Authoring component with a class implementing a projected interface breaks source generation with incorrect function

[roxk]

Describe the bug
When authoring a component, if a public class implements a projected interface, source generator hard-error and emits It will not contribute to the output and compilation errors may occur as a result. Exception was of type 'Win32Exception' with message 'Incorrect function'.

To Reproduce

1. Clone roxk/packaged-oop-winrt-server-app-extension@d03f24e. The commit is currently the head of the csharp branch.
2. Open PackagedOOPWinRTServerAppExtension.sln and build AppExtensionCSharp
3. Observe warning CS8785 and compile error.

Expected behavior
It builds successfully. AppExtensionCSharp.WidgetProvider should implement SDK.IWidgetProvider in the generated winmd.

Version Info

  <PropertyGroup>
	<OutputType>WinExe</OutputType>
	<TargetFramework>net6.0-windows10.0.22621.0</TargetFramework>
	<TargetPlatformMinVersion>10.0.17763.0</TargetPlatformMinVersion>
	<Platforms>x64</Platforms>
	<RuntimeIdentifier>win10-x64</RuntimeIdentifier>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Microsoft.Windows.CsWinRT" Version="2.0.3" />
  </ItemGroup>

Additional context

1. Adding another internal class that implements projected interface works fine. It's only when the class is public (i.e. included in the generated winmd) source generator would freak out.
2. I'm working on a sample of implementing app extension point via OOP WinRT Server, to replace OOP COM Server. This bug is a show-stopper for C#. C++ as found in the repo above is working as expected.

[manodasanW]

@roxk Thanks for the repro. The issue is the WinRT authoring source generator needs to be able to find the WinMDs for any referenced components. In this case, it is failing to find the SDK component's WinMD due to it is not included in the referenced NuGet. If you include it in the referenced NuGet by doing something like below in the nuspec, you should see it build without issues. Feel free to reopen if you still run into issues.

<file src="..\..\x64\Release\SDK\SDK.winmd" target="lib\net6.0-windows10.0.22621.0\SDK.winmd" />