[GHC] #13943: Compiler infinite loop with GHC-8.2

[GHC]

#13943: Compiler infinite loop with GHC-8.2
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        Reporter:  vagarenko         |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  8.2.1-rc3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #12791            |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by dfeuer):

 mpickering, would this be fixed by preventing this mechanism from
 selecting overlappable instances? If so, maybe we should require an
 overlap pragma for any instance that will be overlapped.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13943#comment:5>
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