[GHC] #9043: Add missing type class instances for data types in GHC.Generics

[GHC]

#9043: Add missing type class instances for data types in GHC.Generics
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        Reporter:  ocharles          |            Owner:  dreixel
            Type:  feature request   |           Status:  patch
        Priority:  normal            |        Milestone:
       Component:  libraries/base    |          Version:  7.8.2
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Comment (by dreixel):

 I've had a look at this, and all seems fine to me. One caveat however:
 {{{
 instance (Data p, Data (f p), Typeable c, Typeable i, Typeable f) => Data
 (M1 i c f p) where
 }}}

 This `Typeable c` constraint will require changing the generation of
 `Generic` instances in GHC, because these `c`s are compiler-generated
 empty datatypes, which currently do not derive `Typeable`.

 Simon: what's the best way to do this? We need `Typeable` instances for
 the stuff generated by `mkBindsMetaD` in `TcGenGenerics`.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9043#comment:13>
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