[GHC] #8767: Add rules involving `coerce` to the libraries

[GHC]

#8767: Add rules involving `coerce` to the libraries
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        Reporter:  nomeata                       |            Owner:
            Type:  task                          |           Status:  new
        Priority:  normal                        |        Milestone:  7.8.1
       Component:  libraries/base                |          Version:
      Resolution:                                |  7.8.1-rc2
Operating System:  Unknown/Multiple              |         Keywords:
 Type of failure:  None/Unknown                  |     Architecture:
       Test Case:                                |  Unknown/Multiple
  tests/simplCore/should_run/T2110.hs            |       Difficulty:
        Blocking:                                |  Unknown
                                                 |       Blocked By:  8718
                                                 |  Related Tickets:  #2110
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Comment (by ekmett):

 You can defintely have users write the rule for particular functors of
 course, but that means reasonably polymorphic code that is too complicated
 to INLINE will get penalized asymptotically, so in the long run I'd really
 like to find a better solution that might have a chance of firing on my
 code. ;)

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8767#comment:10>
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