[GHC] #8813: further support deriving instances Typeable1, Typeable2, etc

[GHC]

#8813: further support deriving instances Typeable1, Typeable2, etc
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        Reporter:  maeder                     |            Owner:
            Type:  task                       |           Status:  closed
        Priority:  normal                     |        Milestone:
       Component:  Compiler                   |          Version:
      Resolution:  wontfix                    |  7.8.1-rc1
Operating System:  Unknown/Multiple           |         Keywords:
 Type of failure:  GHC rejects valid program  |     Architecture:
       Test Case:                             |  Unknown/Multiple
        Blocking:                             |       Difficulty:  Unknown
                                              |       Blocked By:
                                              |  Related Tickets:
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Comment (by maeder):

 I quick test of adding a Typeable2 class ended with:
 {{{
 libraries/base/Data/Typeable/TypeableN.hs:1:1:
     Typeable instances can only be derived; replace the following
 instance:
       instance [overlap ok] Typeable2 a => Typeable a
         -- Defined at libraries/base/Data/Typeable/TypeableN.hs:32:10
 }}}
 So, at least, we do not need to worry about hand-written instances.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8813#comment:9>
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