[GHC] #8205: the 'impossible' happened : expectJust block_order

[GHC]

#8205: the 'impossible' happened : expectJust block_order
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        Reporter:  erikd                |            Owner:
            Type:  bug                  |           Status:  new
        Priority:  normal               |        Milestone:
       Component:  Compiler             |          Version:  7.7
      Resolution:                       |         Keywords:
Operating System:  Unknown/Multiple     |     Architecture:
 Type of failure:  Building GHC failed  |  Unknown/Multiple
       Test Case:                       |       Difficulty:  Unknown
        Blocking:                       |       Blocked By:
                                        |  Related Tickets:
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Comment (by jstolarek):

 OK, I'm really puzzled about this segfault in stage2 compiler, but perhaps
 I can help with panic in `expectJust` - we need to reproduce it. This
 means you need to revert the reverting commit :) or in other words attempt
 to build unmodified HEAD and allow stage1 build to fail with panic that
 you originally reported. After that happens run the command that causes
 the segfault with `-ddump-cmm -dcmm-lint` added.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8205#comment:11>
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