[GHC] #11760: runST with lazy blackholing breaks referential transparency

[GHC]

#11760: runST with lazy blackholing breaks referential transparency
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        Reporter:  Yuras             |                Owner:  dfeuer
            Type:  bug               |               Status:  patch
        Priority:  highest           |            Milestone:  8.2.1
       Component:  Core Libraries    |              Version:  7.10.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect result  |  Unknown/Multiple
  at runtime                         |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D3038
       Wiki Page:                    |
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Comment (by dfeuer):

 We still need a more reliable test case. I managed to make a variation of
 this one fail moderately reliably using lots more threads, but I have an
 idea for another approach that's probably cheaper and more reliable; I'll
 try to get to that shortly.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11760#comment:13>
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