[GHC] #8745: GeneralizedNewtypeDeriving is still not Safe

[GHC]

#8745: GeneralizedNewtypeDeriving is still not Safe
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        Reporter:  goldfire          |            Owner:
            Type:  bug               |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  Compiler          |          Version:  7.8.1-rc1
      Resolution:                    |         Keywords:  Safe
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Comment (by goldfire):

 I had forgotten about this detail. With this in place (is it tested by
 anything in the testsuite?), I'm much more in favor of labeling GND and
 `coerce` as Safe. It's possible that the (rather draconian, admittedly)
 check that Joachim (nomeata) describes could be relaxed in the future once
 library authors are more familiar with role annotations.

 I no longer see a downside to making GND and `coerce` Safe.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8745#comment:4>
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