[GHC] #13394: PatternSynonyms/OverloadedStrings regression in GHC HEAD

[GHC]

#13394: PatternSynonyms/OverloadedStrings regression in GHC HEAD
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        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  8.1
      Resolution:                    |             Keywords:
                                     |  PatternSynonyms
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Compile-time      |            Test Case:
  crash or panic                     |  polykinds/T13394
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"bc0f3abd0914808e33f84229818ab90842611bdd/ghc" bc0f3ab/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="bc0f3abd0914808e33f84229818ab90842611bdd"
 Deal with JoinIds before void types

 Trac #13394, comment:4 showed up another place where we were testing
 for the representation of of a type; and it turned out to be a JoinId
 which can be rep-polymorphic.

 Just putting the test in the right places solves this easily.
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13394#comment:5>
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