[GHC] #10759: don't throw BlockedIndefinitelyOn... in main thread

[GHC]

#10759: don't throw  BlockedIndefinitelyOn... in main thread
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              Reporter:  yokto       |             Owner:
                  Type:  bug         |            Status:  new
              Priority:  normal      |         Milestone:
             Component:  Compiler    |           Version:  7.10.2
              Keywords:              |  Operating System:  Unknown/Multiple
          Architecture:              |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
             Test Case:              |        Blocked By:
              Blocking:              |   Related Tickets:
Differential Revisions:              |
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 In the main thread UserInterrupt can be thrown to unblock a thread.

 So the following program should wait for such an interrupt instead of
 throwing a BlockedIndefinitelyOnMVar exception

 {{{
 main = do
     var <- newEmptyMVar
     takeMVar var `catch`
         (const $ putStrLn "UserInterrupt caught" :: AsyncException -> IO
 ())
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10759>
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