[MacPorts] #65532: isl @0.25: builds failing for 10.7 and 10.13; needs fixes for c++17 detection (was: isl @0.25: builds failing for 10.13: call to unavailable member function 'value')

[MacPorts]

#65532: isl @0.25: builds failing for 10.7 and 10.13; needs fixes for c++17
detection
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  Reporter:  dyne2meter  |      Owner:  mascguy
      Type:  defect      |     Status:  assigned
  Priority:  Normal      |  Milestone:
 Component:  ports       |    Version:  2.7.2
Resolution:              |   Keywords:
      Port:  isl         |
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Ticket URL: <https://trac.macports.org/ticket/65532#comment:12>
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