[GHC] #11008: Difficulties around inferring exotic contexts

[GHC]

#11008: Difficulties around inferring exotic contexts
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        Reporter:  crockeea          |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.2
      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 goldfire):

 I'm sorry -- I'm afraid I don't understand your last comment. Or, rather,
 my understanding leads me directly to the behavior we currently have:
 check derived instances for exotic contexts and reject if exotic, but skip
 the exotic-check for hand-written instances (including standalone-
 deriving). (Note that there is no GND in sight here -- just normal
 `deriving`.) Perhaps illustrate your idea with a few examples?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11008#comment:5>
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