[GHC] #14561: Panic on levity polymorphic very unsafe coerce

[GHC]

#14561: Panic on levity polymorphic very unsafe coerce
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        Reporter:  goldfire          |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.3
      Resolution:                    |             Keywords:
                                     |  LevityPolymorphism
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 Simon Peyton Jones <simonpj@…>):

 In [changeset:"e40db7b1676627f5291b463405338e7b69fa3f69/ghc"
 e40db7b1/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="e40db7b1676627f5291b463405338e7b69fa3f69"
 Detect levity-polymorphic uses of unsafeCoerce#

 This bug was shown up by Trac #14561. The deguarer carefully
 detects unsaturated and levity-polymorphic uses of primops,
 but not of things like unsafeCoerce#.

 The fix is simple: see Note [Levity-polymorphic Ids] in Id.
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14561#comment:6>
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