[MacPorts] #44125: cmake: default values of CMAKE_OSX_SYSROOT/DEPLOYMENT_TARGET (prevent linking against libc++)

[MacPorts]

#44125: cmake: default values of CMAKE_OSX_SYSROOT/DEPLOYMENT_TARGET (prevent
linking against libc++)
---------------------------+--------------------------------
  Reporter:  mojca@…       |      Owner:  macports-tickets@…
      Type:  defect        |     Status:  new
  Priority:  Normal        |  Milestone:
 Component:  ports         |    Version:
Resolution:                |   Keywords:
      Port:  cmake libcxx  |
---------------------------+--------------------------------

Comment (by mojca@…):

 See #44062.

 The compilation fails with:
 {{{
 ld: library not found for -lc++
 }}}
 because there is no `libc++` inside `/Developer/SDKs/MacOSX10.6.sdk`. One
 possible solution would be to symlink/copy `libc++` also to the SDK (which
 might include doing the same on Lion in case that the 10.6 SDK is present;
 the SDK for 10.6 could be used for wxWidgets for example, but then again
 wxWidgets doesn't use CMake, so it's not an issue).

 The other solution would be to set
 {{{
 -DCMAKE_OSX_SYSROOT="/" \
 -DCMAKE_OSX_DEPLOYMENT_TARGET=""
 }}}
 by the CMake PortGroup unless explicitly requested otherwise.

-- 
Ticket URL: <https://trac.macports.org/ticket/44125#comment:4>
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