[GHC] #11771: ghc.exe: `panic'! (the 'impossible' happened); thread blocked indefinitely in an MVar operation

[GHC]

#11771: ghc.exe: `panic'! (the 'impossible' happened); thread blocked indefinitely
in an MVar operation
-------------------------------+----------------------------------------
        Reporter:  YoYoYonnY   |                Owner:
            Type:  bug         |               Status:  new
        Priority:  low         |            Milestone:
       Component:  GHCi        |              Version:  7.10.3
      Resolution:              |             Keywords:
Operating System:  Windows     |         Architecture:  Unknown/Multiple
 Type of failure:  GHCi crash  |            Test Case:
      Blocked By:              |             Blocking:
 Related Tickets:              |  Differential Rev(s):
       Wiki Page:              |
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Comment (by allmar):

 I got a similar crash with GHCi 8.0.1 on Windows 10 (64-bit). I also
 interrupted my running program (with Ctrl+C) right before the crash. My
 error message was as follows.

 {{{
 ghc.exe: panic! (the 'impossible' happened)
   (GHC version 8.0.1 for x86_64-unknown-mingw32):
         thread blocked indefinitely in an MVar operation

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
 }}}

 The crash has only happened once so far; I haven't been able to reproduce
 it.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11771#comment:1>
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