Panic in GHC 7.4.1

Test.hs

{-# LANGUAGE FunctionalDependencies #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE StandaloneDeriving #-}
{-# LANGUAGE UndecidableInstances #-}

module Test where

class C1 p q r | r -> p, r -> q
class C2 s
class C3 t

data Q = Q
data S r = S
data T1 s = T1

instance C1 p Q r => C2 (S r)
instance C2 s => C3 (T1 s)

newtype T2 r = T2 (T1 (S r))

deriving instance C1 p Q r => C3 (T2 r)

{-
GHC 7.4.1 results in a panic:

ghc.exe: panic! (the 'impossible' happened)
  (GHC version 7.4.1 for i386-unknown-mingw32):
        tcTyVarDetails
    ( p{tv aa4} [tv] :: ghc-prim:GHC.Prim.*{(w) tc 34d} )

Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

GHC 7.6.1-rc1 (7.6.0.20120810) compiles it without a problem.
-}