:regel 15
相关文章：