[GHC] #12837: Disallow users to write instances for KnownNat and KnownSymbol

[GHC]

#12837: Disallow users to write instances for KnownNat and KnownSymbol
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        Reporter:  adamgundry        |                Owner:  sean
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:  fixed             |             Keywords:  newcomer
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC accepts       |  Unknown/Multiple
  invalid program                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D2898
       Wiki Page:                    |
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Changes (by mpickering):

 * status:  new => closed
 * resolution:   => fixed


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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12837#comment:7>
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