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{-# LANGUAGE CPP #-}
import Control.Concurrent
import Control.Exception
import Foreign
import System.IO (hFlush,stdout)
#if __GLASGOW_HASKELL__ < 705
import Prelude hiding (catch)
#endif
-- !!! Try to get two threads into a knot depending on each other.
-- This should result in the main thread being sent a NonTermination
-- exception (in GHC 5.02, the program is terminated with "no threads
-- to run" instead).
main = do
Foreign.newStablePtr stdout
-- HACK, because when these two threads get blocked on each other,
-- there's nothing keeping stdout alive so it will get finalized.
-- SDM 12/3/2004
let a = last ([1..10000] ++ [b])
b = last ([2..10000] ++ [a])
-- we have to be careful to ensure that the strictness analyser
-- can't see that a and b are both bottom, otherwise the
-- simplifier will go to town here, resulting in something like
-- a = a and b = a.
forkIO (print a `catch` \NonTermination -> return ())
-- we need to catch in the child thread too, because it might
-- get sent the NonTermination exception first.
r <- Control.Exception.try (print b)
print (r :: Either NonTermination ())
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