[GHC] #1825: standalone deriving for typeable fails

[GHC]

#1825: standalone deriving for typeable fails
------------------------+---------------------------------------------------
 Reporter:  jpbernardy  |          Owner:  simonpj
     Type:  bug         |         Status:  new    
 Priority:  normal      |      Milestone:  6.8.2  
Component:  Compiler    |        Version:  6.8.1  
 Severity:  normal      |     Resolution:         
 Keywords:              |     Difficulty:  Unknown
 Testcase:              |   Architecture:  Unknown
       Os:  Unknown     |  
------------------------+---------------------------------------------------
Comment (by simonpj):

 PS: a smaller program that generates the error, when compiled with
 `-dcore-lint` is:
 {{{
 {-# OPTIONS -dcore-lint -XDeriveDataTypeable -XStandaloneDeriving #-}
 module Foo where
 data D a = C1 a | C2 (D a)
 deriving instance Typeable a => Typeable (D a)
 }}}

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1825#comment:2>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler