[GHC] #13027: The let/app invariant, evaluated-ness, and reallyUnsafePtrEquality#

[GHC]

#13027: The let/app invariant, evaluated-ness, and reallyUnsafePtrEquality#
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        Reporter:  erikd             |                Owner:  dfeuer
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  8.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Building GHC      |            Test Case:
  failed                             |  simplCore/should_compile/T13027
      Blocked By:                    |             Blocking:
 Related Tickets:  #11444            |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by simonpj):

 * cc: simonmar (added)


Comment:

 Yes, but they really do have side effects.  It matters when they are
 executed, and it matters if they are not executed at all.

 That said, I doubt it would matter if the (badly named) `seq#` also had
 these attributes.

 I wish I could think of an obviously-correct way to reason about this,
 rather than simply not being able to see a problem.   Simon Marlow may be
 able to help.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13027#comment:35>
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