------------------------------------------------------------------
deriveStandalone :: LDerivDecl Name -> TcM (Maybe EarlyDerivSpec)
-- Standalone deriving declarations
--- e.g. deriving instance show a => Show (T a)
+-- e.g. deriving instance Show a => Show (T a)
-- Rather like tcLocalInstDecl
deriveStandalone (L loc (DerivDecl deriv_ty))
= setSrcSpan loc $