Re: [GHC] #14070: Allow ‘unsafe’ deriving strategy, deriving code with ‘unsafeCoerce’

[GHC]

#14070: Allow ‘unsafe’ deriving strategy, deriving code with ‘unsafeCoerce’
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        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  feature request   |               Status:  closed
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:  duplicate         |             Keywords:
                                     |  QuantifiedConstraints, deriving
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #2893             |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 Remind me:
 {{{
   join_ = coerce @(forall a.   m (  m a) ->   m a)
 }}}
 Do we allow this?  (It's impredicative -- but in a benign way.)

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14070#comment:24>
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