[GHC] #9611: Suggest the cause of "No instance" errors involving multiple versions of a package

[GHC]

#9611: Suggest the cause of "No instance" errors involving multiple versions of a
package
-------------------------------------+-------------------------------------
        Reporter:  rwbarton          |                Owner:  Yuras
            Type:  feature request   |               Status:  merge
        Priority:  normal            |            Milestone:  8.0.1
       Component:  Compiler          |              Version:  7.8.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect         |  Unknown/Multiple
  warning at compile-time            |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D1919
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Changes (by bgamari):

 * status:  patch => merge
 * failure:  None/Unknown => Incorrect warning at compile-time
 * milestone:   => 8.0.1


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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9611#comment:6>
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