[MacPorts] #64660: inkscape: build failure due to "no template named 'optional' in namespace 'std'"

[MacPorts]

#64660: inkscape: build failure due to "no template named 'optional' in namespace
'std'"
-------------------------+----------------------
  Reporter:  dyne2meter  |      Owner:  mascguy
      Type:  defect      |     Status:  assigned
  Priority:  Normal      |  Milestone:
 Component:  ports       |    Version:  2.7.1
Resolution:              |   Keywords:
      Port:  inkscape    |
-------------------------+----------------------

Comment (by JDLH):

 I am seeing this on macOS 10.14.6 Mojave, with clang 11.0.0 and MacOS
 10.15 SDK:

 {{{
 % /usr/bin/clang++ --version
 Apple clang version 11.0.0 (clang-1100.0.33.12)
 Target: x86_64-apple-darwin18.7.0
 Thread model: posix
 InstalledDir:
 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
 % ls -F
 /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs
 DriverKit19.0.sdk/      MacOSX.sdk/             MacOSX10.15.sdk@
 }}}

-- 
Ticket URL: <https://trac.macports.org/ticket/64660#comment:5>
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