[GHC] #8316: GHCi debugger segfaults when trying force a certain variable

[GHC]

#8316: GHCi debugger segfaults when trying force a certain variable
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        Reporter:  guest             |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:
       Component:  GHCi              |              Version:  7.6.3
      Resolution:                    |             Keywords:  debugger
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  GHCi crash        |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by osa1):

 Simon, I implemented changes in `cvObtainTerm` as discussed yesterday, but
 I'm still getting "TSO object entered" errors.

 Previously `cvObtainTerm` follwed indirectee's of BLACKHOLEs no matter
 what.

 With my changes I only follow the indirectees when they're not TSO or
 BLOCKING_QUEUE. Somehow with this I still get "TSO object entered".

 If I don't follow BLACKHOLE indirectees at all (and bind a BLACKHOLE to
 `_t1` in this reproducer) then I get a deadlock as expected. Do you have
 any ideas on why this may be happening?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8316#comment:8>
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