Fix Microsoft.CSharp dynamic code annotations

[eerhardt]

Summary

• annotate ComObject.RcwToComObject with RequiresDynamicCode
• propagate the requirement to ComMetaObject, which calls that method while constructing COM binding expressions

Reasoning

When creating an AOT-compatiblity test application, AOT analysis reports IL3050 from inside Microsoft.CSharp. RcwToComObject uses reflection to create a call to ObjectToComObject, which is annotated with both RequiresUnreferencedCode and RequiresDynamicCode. However, RcwToComObject only propagated RequiresUnreferencedCode. Propagating RequiresDynamicCode through RcwToComObject and ComMetaObject keeps the annotations consistent and prevents the warning from originating from an unannotated Microsoft.CSharp implementation path.

Testing

• dotnet build in src/libraries/Microsoft.CSharp
• dotnet build /t:test src/libraries/Microsoft.CSharp/tests/Microsoft.CSharp.Tests.csproj (2,648 passed)

Note

This pull request description was generated by GitHub Copilot.

[azure-pipelines]

Azure Pipelines:
Successfully started running 3 pipeline(s).
13 pipeline(s) were filtered out due to trigger conditions.
There may be pipelines that require an authorized user to comment /azp run to run.

[dotnet-policy-service]

Tagging subscribers to this area: @phil-allen-msft, @333fred
See info in area-owners.md if you want to be subscribed.

[Copilot]

Pull request overview

This PR aligns Microsoft.CSharp’s COM interop binder annotations with the actual dynamic-code requirements by marking the COM binding expression construction path as RequiresDynamicCode, so AOT analysis warnings originate from correctly annotated APIs.

Changes:

• Annotates ComObject.RcwToComObject with [RequiresDynamicCode(Binder.DynamicCodeWarning)] to match the dynamic-code requirement of the reflected ObjectToComObject target.
• Propagates [RequiresDynamicCode] onto ComMetaObject, which constructs binding expressions using RcwToComObject.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/libraries/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/ComInterop/ComObject.cs	Adds RequiresDynamicCode to RcwToComObject so the annotation matches the reflected call path used when building COM binding expressions.
src/libraries/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/ComInterop/ComMetaObject.cs	Adds RequiresDynamicCode to propagate the requirement to the caller that uses RcwToComObject during COM binding expression construction.

[333fred]

I know absolutely nothing about COM, so I'm tagging an expert to say if this seems reasonable @AaronRobinsonMSFT 🙂.

[AaronRobinsonMSFT]

Ugh. Yes, this seems appropriate. Sorry it was missed.

/cc @jkoritzinsky and @elinor-fung