[GHC] #9390: Inlining prevents evaluation of ignored parts of unboxed tuples

[GHC]

#9390: Inlining prevents evaluation of ignored parts of unboxed tuples
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              Reporter:  snoyberg    |            Owner:
                  Type:  bug         |           Status:  merge
              Priority:  normal      |        Milestone:  7.8.4
             Component:  Compiler    |          Version:  7.8.3
            Resolution:              |         Keywords:
      Operating System:  Linux       |     Architecture:  x86_64 (amd64)
       Type of failure:  Incorrect   |       Difficulty:  Unknown
  result at runtime                  |       Blocked By:
             Test Case:              |  Related Tickets:
  simplCore/should_run/T9390         |
              Blocking:              |
Differential Revisions:              |
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Comment (by snoyberg):

 OK, I've put together a draft of a document explaining what we've
 discussed in this ticket:

 https://www.fpcomplete.com/tutorial-preview/4431/z0KpB0ai2R

 Comments (and especially corrections) highly welcome!

 There's one thing in particular I wasn't sure of: why is `lazy` necessary
 in the definition of `unsafeDupablePerformIO`?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9390#comment:21>
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