buggy class causes unifyTauTyLists mismatch

Obtained error in GHC:

Compiling Main             ( test.hs, interpreted )
ghc.exe: panic! (the `impossible' happened, GHC version
6.4):
        Unify.unifyTauTyLists: mismatched type lists!

Please report it as a compiler bug to
glasgow-haskell-bugs@haskell.org,
or http://sourceforge.net/projects/ghc/.

when :load called on buggy code:

class Foo f where
	baa :: f a -> f
instance Foo Maybe where
	baa z = z

On the other hand, Hugs identifies an error with an
"Illegal type in constructor application".

Trac metadata

Trac field	Value
Version	None
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	ResolvedFixed
Component	Compiler
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