[GHC] #14356: "Main: thread blocked indefinitely in an MVar operation" in fixIO

[GHC]

#14356: "Main: thread blocked indefinitely in an MVar operation" in fixIO
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        Reporter:  nickkuk           |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  low               |            Milestone:
       Component:  Runtime System    |              Version:  8.2.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Poor/confusing    |  Unknown/Multiple
  error message                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by dfeuer):

 * priority:  normal => low
 * failure:  Incorrect result at runtime => Poor/confusing error message


Comment:

 nickkuk, as alexbiehl sort of suggests, this is the expected behavior for
 the second example, although I think it would be worth trying to improve
 the error message. Unfortunately, your `mdo` example was stripped down too
 far to be able to interpret. Do you think you can provide a proper
 reproduction of what you see as bad `mdo` desugaring? I'll mark this low
 priority for the error message improvement; if you find a real desugaring
 problem we'll bump it back up.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14356#comment:6>
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