[GHC] #8827: Inferring Safe mode with GeneralizedNewtypeDeriving is wrong

[GHC]

#8827: Inferring Safe mode with GeneralizedNewtypeDeriving is wrong
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        Reporter:  goldfire          |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  normal            |               Milestone:  7.12.1
       Component:  Compiler          |                 Version:  7.9
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:  #8226, #8745      |  Differential Revisions:
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Comment (by oerjan):

 I was hoping that the cutoff at explicit role annotations would mitigate
 the efficiency issue - presumably most major packages would have them, or
 the pragma to make implicit ones explicit.  Otherwise, perhaps the
 interface files could list the needed constructors for an implicit role
 parameter?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8827#comment:45>
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