GeneralizedNewtypeDeriving doesn't work with data families

[guest]

Observe:

{-# LANGUAGE TypeFamilies, GeneralizedNewtypeDeriving #-}
module Bug9 where

class C a where
    data D a

instance C Bool where
    newtype D Bool = DInt Int deriving (Eq, Show, Num)

The deriving of Num fails, whereas the corresponding standalone newtype works fine.

[simonpj]

Good point, thank you. Fixed by

Wed Dec 31 14:41:51 GMT 2008  simonpj@microsoft.com
  * Fix Trac #2856: make deriving work for type families

Merge this only if it's easy.

Simon

[igloo]

Merged