Bugs with fundeps

[Marcin 'Qrczak' Kowalczyk]

The following program is accepted and prints [102]:

------------------------------------------------------------------------
class Foo a b | a -> b where
    foo :: a -> b
instance Foo [a] (Maybe a) where
    foo []    = Nothing
    foo (x:_) = Just x
instance Foo (Maybe a) [a] where
    foo Nothing  = []
    foo (Just x) = [x]
test3:: [a] -> [b]
test3 = foo . foo
main:: IO ()
main = print (test3 "foo" :: [Int])
------------------------------------------------------------------------

The following module causes a panic:
basicTypes/Var.lhs:185: Non-exhaustive patterns in function readMutTyVar

------------------------------------------------------------------------
module M1 where
class HasFoo a foo | a -> foo where
    foo :: a -> foo
instance HasFoo Int Int where
    foo = id
instance HasFoo a b => HasFoo [a] b where
    foo = foo . head
test:: [[Int]] -> Int
test = foo
------------------------------------------------------------------------

-- 
 __("<  Marcin Kowalczyk * qrczak@knm.org.pl http://qrczak.ids.net.pl/
 \__/
  ^^                      SYGNATURA ZASTĘPCZA
QRCZAK