[GHC] #15636: Implication constraint priority breaks default class implementations

[GHC]

#15636: Implication constraint priority breaks default class implementations
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        Reporter:  i-am-tom          |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler          |              Version:  8.6.1-beta1
      Resolution:                    |             Keywords:
                                     |  QuantifiedConstraints
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC rejects       |  Unknown/Multiple
  valid program                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by i-am-tom):

 Not at all - if this is intended behaviour, I'm happy to close the ticket.
 Thanks for the explanation!

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15636#comment:2>
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