Impossible when deriving empty data declaration

When trying to load following code into GHCi I get an error:

ghc: panic! (the 'impossible' happened)
  (GHC version 6.12.3 for x86_64-unknown-linux):
	TcGenDeriv:mk_FunBind

Code is:

{-# LANGUAGE StandaloneDeriving, EmptyDataDecls #-}
module Test where
data Test
deriving instance Show (Test)

Probably Test cannot be made instance of Show but still error should be less fatal. ;-)

Trac metadata

Trac field	Value
Version	6.12.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC	mmitar@gmail.com
Operating system
Architecture