Standalone deriving of an unsupported class panics GHC

Using standalone deriving on a non-standard class, without GeneralizedNewtypeDeriving, causes GHC to panic. Here is an example:

{-# LANGUAGE StandaloneDeriving #-}

class C a
instance C Int

newtype T = T Int
deriving instance C T

Output:
ghc: panic! (the 'impossible' happened)
  (GHC version 6.12.1 for x86_64-unknown-linux):
	genDerivBinds: bad derived class main:Main.C{tc rdh}

Trac metadata

Trac field	Value
Version	6.12.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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