[GHC] #10897: Incorrect ASSERT for buildPatSyn

[GHC]

#10897: Incorrect ASSERT for buildPatSyn
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        Reporter:  ezyang            |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  7.11
  checker)                           |             Keywords:
      Resolution:                    |  PatternSynonyms
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash                              |            Test Case:  patsyn/T10897
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by mpickering):

 For me this fails with

 {{{
 Declaration for Single:
   Iface type variable out of scope:  t
 Cannot continue after interface file error
 }}}

 I've had a poke around but the interface file stuff is a complete mystery
 for me. Someone else with more experience will have to look.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10897#comment:6>
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