[MacPorts] #70207: c-ares @1.30.0_0: fatal error: 'os/availability.h' file not found

[MacPorts]

#70207: c-ares @1.30.0_0: fatal error: 'os/availability.h' file not found
-------------------------+-------------------------------------------------
  Reporter:              |      Owner:  tobypeterson
  sambthompson           |
      Type:  defect      |     Status:  assigned
  Priority:  Normal      |  Milestone:
 Component:  ports       |    Version:  2.9.3
Resolution:              |   Keywords:  mountainlion mavericks yosemite
      Port:  c-ares      |  elcapitan
-------------------------+-------------------------------------------------

Comment (by sambthompson):

 Replying to [comment:4 ryandesign]:
 > The reason c-ares checks for macOS 10.12 or later appears to be because
 that's when `clock_gettime` was introduced. It looks like it uses the
 check to skip some `clock_gettime` functionality on older systems.
 Thanks for looking into this, and reporting the errors for the earlier OS
 X versions upstream.

 > The correct place to report software bugs is to the software's
 developers. If the developers fix it, we can backport their fix. If they
 refuse to fix it, then we can attempt our own patch.
 Not sure if unsupported versions not compiling would be considered a bug,
 or whether bugs would be accepted for versions considered unsupported.
 However, I was not able to find any clear declaration from c-ares that Mac
 OS X < 10.12 is not supported, so have filed
 https://github.com/c-ares/c-ares/issues/783 for this problem. Hopefully
 they'd be willing to adopt the tweak needed for `clock_gettime` support if
 that's the obstacle, so all Mac users of c-ares get the benefit, and not
 just MacPorts (if they decline and the patch has to be in MacPorts).

-- 
Ticket URL: <https://trac.macports.org/ticket/70207#comment:6>
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