[GHC] #16310: Program fails with "Impossible case alternative" when optimized

[GHC]

#16310: Program fails with "Impossible case alternative" when optimized
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        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.6.3
      Resolution:                    |             Keywords:  TypeInType
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Runtime crash     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by RyanGlScott):

 Upon further searching, the most likely reason why this fails Core Lint in
 GHC 8.2.2 but not in later versions is due to commit
 6b52b4c832f888f7741a4ba0fec1fdac10244f6d, which removed the very Core Lint
 check that fires in 8.2.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16310#comment:1>
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