ghc hung by FunctionalDependencies/UndecidableInstances

Hi, ghc seems to hang and eat memory when fed the following code: {-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies, UndecidableInstances #-} class C a b | a -> b where f :: a -> b newtype T a = T a instance (C a b, Eq b) => Eq (T a) where (==) = undefined g x = (undefined :: a -> a -> a -> ()) (T x) (f x) (undefined :: Eq a => a) Is this a bug? Best, Roland -- http://alacave.net/~roland/