[GHC] #14333: GHC doesn't use the fact that Coercible is symmetric

[GHC]

#14333: GHC doesn't use the fact that Coercible is symmetric
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        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.1
      Resolution:                    |             Keywords:  TypeFamilies,
                                     |  Roles
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #14323            |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by goldfire):

 Your patch solves a smaller problem than I was thinking of... but now I
 can't seem to think of it again. Regardless, your patch looks correct to
 me.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14333#comment:13>
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