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

[GHC]

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

 {{{#!hs
 foo :: Int# -> Int#
 foo x = dataToTag# (tagToEnum# x :: Bool)

 bar :: Bool -> Bool
 bar x = tagToEnum# (dataToTag# x)
 }}}

 These are both effectively identity functions. But while `foo` simplifies
 to one, `bar` does not! We might want to fix that.

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