Hi all,

In ghc 9.12-alpha the Enum instance for IoSubSystem no longer exists. I don't
see this change mentioned anywhere in the docs (release notes/changelog) here:
https://downloads.haskell.org/ghc/9.12.1-alpha1/docs/users_guide/9.12.1-notes.html

Was this change intended or was it a refactoring issue?

The datatype itself was moved from GHC.Internal.RTS.Flags to
GHC.Internal.IO.SubSystem.

The enum instance was earlier defined in GHC.Internal.RTS.Flags but now isn't
defined in either of the modules.

Best,
Adithya