[GHC] #8714: ExistentialQuantification plus DeriveDataTypeable leads to core lint error

[GHC]

#8714: ExistentialQuantification plus DeriveDataTypeable leads to core lint error
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        Reporter:  CoreyOConnor                  |            Owner:
            Type:  bug                           |           Status:  merge
        Priority:  highest                       |        Milestone:  7.8.1
       Component:  Compiler                      |          Version:
      Resolution:                                |  7.8.1-rc2
Operating System:  Unknown/Multiple              |         Keywords:
 Type of failure:  None/Unknown                  |     Architecture:
       Test Case:                                |  x86_64 (amd64)
  simplCore/should_compile/T8714                 |       Difficulty:
        Blocking:                                |  Unknown
                                                 |       Blocked By:
                                                 |  Related Tickets:
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Comment (by simonpj):

 Ha that'll teach me to make a last minute cosmetic change after
 validating.  Patch coming.

 S

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8714#comment:14>
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