[GHC] #5007: "deriving" seems to ignore class context for a type family

[GHC]

#5007: "deriving" seems to ignore class context for a type family
-------------------------------------------------------------------------+--
    Reporter:  jkff                                                      |        Owner:  simonpj                  
        Type:  bug                                                       |       Status:  new                      
    Priority:  high                                                      |    Milestone:  7.2.1                    
   Component:  Compiler (Type checker)                                   |      Version:  7.0.2                    
    Keywords:  type families, datatype contexts, type classes, deriving  |     Testcase:                           
   Blockedby:                                                            |   Difficulty:                           
          Os:  Unknown/Multiple                                          |     Blocking:                           
Architecture:  Unknown/Multiple                                          |      Failure:  GHC rejects valid program
-------------------------------------------------------------------------+--
Changes (by igloo):

  * owner:  => simonpj
  * priority:  normal => high
  * milestone:  => 7.2.1


Comment:

 Simon, is this the expected behaviour?

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5007#comment:1>
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