GHC 7.8 chokes on recursive classes

Type checking this makes GHC 7.8.3 loop:

{-# LANGUAGE MultiParamTypeClasses #-}
module Foo where

class Class3 a => Class1 a where

class Class2 t a where
  class2 :: (Class3 t) => a -> m

class (Class1 t, Class2 t t) => Class3 t where

Does not happen in 7.6.3.

I think it's something to do with the Class3 constraint appearing in class2.

Trac metadata

Trac field	Value
Version	7.8.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler (Type checker)
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