[MacPorts] #52335: xorg-libX11 @1.6.3: fails to configure on sierra with Xcode 8.0

[MacPorts]

#52335: xorg-libX11 @1.6.3: fails to configure on sierra with Xcode 8.0
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  Reporter:  Julian.Byrne@…  |      Owner:  jeremyhu@…
      Type:  defect          |     Status:  new
  Priority:  Normal          |  Milestone:
 Component:  ports           |    Version:  2.3.4
Resolution:                  |   Keywords:  sierra
      Port:  xorg-libX11     |
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Comment (by Julian.Byrne@…):

 config.log and main.log attached. How do I verify XCode command line tools
 are correct version?

 Possibly relevant:
 * The xorg-libX11 configure script is hardwired to use /usr/bin/cpp, not
 cpp from the PATH.
 * /usr/bin/cpp is now acting as a noop - no error with any argument but no
 processing either. Different from a few days ago (assuming I haven't made
 an error...) when it apparently accepted arguments (eg. -dM) and processed
 as expected. Some system updates and MacPorts installs since then.
 * md5 /usr/bin/cpp -> 34269fdd32c114870b1114dbd6db4f7d .
 * The failure is on a box that has been upgraded from Yosemite to El
 Capitan to Sierra.
 * All current XCode or system software updates applied.
 * Attached hexdump appears to show /usr/bin/cpp is a shim, not the actual
 cpp.
 * xcode-select version 2345.1.
 * xcode-select -p gives /Applications/Xcode.app/Contents/Developer .
 *
 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/cpp
 is a shell script which claims in the comments that cpp is deprecated.
 This script calls xcrun - see ticket #52200.
 * Root can't rename /usr/bin/cpp however I hacked the xorg-libX11
 configure script to use /opt/local/bin/cpp-mp-6 instead and it configured
 & built fine.

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Ticket URL: <https://trac.macports.org/ticket/52335#comment:3>
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