APICompat should compare against a framework if it finds an empty folder for that framework.

[ericstj]

Is your feature request related to a problem? Please describe.

See https://github.com/dotnet/runtime/pull/111877/files#r2014992550

Describe the solution you'd like

This might be both a change to APICompat and a change to runtime. We need to make sure runtime resolves the references for a placeholder framework (similar to what maintenance-packages does) and then we need to make sure APICompat runs a comparison for that framework. This is probably relevant to maintenance-packages as well, where we have more cases of empty folders.

[dotnet-policy-service]

@dotnet/area-infrastructure-libraries a new issue has been filed in the ApiCompat area, please triage

[ViktorHofer]

Closing as dupe of #18165. I also have #27822 as a draft which I want to revive at some point.