Generic instances for GHC AST

At the moment every part of the GHC AST derives instances of Data and Typeable. There are no instances of Generic. If I try to standalone derive these, the derivation eventually fails for deriving instance Generic (Name) because the constructors are not all in scope. So, does it make sense in GHC to at least derive Generic for the items that are opaque, and at most to do so for the whole AST. I know there were some concerns earlier about too many instances being derived, and its impact on compilation time and memory, so the minimal version may be best. This will allow the new generation libraries built around Generics to perform on GHC data structures too. Alan