[GHC] #5320: check_overlap panic (7.1 regression)

[GHC]

#5320: check_overlap panic (7.1 regression)
-----------------------------------+----------------------------------------
    Reporter:  mikhail.vorozhtsov  |        Owner:                    
        Type:  bug                 |       Status:  new               
    Priority:  normal              |    Milestone:                    
   Component:  Compiler            |      Version:  7.1               
    Keywords:                      |     Testcase:                    
   Blockedby:                      |   Difficulty:                    
          Os:  Unknown/Multiple    |     Blocking:                    
Architecture:  Unknown/Multiple    |      Failure:  Compile-time crash
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Comment(by mikhail.vorozhtsov):

 Now I'm getting
 {{{
 ghc: panic! (the 'impossible' happened)
   (GHC version 7.3.20110718 for x86_64-unknown-linux):
         ASSERT failed! file compiler/typecheck/TcErrors.lhs, line 590
 }}}
 after the "Overlapping instances ..." message.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5320#comment:7>
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