[GHC] #9424: ghc-api/T8628 fails assert on debugged ghc

[GHC]

#9424: ghc-api/T8628 fails assert on debugged ghc
-------------------------------------+-------------------------------------
       Reporter:  slyfox             |                   Owner:
           Type:  bug                |                  Status:  new
       Priority:  normal             |               Milestone:
      Component:  Compiler           |                 Version:  7.8.3
       Keywords:                     |        Operating System:
   Architecture:  Unknown/Multiple   |  Unknown/Multiple
     Difficulty:  Unknown            |         Type of failure:
     Blocked By:                     |  None/Unknown
Related Tickets:                     |               Test Case:
                                     |                Blocking:
                                     |  Differential Revisions:
-------------------------------------+-------------------------------------
 ./validate --slow fails thusly:

 {{{
 Unexpected failures:
    ghc-api  T8628 [bad stderr] (normal)

 # run by hands:
 $ LANG=C make fulltest stage=2 TEST=T8628

 =====> T8628(normal) 3453 of 4083 [0, 0, 0]
 cd ./ghc-api && $MAKE -s --no-print-directory T8628    </dev/null
 >T8628.run.stdout 2>T8628.run.stderr
 Actual stderr output differs from expected:
 --- /dev/null   2014-06-09 18:31:31.993762230 +0300
 +++ ./ghc-api/T8628.run.stderr  2014-08-08 16:02:17.000000000 +0300
 @@ -0,0 +1,2 @@
 +WARNING: file compiler/simplCore/SimplEnv.lhs, line 539 $fShowX
 +WARNING: file compiler/simplCore/SimplEnv.lhs, line 539 $fShowX
 *** unexpected failure for T8628(normal)

 }}}

 '''compiler/simplCore/SimplEnv.lhs:539'''
 {{{#!hs
 refine :: InScopeSet -> Var -> Var
 refine in_scope v
   | isLocalId v = case lookupInScope in_scope v of
                   Just v' -> v'
 {- 539 -}         Nothing -> WARN( True, ppr v ) v  -- This is an error!
   | otherwise = v
 }}}

 Is it really a bug as comment suggests?

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9424>
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