[GHC] #8503: New GeneralizedNewtypeDeriving check still isn't permissive enough

[GHC]

#8503: New GeneralizedNewtypeDeriving check still isn't permissive enough
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        Reporter:  goldfire          |            Owner:  goldfire
            Type:  bug               |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  Compiler          |          Version:  7.7
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:  8548
        Blocking:                    |  Related Tickets:  #8541
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Comment (by nomeata):

 My analysis in the previous comment was wrong; SPJ found out that the
 problem seems to lie in the calculation of defined and used variables for
 derived instances. Debugging...

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8503#comment:36>
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