Question

I am having a very odd problem with local variables being out of context in the Visual Studio 2010 debugger for a C# console application targeting .NET 4.0. I’ve searched for other similar questions on SO, but while some have the same symptoms, none seem to apply directly to this problem (they all appear to have other root causes).

The problem is that for some variables (but not all) I do not get a tooltip with their value, they do not appear in the Locals window, and I get “The name ‘xyz’ does not exist in the current context” if I add them to the Watch window. It appears to affect some variables but not others, and I can’t figure out a pattern (it doesn’t seem to be based on member vs. local, class vs. struct, or any other differentiator). I’ve restarted my computer and Visual Studio, verified I’m in a clean Debug build, made sure the debugging frame is correct, made sure to refresh the variables in the watch screen, and attempted various spells and incantations.

I’ve included a screenshoot below (bigger version at https://i.stack.imgur.com/JTFBT.png).

Any thoughts?

EDIT:

Adding some additional information:

The problem is repeatable. The exact same variables either work or don’t work, even after completely shutting down and restarting Visual Studio. This leads me to believe there’s actually something systematic going wrong rather than just memory corruption or something.

I’ve also discovered that it appears to be related to the try-catch block. If I position the breakpoint outside the try statement I can see any of the in-scope variables normally. As soon as the execution point enters the try statement all the variables outside the try block become inaccessible and I can only access the ones inside the try statement. It’s almost as though the debugger is treating the try block as a separate method (though you can see the code/compiler still does have access to in-scope variables). Has anyone seen this behavior before?

ANOTHER EDIT:

I (partially) take back what I said about the try-catch being suspect – it appears that in this portion of the code the debugger exhibits this odd taking stuff out of context for any enclosing block. For example, if I set a breakpoint directly inside the foreach statement in the screenshot I can see the “port” variable value on each iteration, but none of the variables outside the foreach statement (which disappear as soon as I enter the foreach block). Then as soon as you enter the try block, the “port” variable suddenly goes away. This is getting really weird.

Also, as requested, the code for the entire method is below.

private void ConfigureAnnouncerSockets(XDocument configDocument)
{
    XElement socketsElement = configDocument.XPathSelectElement("/Configuration/Network/AnnouncerSockets");
    bool useDefault = true;
    if (socketsElement != null)
    {
        //Use the default announcers? (they will be added at the end)
        XAttribute defaultAttribute = socketsElement.Attribute("useDefault");
        if (defaultAttribute != null)
        {
            useDefault = Convert.ToBoolean(defaultAttribute);
        }

        //Get the default frequency
        int defaultFrequency = Announcer.DefaultFrequency;
        XAttribute frequencyAttribute = socketsElement.Attribute("frequency");
        if (frequencyAttribute != null)
        {
            defaultFrequency = Convert.ToInt32(frequencyAttribute.Value);
        }

        //Get all sockets
        foreach (XElement socketElement in socketsElement.XPathSelectElements("./Socket"))
        {
            //Get the address
            IPAddress address = IPAddress.Broadcast;
            string addressAttribute = (string)socketElement.Attribute("address");
            if(!GetAddress(addressAttribute, ref address, true))
            {
                Intelliplex.Log.Warn("Invalid announcer socket address: " + addressAttribute);
                continue;
            }

            //Get the local address
            IPAddress localAddress = null;
            string localAddressAttribute = (string)socketElement.Attribute("localAddress");
            if(!GetAddress(localAddressAttribute, ref localAddress, false))
            {
                Intelliplex.Log.Warn("Invalid announcer socket local address: " + localAddressAttribute);
                continue;
            }

            //Get the port(s)
            List<int> ports = new List<int>();
            string[] ranges = ((string)socketElement.Attribute("port")).Split(new[] { ',' });
            foreach (string range in ranges)
            {
                string[] portPair = range.Split(new[] { '-' });
                int firstPort = Convert.ToInt32(portPair[0]);
                int lastPort = portPair.Length > 1 ? Convert.ToInt32(portPair[1]) : firstPort;
                do
                {
                    ports.Add(firstPort);
                } while (++firstPort <= lastPort);
            }

            //Get the local port
            int localPort = socketElement.Attribute("localPort") != null
                ? Convert.ToInt32((string)socketElement.Attribute("localPort")) : 0;

            //Get the frequency
            int frequency = socketElement.Attribute("frequency") != null
                ? Convert.ToInt32((string)socketElement.Attribute("frequency")) : defaultFrequency;

            //Create the socket(s) and add it/them to the manager
            foreach (int port in ports)
            {
                try
                {
                    IPEndPoint endPoint = new IPEndPoint(address, port);
                    IPEndPoint localEndPoint = localAddress == null
                        ? new IPEndPoint(IPAddress.Any, 0) : new IPEndPoint(localAddress, localPort);
                    Announcer socket = new Announcer(frequency, endPoint, localEndPoint);
                    AnnouncerSockets.Add(socket);
                }
                catch (Exception ex)
                {
                    Intelliplex.Log.Warn("Could not add announcer socket: " + ex.Message);
                }
            }
        }
    }

    //Add default announcement sockets?
    if (useDefault)
    {
        ConfigureDefaultAnnouncerSockets();
    }
}

Answer 1

So it turns out this is related to a bug in PostSharp. I had been using PostSharp but removed all aspects from my code and ensured that none were applied. I also verified with Reflector that the methods were intact in the assembly. However, it appears simply referencing PostSharp triggers some kind of manipulation of the debugging symbols that causes this problem. A (little) more information can be found here:

http://www.sharpcrafters.com/forum/Topic5794-21-1.aspx#bm7927

Also, in the release notes for the latest PostSharp hotfix states one of the fixed issues in hotfix 2.1.5.6 is “Debugging symbols: local variable symbols lost in implicit iterators.”

When I installed the latest and greatest PostSharp the problem went away and the universe returned to normal. Hopefully this question/answer will help anyone else using PostSharp who stumbles on this odd behavior before the next official PostSharp release. Make sure you’re on hotfix 2.1.5.6 or greater (given the severity of the bug, this probably should have been an actual release).

Thanks for all the help everyone.