[MacPorts] #57543: root6 build stage fails with Exit code: 2

[MacPorts]

#57543: root6 build stage fails with Exit code: 2
-----------------------+--------------------------
  Reporter:  jfcaron3  |      Owner:  cjones051073
      Type:  defect    |     Status:  assigned
  Priority:  Normal    |  Milestone:
 Component:  ports     |    Version:  2.5.4
Resolution:            |   Keywords:
      Port:  root6     |
-----------------------+--------------------------

Comment (by cjones051073):

 I am aware of the underlying issue

 {{{
 :info:build In file included from /opt/local/include/tbb/tbb.h:81:
 :info:build /opt/local/include/tbb/task_group.h:132:53: error:
 'uncaught_exceptions' is unavailable: introduced in macOS 10.12
 :info:build             bool stack_unwinding_in_progress =
 std::uncaught_exceptions() > 0;
 :info:build                                                     ^
 :info:build /opt/local/libexec/llvm-5.0/include/c++/v1/exception:130:63:
 note: 'uncaught_exceptions' has been explicitly marked unavailable here
 :info:build _LIBCPP_FUNC_VIS _LIBCPP_AVAILABILITY_UNCAUGHT_EXCEPTIONS int
 uncaught_exceptions() _NOEXCEPT;
 :info:build
 ^
 }}}

 I have yet to find a solution to it, other than suggest you update your OS
 to 10.12 or newer.

-- 
Ticket URL: <https://trac.macports.org/ticket/57543#comment:2>
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