Unify.unifyTauTyLists: mismatched type lists!

[nobody]

the following simple code

-------------------------
data List elem =  Cons elem List | Nil

t1 :: List
t1 = Cons 1 Nil
-------------------------

causes (loaded within ghci):


ghc-6.4: 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/.

[simonpj]

Logged In: YES 
user_id=50165

Good bug; already fixed for the upcoming 6.4.1 release. (Try 
the release candidate to confirm.)