[GHC] #13805: GHC 8.0.2 fails to build on macOS 10.13/Xcode 9 - preprocessor error in ghc-pkg

[GHC]

#13805: GHC 8.0.2 fails to build on macOS 10.13/Xcode 9 - preprocessor error in
ghc-pkg
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        Reporter:  mistydemeo        |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  ghc-pkg           |              Version:  8.0.2
      Resolution:                    |             Keywords:
Operating System:  MacOS X           |         Architecture:  x86_64
 Type of failure:  Building GHC      |  (amd64)
  failed                             |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by mistydemeo):

 After looking into it, I think the problem is that the editor placeholder
 check is too lax, which I've reported to clang with a patch:
 https://bugs.llvm.org/show_bug.cgi?id=33394 `<#>` doesn't meet the
 requirements because it has only a single hash, but the check matched it
 by accident.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13805#comment:2>
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