[MacPorts] #69719: draco @1.5.7: error: no type named 'invoke_result' in namespace 'std'

[MacPorts]

#69719: draco @1.5.7: error: no type named 'invoke_result' in namespace 'std'
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  Reporter:  Nicob73  |      Owner:  nilason
      Type:  defect   |     Status:  assigned
  Priority:  Normal   |  Milestone:
 Component:  ports    |    Version:  2.9.3
Resolution:           |   Keywords:  highsierra
      Port:  draco    |
----------------------+------------------------

Comment (by Nicob73):

 I install 10.13.6 and all the security updates.

 How can I specify C++14 for building this port ?

 Best regards

 Nicolas.

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Ticket URL: <https://trac.macports.org/ticket/69719#comment:2>
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