[GHC] #12654: Panic on interrupting the evaluation of foldl (\x a -> if x > 100 then 100 else x+a) 0 [1..]

2 Oct 2016


      #12654: Panic on interrupting the evaluation of foldl (\x a -> if x > 100 then 100
else x+a) 0 [1..]
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           Reporter:  Kuros          |             Owner:
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  GHCi           |           Version:  8.0.1
           Keywords:  ghci panic     |  Operating System:  Windows
  mvar thread block                  |
       Architecture:  x86_64         |   Type of failure:  GHCi crash
  (amd64)                            |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 Full log below (it only interrupted about a minute after i pressed ctrl-C,
 and I pressed it several times since it didn't respond):

 *Main> foldl (\x a -> if x > 100 then 100 else x+a) 0  [1..]
 Interrupted.
 *Main>
 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

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Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12654
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