[GHC] #8128: Standalone deriving fails for GADTs due to inaccessible code

[GHC]

#8128: Standalone deriving fails for GADTs due to inaccessible code
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        Reporter:  adamgundry                 |            Owner:
            Type:  bug                        |           Status:  new
        Priority:  normal                     |        Milestone:
       Component:  Compiler (Type checker)    |          Version:  7.7
      Resolution:                             |         Keywords:
Operating System:  Unknown/Multiple           |     Architecture:
 Type of failure:  GHC rejects valid program  |  Unknown/Multiple
       Test Case:                             |       Difficulty:  Unknown
        Blocking:                             |       Blocked By:
                                              |  Related Tickets:
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Comment (by monoidal):

 @carter: Regarding `Typeable 'Z`, you just need to write `deriving
 instance Typeable 'Z` and likewise for 'N. I don't know what's going on
 with `Data`.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8128#comment:6>
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