[GHC] #16208: map/coerce does not fire with all newtypes

[GHC]

#16208: map/coerce does not fire with all newtypes
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        Reporter:  monoidal          |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.6.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 Kryztoph, let me know if you need help diagnosing this.  Or maybe you
 already know what is going on.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16208#comment:1>
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