[GHC] #8035: STM transaction left open if there is an orElse on the path between throwSTM and catchSTM

[GHC]

#8035: STM transaction left open if there is an orElse on the path between
throwSTM and catchSTM
-----------------------------+----------------------------------------------
Reporter:  errge             |          Owner:                  
    Type:  bug               |         Status:  new             
Priority:  normal            |      Component:  Runtime System  
 Version:  7.7               |       Keywords:  stm rts         
      Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
 Failure:  Runtime crash     |      Blockedby:                  
Blocking:                    |        Related:                  
-----------------------------+----------------------------------------------
 {{{
 main = join $ atomically $ do
   catchSTM
     (throwSTM ThreadKilled `orElse` return (putStrLn "wtf"))
     (\(e::SomeException) -> return (putStrLn "ok"))

 }}}

 This program crashes with a segmentation fault.  Tested with GHC HEAD.

 I attach the testcase and my proposed fix for the issue.  I've run the
 fast testsuite with the proposed fix without new defects.  On the other
 hand I'm very new to GHC, so while I'm sure in the defect and the test,
 the fix may be bogus.

 Thanks goes to Mihály Bárász for discovering the issue.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/8035>
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