[GHC] #4283: Different behaviour with -O in concurrent program

[GHC]

#4283: Different behaviour with -O in concurrent program
---------------------------------+------------------------------------------
    Reporter:  simonpj           |        Owner:  simonmar    
        Type:  bug               |       Status:  new         
    Priority:  normal            |    Milestone:  6.16.1      
   Component:  Compiler          |      Version:  6.12.3      
    Keywords:                    |     Testcase:              
   Blockedby:                    |   Difficulty:              
          Os:  Unknown/Multiple  |     Blocking:              
Architecture:  Unknown/Multiple  |      Failure:  None/Unknown
---------------------------------+------------------------------------------
 Mitar (mmitar at gmail.com) reports
 I am attaching a program which locks (throws an exception <<loop>>) when
 compiled like:
 {{{
 ghc --make -threaded -main-is Test.main Test.hs -o test
 }}}
 and doesn't lock when compiled with
 {{{
 ghc --make -threaded -main-is -O2 Test.main Test.hs -o test
 }}}
 This should probably not happen.

 I am using 6.12.3 on Linux x86_64.

 I reproduced this with the HEAD:
 {{{
 simonpj at cam-04-unx:~/tmp$ ./test-opt
 42
 42
 42
 42
 -- Ctrl-C out
 simonpj at cam-04-unx:~/tmp$ ./test-no-opt
 42
 test-no-opt: <<loop>>
 /bin/bash: line 0: echo: write error: Broken pipe
 /bin/bash: line 0: echo: write error: Broken pipe
 /bin/bash: line 0: echo: write error: Broken pipe
 -- Ctrl-C out
 }}}
 It's not 100% clear that it's a bug, but Simon M will look at it.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4283>
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