[MacPorts] #41321: cmake: invalid deployment target for -stdlib=libc++ (requires OS X 10.7 or later)

[MacPorts]

#41321: cmake: invalid deployment target for -stdlib=libc++ (requires OS X 10.7 or
later)
---------------------------+-----------------------
  Reporter:  ryandesign@…  |      Owner:  css@…
      Type:  defect        |     Status:  new
  Priority:  Normal        |  Milestone:
 Component:  ports         |    Version:  2.2.99
Resolution:                |   Keywords:  mavericks
      Port:  cmake         |
---------------------------+-----------------------

Comment (by ryandesign@…):

 Still not sure why the KDE ports are affected by this issue but other
 ports that use cmake, like graphite2, aren't.

 Based on r78651 I think the only reason why we're not setting the SDK all
 the time is that it was a problem with Tiger's gcc-4.0. So we could just
 special-case Tiger, and use the right SDK on every later OS.

 Where should this be done? It could be in the cmake portgroup if we want
 to replicate the logic from base for finding the SDK based on the Xcode
 version. Or we could make the change in base, thus actually setting
 `${configure.sdkroot}` in most cases, thus actually passing the
 `-isysroot` flag in most cases. This has the potential for causing build
 failures in ports that'd not properly support switching the SDK, but it
 might be a good idea to become aware of and fix those problems.

 We could potentially avoid the special case for Tiger by switching the
 default compiler for Tiger to the apple-gcc42 port; this would also help
 with #40656.

-- 
Ticket URL: <https://trac.macports.org/ticket/41321#comment:10>
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