[GHC] #14361: GHC HEAD miscompiles `text-containers`

[GHC]

#14361: GHC HEAD miscompiles `text-containers`
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        Reporter:  hvr               |                Owner:  (none)
            Type:  bug               |               Status:  patch
        Priority:  high              |            Milestone:  8.4.1
       Component:  Compiler          |              Version:  8.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect result  |  Unknown/Multiple
  at runtime                         |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 > It seems like it would be better to either only pass the constructor and
 extract the needed values out of it inside the join point, or to only pass
 the unboxed arguments, and construct the constructor when needed.

 It's indeed not clear which is best.  It's a conscious choice though; see
 `Note [Case binders and join points]` in `Simplify.hs`.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14361#comment:14>
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