[GHC] #12373: Type error but types match

[GHC]

#12373: Type error but types match
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        Reporter:  osa1              |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.1
  checker)                           |
      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):

 Yes, well spotted.  It would be great to nail this since it keeps popping
 up.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12373#comment:3>
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