[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:
            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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Comment (by rwbarton):

 What about `seq#` and `seq`? I'm not sure what it means for `seq` to be a
 "pseudoop", but `seq#` is a primop that takes a lifted argument and as far
 as I know it does evaluate that argument. Does it need `can_fail` too
 then?

 If there's a new invariant that primops that take lifted arguments must
 either not examine them or have some flag(s) set (such as `can_fail`), a
 reference to `Note [Primops with lifted arguments]` at the top of
 primops.pp would be nice.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13027#comment:30>
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