[GHC] #8892: Ghc panics (variable not found)

[GHC]

#8892: Ghc panics (variable not found)
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        Reporter:  jwlato              |            Owner:
            Type:  bug                 |           Status:  new
        Priority:  normal              |        Milestone:
       Component:  Compiler            |          Version:  7.8.1-rc2
      Resolution:                      |         Keywords:
Operating System:  Unknown/Multiple    |     Architecture:
 Type of failure:  Compile-time crash  |  Unknown/Multiple
       Test Case:                      |       Difficulty:  Unknown
        Blocking:                      |       Blocked By:
                                       |  Related Tickets:
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Comment (by simonpj):

 Yes, I'm sorry about the loop-breaker warnings -- you can safely ignore
 those.

 GHC should never produce an out-of-scope variable, so this is clearly a
 bug.

 Maybe you can try this:
  * Revert to -O not -O2
  * Remove individual optimsations, eg `-fno-full-laziness`, `-fno-spec-
 constr` etc
  * Remove code from the module being compiled so that it is as small as
 possible.
  * And then compile with `-dverbose-core2core -ddump-occur-anal -ddump-
 inlinings -ddump-rule-rewrites` (as well as `-dcore-lint` and save the
 output somewhere I can see it.

 Best of all would be to get a test case I can reproduce here.

 Thanks

 Simon

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8892#comment:3>
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