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

[GHC]

#8316: GHCi debugger segfaults when trying force a certain variable
------------------------------------+-------------------------------------
       Reporter:  guest             |             Owner:
           Type:  bug               |            Status:  new
       Priority:  normal            |         Milestone:
      Component:  GHCi              |           Version:  7.6.3
       Keywords:                    |  Operating System:  Unknown/Multiple
   Architecture:  Unknown/Multiple  |   Type of failure:  GHCi crash
     Difficulty:  Unknown           |         Test Case:
     Blocked By:                    |          Blocking:
Related Tickets:                    |
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 The file Test.hs has following definitions:
 {{{
 whnf :: a -> IO ()
 whnf a = a `seq` (return ())

 foo :: [Int]
 foo = [1..]
 }}}

 Calling ghci as:
 {{{
 ghci Test.hs -ignore-dot-ghci
 }}}

 and bebugging foo like this:
 {{{
 *Main> :b foo
 Breakpoint 0 activated at Test.hs:5:7-11
 *Main> foo
 Stopped at Test.hs:5:7-11
 _result :: [Int] = _
 [Test.hs:5:7-11] *Main> :p foo
 foo = (_t1::[Int])
 [Test.hs:5:7-11] *Main> whnf _t1
 }}}

 results in this segault:
 {{{
 <interactive>: internal error: TSO object entered!
     (GHC version 7.6.3 for x86_64_unknown_linux)
     Please report this as a GHC bug:
 http://www.haskell.org/ghc/reportabug
 [1]    5445 abort (core dumped)  ghci Test.hs -ignore-dot-ghci
 }}}

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