[MacPorts] #59835: cmake: strange libc++ "if" condition

[MacPorts]

#59835: cmake: strange libc++ "if" condition
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  Reporter:  michaelld  |      Owner:  (none)
      Type:  defect     |     Status:  new
  Priority:  Normal     |  Milestone:
 Component:  ports      |    Version:
Resolution:             |   Keywords:
      Port:  cmake      |
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Comment (by RJVB):

 Replying to [comment:10 kencu]:
 > I would wrap this whole bit  in a pkatform darwin block to simplify, but
 I see the issue with that now...

 Apart from `pkatform` raising a syntax error 8-) what would be the issue
 with a properly spelled `platform darwin` block?

 Indeed, my gripe was with the platform test, esp. since combined with
 `$os.major < 10` it will fire on Linux until a hypothetical 11-series
 kernel. Moving the platform test into its own if or equivalent would make
 the statement easier to read and easier to get right.

 Unrelated:
 >  I can't presently build cmake against libstdc++ (our new c++11 version)
 using any compiler on 10.5 Intel.

 What if you build libc++ like it is done on Linux, that is against
 libstdc++? I cannot recall whether I did that using GCC instead of Clang,
 but I think it should be possible. Then, apply my libc++ patch for GCC
 (currently for GCC 7) and you can use `g++-mp-X -stdlib=libc++`. If I had
 been more dedicated to this little project the patch would probably have
 made it into GCC already...
 I assume that dependent code being built against libc++ doesn't see what
 ABI library libc++ uses behind the scenes (libc++ can work with at least
 3).

-- 
Ticket URL: <https://trac.macports.org/ticket/59835#comment:13>
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