Include .winmd in nuget and enable C++ usage

[JohnMcPMS]

Summary of the Pull Request

Update the WSLC SDK nuget package for C++ usage.

PR Checklist

• Closes: Link to issue #xxx
• Communication: I've discussed this with core contributors already. If work hasn't been agreed, this work might be rejected
• Tests: Added/updated if needed and all pass
• Localization: All end user facing strings can be localized
• Dev docs: Added/updated if needed
• Documentation updated: If checked, please file a pull request on our docs repo and link it here: #xxx

Detailed Description of the Pull Request / Additional comments

Pipe the Microsoft.WSL.Containers winmd file through the build system and include it in the nuget package. Update the native targets to include a Reference for C++/WinRT to consume and generate headers for. Adds a fusion manifest fragment to allow RoGetActivationFactory to find the dll for the activatable types. Adds a property (WslcEnableCppWinRT) to disable all of this for pure C SDK usage.

Validation Steps Performed

Tested through a locally built nuget and sample project.

[Copilot]

Pull request overview

Updates the Microsoft.WSL.Containers SDK NuGet packaging/build integration to ship the WinRT metadata (.winmd) and enable C++/WinRT consumption (including activation via an injected manifest fragment).

Changes:

• Copies the generated wslcsdk.winmd to a stable bin output name (Microsoft.WSL.Containers.winmd) for packaging.
• Adds a WinRT activatable class manifest fragment and injects it into consuming native builds (opt-out via WslcEnableCppWinRT).
• Updates the NuGet spec and CI pipelines to include/stage the .winmd artifact.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/windows/WslcSDK/winrt/CMakeLists.txt	Post-build copies the generated WinMD into the bin layout used by NuGet packaging.
nuget/Microsoft.WSL.Containers/manifests/Microsoft.WSL.Containers.manifest	Adds a manifest fragment enumerating WinRT activatable classes in wslcsdk.dll.
nuget/Microsoft.WSL.Containers/build/native/Microsoft.WSL.Containers.targets	Adds a WinMD reference for C++/WinRT and injects the manifest fragment into native builds (toggle via WslcEnableCppWinRT).
nuget/Microsoft.WSL.Containers.nuspec.in	Includes Microsoft.WSL.Containers.winmd in the produced NuGet package.
.pipelines/package-stage.yml	Stages the .winmd into the expected per-arch bin layout during packaging.
.pipelines/build-job.yml	Publishes the .winmd into the per-arch SDK artifact drop.

[benhillis]

Looks pretty good, do .winmd files need to be signed?

[JohnMcPMS]

Looks pretty good, do .winmd files need to be signed?

They can be. It is possible that someone would want to include this one in their app if they need to marshal any of objects, but it isn't required.

[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 1 comment.

[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated no new comments.

[benhillis]

Signing off, imo anything we ship we should probably sign, but we can do that in a follow-up.

[JohnMcPMS]

Signing off, imo anything we ship we should probably sign, but we can do that in a follow-up.

I tried to update the PR to do it, but I'm not sure if I did so correctly. Will double check the nuget from the next release build for signed binaries all around.