VSIX extension for VS2012 not running when debugging

Question

I created a new VSIX extension project in Visual Studio 2012, and wrote a MEF classifier (as a test) that should simply highlight all text in a .mylang file. Here are the relevant parts of my .NET 4.5 code:

internal static class MyLangLanguage
{
    public const string ContentType = "mylang";

    public const string FileExtension = ".mylang";

    [Export(typeof(ClassificationTypeDefinition))]
    [Name(ContentType)]
    [BaseDefinition("code")]
    internal static ContentTypeDefinition MyLangSyntaxContentTypeDefinition = null;

    [Export]
    [FileExtension(FileExtension)]
    [ContentType(ContentType)]
    internal static FileExtensionToContentTypeDefinition MyLangSyntaxFileExtensionDefinition = null;
}

[Export(typeof(IClassifierProvider))]
[ContentType(MyLangLanguage.ContentType)]
[Name("MyLangSyntaxProvider")]
internal sealed class MyLangSyntaxProvider : IClassifierProvider
{
    [Import]
    internal IClassificationTypeRegistryService ClassificationRegistry = null;

    public IClassifier GetClassifier(ITextBuffer buffer)
    {
        return buffer.Properties.GetOrCreateSingletonProperty(() => new MyLangSyntax(ClassificationRegistry, buffer));
    }
}

internal sealed class MyLangSyntax : IClassifier { }

Here is the full code.

These are the relevant parts from my source.extension.vsixmanifest file. Based on suggestions and similar files I found across the web, I added the dependency on MPF and the two assets.

<?xml version="1.0" encoding="utf-8"?>
<PackageManifest Version="2.0.0" xmlns="http://schemas.microsoft.com/developer/vsx-schema/2011" xmlns:d="http://schemas.microsoft.com/developer/vsx-schema-design/2011">
    <!-- ... -->
    <Dependencies>
        <Dependency Id="Microsoft.Framework.NDP" DisplayName="Microsoft .NET Framework" d:Source="Manual" Version="4.5" />
        <Dependency d:Source="Installed" Id="Microsoft.VisualStudio.MPF.11.0" DisplayName="Visual Studio MPF 11.0" Version="[11.0,12.0)" />
    </Dependencies>
    <Assets>
        <Asset Type="Microsoft.VisualStudio.VsPackage" d:Source="Project" d:ProjectName="%CurrentProject%" Path="|%CurrentProject%;PkgdefProjectOutputGroup|" />
        <Asset Type="Microsoft.VisualStudio.MefComponent" d:Source="Project" d:ProjectName="%CurrentProject%" Path="|%CurrentProject%|" />
    </Assets>
</PackageManifest>

I also tried a version 1.0 manifest:

<?xml version="1.0" encoding="utf-8"?>
<Vsix Version="1.0.0" xmlns="http://schemas.microsoft.com/developer/vsx-schema/2010">
    <!-- ... -->
    <References />
    <Content>
        <MefComponent>|%CurrentProject%|</MefComponent>
    </Content>
</Vsix>

---

When I run it, it starts an experimental instance of Visual Studio 2012, and the Extensions and Updates window shows that my extension is active. However, it does not do anything when I load or create a .mylang file. Any exceptions I throw (as a test) from my extension are never thrown. Breakpoints are never hit, and get an exclamation mark with the following warning:

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

It feels as if my extension is never really loaded at all. My problem is similar to this problem and this problem, but I'm using Visual Studio 2012 which uses a new VSIX manifest format.

What I know:

• I can find my DLL and VSIX file in the %localappdata%\Microsoft\VisualStudio\11.0Exp\Extensions\MyLang\VSIXProject1\1.0 folder, so I know they are copied.
• Their timestamp corresponds to when I last built the project, so I know they are up-to-date.
• Project Properties > Debug > Start external program: is already automatically set to C:\Program Files (x86)\Microsoft Visual Studio 11.0\Common7\IDE\devenv.exe, and the Command line arguments were automatically set to /rootsuffix Exp.
• The Visual Studio log (created with the /log option) has two entries related to my extension: Successfully loaded extension... and Extension is enabled....
• My DLL does not appear on the Modules tab (list of all loaded DLLs) of the debugging Visual Studio, while some (not all) other extensions do appear.
• It doesn't get loaded in Visual Studio 2012 or 2010 both on my laptop and my desktop PC.

What I've tried:

• Set <IncludeAssemblyInVSIXContainer> to true in the .csproj file, per this suggestion, but it did not make any difference.
• I can't add the line <MefComponent>|%CurrentProject%|</MefComponent> to the source.extension.vsixmanifest file as it uses a different format (2.0) than VSIX projects for previous versions of Visual Studio (1.0).
• This suggestion (setting IncludeAssemblyInVSIXContainer and friends in my .csproj to true) but it does not make a difference. And my breakpoints are still showing the warning and not being hit.
• Reset the VS Experimental instance using the Reset the Visual Studio 2012 Experimental Instance shortcut in the Start Menu, as per this suggestion. It didn't make a difference.

How can I at the very least be sure my VSIX MEF extension is loaded and works? And if possible, how can I make by breakpoint work and debug it?

Answer 1

Edit: The problem is you've improperly exported your ContentTypeDefinition as a ClassificationTypeDefinition. You should use the following instead:

[Export] // <-- don't specify the type here
[Name(ContentType)]
[BaseDefinition("code")]
internal static ContentTypeDefinition MyLangSyntaxContentTypeDefinition = null;

---

Here's my two guesses right now:

1. Try removing the following line from your vsixmanifest. I assume you do not have a class in your project that extends Package, in which case Visual Studio might be refusing to load your package due to the following Asset line (your extension does not actually provide this asset).

   <Asset Type="Microsoft.VisualStudio.VsPackage" d:Source="Project" d:ProjectName="%CurrentProject%" Path="|%CurrentProject%;PkgdefProjectOutputGroup|" />
   

2. If that fails, try replacing your current source.extension.vsixmanifest with one written to the old schema (version 1.0). I know this form still works in Visual Studio 2012 because all ~20 extensions I work on (with >10 public releases) use the old schema.