[GHC] #10176: Invalid core generated with GHC 7.10 RC3

[GHC]

#10176: Invalid core generated with GHC 7.10 RC3
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        Reporter:  NeilMitchell      |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  high              |               Milestone:  7.10.1
       Component:  Compiler          |                 Version:  7.10.1-rc3
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  None/Unknown      |  Unknown/Multiple
      Blocked By:                    |               Test Case:
 Related Tickets:                    |                Blocking:
                                     |  Differential Revisions:
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Comment (by nomeata):

 Or not quite. I think I did find a bug, but not the only one: With the
 change in Phab:D747, my small example and your example, when merged into
 one module, no longer fail. But your original test case still fails with
 Call Arity, and compiles fine without.

 There still seems to be some fishiness with Call Arity and `undefined`.
 /me continues brooding over the Core.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10176#comment:11>
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