[GHC] #8406: Invalid object in isRetainer() or Segfault

[GHC]

#8406: Invalid object in isRetainer() or Segfault
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        Reporter:  crockeea        |                Owner:
            Type:  bug             |               Status:  infoneeded
        Priority:  normal          |            Milestone:  8.0.1
       Component:  Runtime System  |              Version:  7.8.3
      Resolution:                  |             Keywords:
Operating System:  Linux           |         Architecture:  x86_64 (amd64)
 Type of failure:  Runtime crash   |            Test Case:
      Blocked By:                  |             Blocking:
 Related Tickets:                  |  Differential Rev(s):
       Wiki Page:                  |
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Comment (by thomie):

 pally: I can not reproduce your problem. Which platform are you on? And
 how long does it take before your program crashes?

 Here's what I tried:
   * I'm using Ubuntu 14.04 Linux, x86-64.
   * I installed the following packages, after some trial and error:
 `libfftw3-dev libopenal-dev qtchooser qtbase5-dev qtdeclarative5-dev
 qtdeclarative5-qtquick2-plugin darcs`
   * `cabal sandbox init`
   * `darcs get http://hub.darcs.net/pallly/hdur`
   * `darcs get http://hub.darcs.net/komadori/HsQML`
   * `cabal install HsQML/`
   * `cabal install hdur/`
   * `.cabal-sandbox/bin/hdur` # Fails with some module not found error
 (frustrating! please fix, cabal install should have caught that)
   * I then installed `qml-module-qtquick2` from 15.04 (vivid). This also
 upgrade most other qt related packages
   * `.cabal-sandbox/bin/hdur`
   * I see a grey window with the subtext "foobar". When I press 'o', a
 black squiggly line appears on a white background.
   * No crash.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8406#comment:16>
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