GHC.Syb.Instances provides instances of Data/Typeable for Ghc Api types, using standalone deriving.

Most instances are standard; to provide Data instances abstract types, we use one of two schemes:

• no traversal: SrcSpan, Module, ModuleName, OccName, Name, FastString, DataCon, Var, TyCon, Class

    abstractConstr   n = mkConstr (abstractDataType n) ({abstract:++n++}) [] Prefix
    abstractDataType n = mkDataType n [abstractConstr n]

    instance Data SrcSpan where
      -- don't traverse?
      toConstr _   = abstractConstr SrcSpan
      gunfold _ _  = error gunfold
      dataTypeOf _ = mkNoRepType SrcSpan

• abstract traversal: NameSet, Bag

    instance Data NameSet where
      gfoldl k z s = z mkNameSet k nameSetToList s -- traverse abstractly
      toConstr _   = abstractConstr NameSet
      gunfold _ _  = error gunfold
      dataTypeOf _ = mkNoRepType NameSet

Please report any issues, either with these abstract instances or with these modules going out of sync with GHC head, to the package maintainer.