[GHC] #11172: Turning on optimisations produces SEGFAULT or Impossible case alternative

[GHC]

#11172: Turning on optimisations produces SEGFAULT or Impossible case alternative
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        Reporter:  nh2               |                Owner:  bgamari
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.0.1
       Component:  Compiler          |              Version:  7.10.2
      Resolution:                    |             Keywords:
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 bgamari):

 Alright, I am able to reproduce this on `master`,
 {{{
 $ git clone git://github.com/bgamari/impossible-case-alternative-repro
 repro
 $ cd repro
 $ git checkout segfault
 $ git clone git://github.com/bos/aeson
 $ cabal install aeson
 $ ghc -O Main.hs
 $ ./Main
 "before eval"
 Segmentation fault
 $
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11172#comment:17>
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