[GHC] #6130: Weak pointer to MVar is finalized, even though MVar is still accessible

[GHC]

#6130: Weak pointer to MVar is finalized, even though MVar is still accessible
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    Reporter:  jmillikin         |       Owner:                             
        Type:  bug               |      Status:  new                        
    Priority:  normal            |   Milestone:                             
   Component:  Compiler          |     Version:  7.4.1                      
    Keywords:                    |          Os:  Unknown/Multiple           
Architecture:  Unknown/Multiple  |     Failure:  Incorrect result at runtime
  Difficulty:  Unknown           |    Testcase:                             
   Blockedby:                    |    Blocking:                             
     Related:                    |  
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Changes (by simonmar):

  * difficulty:  => Unknown


Comment:

 I suspect this is just because the weak pointer is attached to the box,
 and not the primitive `MVar#` object underneath, and when optimisation is
 turned on GHC eliminates the box.  We should really have a `mkWeakMVar`
 operation, just like we have `mkWeakIORef` and `mkWeakThreadId`.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/6130#comment:1>
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