[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 itaibn):

 I had a similar crash in GHC 7.4.1. Also can't replicate. Full session:

 {{{
 GHCi, version 7.4.1: http://www.haskell.org/ghc/  :? for help
 Loading package ghc-prim ... linking ... done.
 Loading package integer-gmp ... linking ... done.
 Loading package base ... linking ... done.
 Prelude> 2**9
 512.0
 Prelude> 2^9
 512
 Prelude> 9^9
 387420489
 Prelude> 9^9^9
 ^C^C^C^C^C^C^C^C^C^C^CcInterPrelude>
 Prelude>
 ghc: panic! (the 'impossible' happened)
   (GHC version 7.4.1 for x86_64-unknown-linux):
         thread blocked indefinitely in an MVar operation

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

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11771#comment:2>
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