[GHC] #15186: ghc 8.4.2 panic in profiling build

[GHC]

#15186: ghc 8.4.2 panic in profiling build
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        Reporter:  kquick            |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Profiling         |              Version:  8.4.2
      Resolution:                    |             Keywords:
Operating System:  Linux             |         Architecture:  x86_64
 Type of failure:  Compile-time      |  (amd64)
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by RyanGlScott):

 It turns out that `unsafeCoerce` isn't needed to reproduce the issue,
 fortunately. I've edited comment:1 accordingly.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15186#comment:2>
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