[GHC] #14282: tagToEnum# . dataToTag# not optimized away

[GHC]

#14282: tagToEnum# . dataToTag# not optimized away
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        Reporter:  dfeuer            |                Owner:  dfeuer
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Compiler          |              Version:  8.2.1
      Resolution:                    |             Keywords:  datacon-tags
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by dfeuer):

 I'm trying, but I've hit a snag. Desugaring (even before optimization)
 produces

 {{{
 bar :: Bool -> Bool
 [LclIdX]
 bar
   = \ (x_aHq :: Bool) ->
       case dataToTag# @ Bool x_aHq of wild_00 { __DEFAULT ->
       tagToEnum# @ Bool wild_00
       }
 end Rec }
 }}}

 so looking for the application directly doesn't work. Is there a way to
 look through the unfolding of `wild_00` to see the `dataToTag#`?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14282#comment:2>
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