[GHC] #5939: Standalone deriving Generic on type with instantiated arguments

[GHC]

#5939: Standalone deriving Generic on type with instantiated arguments
------------------------------+---------------------------------------------
 Reporter:  dreixel           |          Owner:  dreixel         
     Type:  bug               |         Status:  new             
 Priority:  normal            |      Component:  Compiler        
  Version:  7.4.1             |       Keywords:                  
       Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
  Failure:  None/Unknown      |       Testcase:                  
Blockedby:                    |       Blocking:                  
  Related:                    |  
------------------------------+---------------------------------------------
 Reiner Pope reports that the following code
 {{{
 {-# LANGUAGE DeriveGeneric, FlexibleInstances, StandaloneDeriving #-}
 import GHC.Generics
 data T a = T a
 deriving instance Generic (T Bool)
 }}}
 generates the following:
 {{{
 instance Generic (T Bool) where ...
 type instance Rep (T a) = ...
 }}}

 This is wrong. The type instance should probably be for `Rep (T Bool)`. Or
 perhaps we should refuse to derive Generic for instantiated types
 altogether.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5939>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler