--Testing flexible and Overlapping instances
class C a where { f :: a -> Int; f _ = 3 }
instance C Int where { f = id }
instance C [Int]
:set -XFlexibleInstances
instance C [Int]
instance C a => C [a] where f xs = length xs
-- ***This should be an overlapping instances error!***
:set -XOverlappingInstances
instance C a => C [a] where f xs = length xs