[GHC] #9456: Weird behavior with polymorphic function involving existential quantification and GADTs

[GHC]

#9456: Weird behavior with polymorphic function involving existential
quantification and GADTs
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              Reporter:  haasn       |            Owner:
                  Type:  bug         |           Status:  new
              Priority:  normal      |        Milestone:
             Component:  Compiler    |          Version:  7.8.2
  (Type checker)                     |         Keywords:
            Resolution:              |     Architecture:  Unknown/Multiple
      Operating System:              |       Difficulty:  Unknown
  Unknown/Multiple                   |       Blocked By:
       Type of failure:  GHC         |  Related Tickets:
  rejects valid program              |
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Comment (by rwbarton):

 (I noticed the GADTs section of the User's Guide was out of date regarding
 the flags turned on by `-XGADTs`, fixed in
 b287bc9bd0afaa26fcd3fe53a49bf86deeb868d8.)

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9456#comment:6>
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