[GHC] #13027: Core lint errors compiling containers HEAD with GHC HEAD

[GHC]

#13027: Core lint errors compiling containers HEAD with GHC HEAD
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        Reporter:  erikd             |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  8.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Building GHC      |  Unknown/Multiple
  failed                             |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by dfeuer):

 Based on my extremely naive reading of the let/app invariant note, I'm
 *guessing* that the simplifier may be doing something weird like

 {{{#!hs
 ptrEq x y = let r = reallyUnsafePtrEquality# x y
             in isTrue# r
 }}}

 when it really should be doing

 {{{#!hs
 ptrEq x y = case reallyUnsafePtrEquality# x y of
               r -> isTrue# r
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13027#comment:2>
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