Tag Archives: Visual Studio

Unexpected precompiled header error C1859 on Windows 7

I’m one of the few developers at my company that is using Windows 7.  Most of the projects in the solution I am working with are C#, but some are C++.  Periodically I get the following error building every single source file in the C++ project on my machine:

fatal error C1859: 'Debug\MyProject.pch' unexpected precompiled header error, simply rerunning the compiler might fix this problem

Nothing I did seemed to solve the problem short of rebooting, which seems to be a common experience (see here and here).  Today I stumbled upon a post on the Visual C++ Team Blog that explains what is going on.

It turns out that the anti-malware improvements in Windows 7 are the culprit.  PCH files are implemented basically as a memory dump, including pointers.  This worked fine on previous versions of Windows, but Windows 7 upped the ante making this approach unworkable.

The new behavior that fixes this problem is available in Visual Studio 2010.  The Visual C++ team has also released a hotfix for Visual Studio 2008 SP1 with the fix.


Force .NET application to run in 32-bit process on 64-bit Windows

64-bit Windows has been around for a number of years, but there are a number of quirks that make it more difficult to work with than 32-bit Windows.  At my day job, I’m developing C# software on 64-bit Windows 7 using Visual Studio 2008 and I have to use some 32-bit DLLs provided by a third party.  We wrote some code to wrap these DLLs in C++, and I needed to debug into those wrappers.  When I tried to set a breakpoint in the C++ source code, instead of getting a filled in circle on the line indicating that the breakpoint will be hit, an empty circle with a yellow triangle in the corner is displayed.  Hovering over the icon displays a message indicating where the breakpoint is set and some text at the bottom explaining why the yellow triangle is being displayed:

The breakpoint will not currently be hit. No symbols have been loaded for this document.

Clearly this was due to trying to load a 32-bit DLL in a 64-bit process.  So the question is, how do you force a .NET application to run in a 32-bit process on 64-bit Windows?  Gabriel Schenker does a very nice job of describing the various ways of doing this.  I’ll summarize them here.

Set the platform target

When building a managed application in Visual Studio, you can specify the target platform to be either x86 or x64.

Visual Studio Platform Target x86

Setting this to x86 will force the target assembly (.dll or .exe) to be built as a 32-bit application, but if the assembly that loads the target assembly is running in a 64-bit process, it will fail to load your assembly.  Therefore, you need to make sure that if your application needs to load a 32-bit DLL that it is running in a 32-bit process.

Note that it is not required that you specify x86 to allow your assembly to be loaded in a 32-bit process.  If you specify Any CPU it can be loaded in either a 32-bit or a 64-bit process.

Force IIS to create a 32-bit app pool worker process

If your application is running as a web app, meaning it is running in an IIS app pool worker process, you’ll want that worker process (w3wp.exe) to be a 32-bit process.  That can be specified in the advanced settings of the app pool:

  1. Select the app pool for your web app.
  2. Click Advanced Settings… under Edit Application Pool on the right.
  3. Change the value of Enable 32-Bit Applications under (General) to True.

IIS Advanced Settings Enable 32-Bit Applications

Note that the word “Enable” in the setting doesn’t mean “allow” as in “allow either 32- or 64-bit applications.”  It actually means “force” as in “force the worker process to run in 32-bit mode so that 32-bit applications are supported.”  This means that the app pool worker process will always be launched as a 32-bit process when this setting has a value of True.  Setting it to False will launch a 64-bit app pool worker process.

Note that when an app pool worker process is started, it shows up in the Image Name column on the Processes tab in Task Manager as w3wp.exe.  When the Enable 32-Bit Applications setting has a value of True, it will be listed as w3wp.exe *32.

Modify the 32-bit flag in the assembly

This solution is intended for use by those that are not able to modify the build options.  The assembly header has a number of flags including one called 32BIT.  The CorFlags conversion tool allows you to modify the values of various flags, including the 32BIT flag.  You can use the following command to force the assembly to require a 32-bit process:

CorFlags MyAssembly.exe /32BIT+

The following command will clear the flag:

CorFlags MyAssembly.exe /32BIT-

Create a wrapper application

This solution allows you to make sure that you are running an application in a process with of a particular “bitness.”  Gabriel has a really good solution to this with source code in his post.

Additional Note

In my current position I end up having to attach to an existing w3wp.exe process to debug the web service.  Some of the web services are managed and some are managed/native.  Don’t forget to change the Attach to settings to include both Managed code and Native code.  However, this will only work when attaching to 32-bit processes.  Attempting to attach to a 64-bit process in this way will treat you to the following message:

Unable to attach to the process. Mixed mode debugging is not supported on Windows 64-bit platforms.


Removing trailing whitespace in Visual Studio

A pet peeve of mine is whitespace (spaces and tabs) at the end of lines in source code.  I used the SourceInsight editor when I worked at Microsoft which has a built-in feature (among other terrific features) to strip trailing whitespace when you save.  Visual Studio has plenty of other features that I can’t live without, so it was time to figure out how to add it there.

A decent solution is to add a subroutine to the EnvironmentEvents Module.  The articles I read made the assumption that anyone reading it would know where to find that.  I didn’t, so it took me some extra time to implement the feature.

Find EnvironmentEvents Module

The EnvironmentEvents Module is a macro module that is part of your Visual Studio environment and is accessible regardless of which project is loaded.  To edit that module, you need to bring up the Macros IDE, which can be launched at Tools » Macros » Macros IDE, or by pressing Alt+F11.

Macros IDE

In the Macros IDE you will see two entries in the Project Explorer (unless you’ve been here before and have been adding macros on your own):  MyMacros and Samples.  Double-click on MyMacros.  This will show you three entries:  References, EnvironmentEvents, and Module1.

Macros IDE Project Explorer - EnvironmentEvents

Double click on EnvironmentEvents.  You will now see the current contents of the EnvironmentEvents module.

Default EnvironmentEvents

DocumentEvents_DocumentSaved Subroutine

Now we come to the meat of the solution.  The idea is to implement the DocumentEvents_DocumentSaved subroutine to remove trailing whitespace.  This subroutine is called whenever a request is made to save a document.

Private Sub DocumentEvents_Documents(ByVal document As EnvDTE.Document) _
                                     Handles DocumentEvents.DocumentSaved
        ' Remove all the trailing whitespaces.
        If vsFindResult.vsFindResultReplaced = _
            DTE.Find.FindReplace( _
                            vsFindAction.vsFindActionReplaceAll, _
                            “{:b}+$”, _
                            vsFindOptions.vsFindOptionsRegularExpression, _
                            String.Empty, _
                            vsFindTarget.vsFindTargetFiles, _
                            document.FullName, , _
                            vsFindResultsLocation.vsFindResultsNone) Then
        End If
    Catch ex As Exception
        MsgBox(ex.Message, MsgBoxStyle.OkOnly, “Trim Whitespace exception”)
    End Try
End Sub

Once you’ve saved this, it will be immediately available to Visual Studio, whether it is open or not.

This subroutine searches for all instances of trailing whitespace (spaces and tabs) and replaces it with the empty string.  It works when you save an individual file and when you do a Save All.  If an error occurs in the FindReplace method, a message box will be displayed.

Thanks to Michael Urman, who posted this solution on StackOverflow.com (May 19 response).


Web application times out when debugging

I’ve been working on debugging the existing web applications my new company has developed.  I had everything set up, with the appropriate web applications created and breakpoints set, but after about 90 seconds Visual Studio would return to its non-debugging state.

It turns out that as of IIS6 (I’m using IIS 7 on Windows 7), IIS now pings worker processes to make sure it is still responsive, and if not the worker process is terminated.  There is a setting, however, to control this on the app pool.

IIS 7 App Pool Advanced Settings - Ping

  1. Select the app pool for your application.  This is one of the reasons why specifying a separate app pool for each web application is a good idea.
  2. Bring up Advanced Settings.
  3. Scroll down to the Process Model section.
  4. Change the value of the Ping Enabled setting to False.  Alternately you could change the Ping Maximum Response Time (seconds) setting to a higher value, but you’ll be limited in the amount of time you have to debug, so I don’t recommend that.

JohanS has a couple of really good articles on this, which go into more detail.