[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:  new
              Priority:  normal      |        Milestone:
             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:
              Blocking:              |
Differential Revisions:              |
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Comment (by simonpj):

 Well this is very interesting.  It turns out that
  * The desugarer was generating Core that did not satisfy the let/app
 invariant (in `CoreSyn`)
  * Core Lint was failing to check that the invariant was satisfied
  * The simplifier, quite reasonably, assumed that the invariant holds, and
 thereby discarded an expression that has side effects.

 Patch coming

 Great bug report, btw.  Thanks!

 Simon

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9390#comment:5>
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