[GHC] #7296: ghc-7 assumes incoherent instances without requiring language `IncoherentInstances`

[GHC]

#7296: ghc-7 assumes incoherent instances without requiring language
`IncoherentInstances`
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              Reporter:  maeder      |            Owner:  simonpj
                  Type:  bug         |           Status:  new
              Priority:  normal      |        Milestone:  7.10.1
             Component:  Compiler    |          Version:  7.6.1
  (Type checker)                     |         Keywords:
            Resolution:              |     Architecture:  Unknown/Multiple
      Operating System:              |       Difficulty:  Unknown
  Unknown/Multiple                   |       Blocked By:
       Type of failure:  GHC         |  Related Tickets:  #9820
  accepts invalid program            |
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Changes (by goldfire):

 * related:  #8338 => #9820


Comment:

 See #9820 for another example of how this might happen. (I don't believe
 #8338 is related to this ticket.)

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7296#comment:7>
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