Flags to produce full interface files and stop
-fno-code -fwrite-interface produces the interface files and stop, which is convenient for typechecking. The interface files produced with these flags do not contain unfoldings, which is not needed for typechecking. But when writing GHC Core plugins, we do need the unfoldings - so that the plugin has something to work with - but often don't need anything beyond the interface files.
I'm not aware of any flag or combination of flags that behaves like
-fno-code -fwrite-interface, but includes unfoldings in the interface files. So the proposal is to add such flag(s).