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POHow can I debug heap errors in a C# class library?
 

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  1. POHow can I debug heap errors in a C# class library?
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    <p>I'm getting a heap corruption error in a C# library module I'm calling through COM in a C++ app. The specific error is:</p> <blockquote> <p>HEAP: Free Heap block 4b61bb8 modified at 4b61be8 after it was freed<BR> ...<BR> This may be due to a corruption of the heap, and indicates a bug in [app].exe or any of the DLLs it has loaded.</p> </blockquote> <p>The top of the call stack is:</p> <pre><code>CustomMarshalers.dll!System.Runtime.InteropServices.CustomMarshalers.EnumeratorViewOfEnumVariant.MoveNext() + 0x168 bytes </code></pre> <p>Now my understanding was that .NET was supposed to mitigate memory problems, not make more memory problems with were impossible to fix. Yet, I can't think of anything which I might be doing to cause a memory error, or how I would possibly go about trying to fix it. The particular module is using the Microsoft.VisualStudio.VCProjectEngine .NET components to iterate VC project files, with pretty simple iterators. It's breaking in a foreach statement while iterating Files in a VCProject filter (folder), after succeeding for the previous about 100 calls. The actual code which is breaking is:</p> <pre><code> IVCCollection CollectionFiles = (IVCCollection)FolderInProject.Files; foreach (VCFile File in CollectionFiles) { [...] } </code></pre> <p>How can I possibly go about debugging this?</p> <p>Update:</p> <p>When I call if from a pure C# Console app (no COM or native code involved), I get:</p> <blockquote> <p>An unhandled exception of type 'System.AccessViolationException' occurred in [component].dll<BR> <BR> Additional information: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.</p> </blockquote> <p>Still no clue how I could go about debugging this. Obviously there's a memory error happening somewhere... but how can I track it down in pure managed code where the memory model isn't even exposed?</p>
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    1. CODid you build a PIA for the COM module, or did you use a pre-built PIA?
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    2. COWhat's a PIA? I build the public interface, if that's what you're asking. I have build and used COM objects successfully before, and this one works if I return immediately; it only fails while using the VC .NET objects. Also, see my followup.
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    3. COPIA: http://msdn.microsoft.com/en-us/library/aax7sdch(VS.80).aspx
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