[GHC] #12727: ghc: panic! (the 'impossible' happened) - piResultTy

[GHC]

#12727: ghc: panic! (the 'impossible' happened) - piResultTy
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        Reporter:  ocharles          |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.2-rc1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by ocharles):

 Another panic that is different from all the above:

 {{{
 [231 of 278] Compiling Handler.Pallets  ( src/Handler/Pallets.hs,
 dist/build/Handler/Pallets.o )
 ghc: panic! (the 'impossible' happened)
   (GHC version 8.0.1.20161117 for x86_64-unknown-linux):
         getClassPredTys [Sql]
 }}}

 It's very strange that we seem to get different panics every time

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12727#comment:8>
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