Type equality class leads to non-termination

This program sends the type checker to the land of no return:

{-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies #-}
{-# LANGUAGE FlexibleInstances, FlexibleContexts #-}

module ShouldCompile where

class E a b | a -> b, b -> a
instance E a a

plus :: (E a (Int -> Int)) => Int -> a
plus x y = x + y

Trac metadata

Trac field	Value
Version	6.9
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler (Type checker)
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system	Unknown
Architecture	Unknown