[GHC] #10176: Invalid core generated with GHC 7.10 RC3

[GHC]

#10176: Invalid core generated with GHC 7.10 RC3
-------------------------------------+-------------------------------------
        Reporter:  NeilMitchell      |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  high              |               Milestone:  7.10.1
       Component:  Compiler          |                 Version:  7.10.1-rc3
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  None/Unknown      |  Unknown/Multiple
      Blocked By:                    |               Test Case:
 Related Tickets:                    |                Blocking:
                                     |  Differential Revisions:
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Comment (by NeilMitchell):

 That's quite different since (after inlining a few bits):

 {{{
 $wlvl
 $wlvl = \ _ -> error "here"

 m = $wlvl void#
 }}}

 So {{{m}}} evaluates to {{{_|_}}} in GHC 7.8 which means a case with no
 alternatives is correct. However, in 7.10 the scrutinee evaluates to a
 lambda, not {{{_|_}}}, so no alternatives is wrong.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10176#comment:5>
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