[GHC] #9117: Coercible constraint solver misses one

[GHC]

#9117: Coercible constraint solver misses one
-------------------------------------+------------------------------------
        Reporter:  goldfire          |            Owner:  nomeata
            Type:  bug               |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  Compiler          |          Version:  7.8.2
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Comment (by goldfire):

 Your non-terminating `Foo` example seems pathological, but what about
 this, somewhat more sensible example:

 {{{
 newtype Bar a = Bar (Either a (Bar a))

 x :: Bar Age
 x = coerce (Bar (Left (5 :: Int)))
 }}}

 This example works in 7.8.2.

 PS: Will contribute to the "Coercible" page in due course. Thanks for
 starting it.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9117#comment:21>
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