[GHC] #9023: Error when using empty record update on binary pattern synonym

[GHC]

#9023: Error when using empty record update on binary pattern synonym
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        Reporter:  Iceland_jack  |            Owner:  cactus
            Type:  bug           |           Status:  patch
        Priority:  normal        |        Milestone:
       Component:  Compiler      |          Version:  7.8.2
      Resolution:                |         Keywords:
Operating System:  Linux         |     Architecture:  x86
 Type of failure:  None/Unknown  |       Difficulty:  Unknown
       Test Case:                |       Blocked By:
        Blocking:                |  Related Tickets:
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Comment (by archblob):

 I had no idea assertions were enabled only {{{-DDEBUG}}}, lesson learned.
 Here is the actual panic:
 {{{
 ghc-stage2: panic! (the 'impossible' happened)
   (GHC version 7.9.20140530 for x86_64-unknown-linux):
         ASSERT failed!
     file compiler/basicTypes/PatSyn.lhs line 268
     patSynInstArgTys P
     [t, t]
     [(t, t)]
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9023#comment:4>
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