[MacPorts] #55382: cmake @3.10.0: Cannot find a C++ compiler supporting C++11 on this system

[MacPorts]

#55382: cmake @3.10.0: Cannot find a C++ compiler supporting C++11 on this system
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  Reporter:  ryandesign  |      Owner:  michaelld
      Type:  defect      |     Status:  new
  Priority:  High        |  Milestone:
 Component:  ports       |    Version:
Resolution:              |   Keywords:  tiger leopard snowleopard lion
      Port:  cmake       |  mountainlion
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Comment (by kencu):

 > So you would like to force 10.8 and earlier to use gcc6 to build cmake?

 No. But 10.4 to 10.8, using the cxx11 1.1 PG, currently get a c++11
 libstdc++ from libgcc. On PPC, gcc6 builds against that. On Intel on older
 systems, clang-5.0 builds against it.

 >I explained above why this seems much more complicated and potentially
 unreliable, unless we have cmake39

 install to a different prefix, such as /opt/local/libexec/cmake39.
 I don't quite understand why you think this. Once cmake39 is installed,
 the cmake dependency is fulfilled.


 So as I see it, there are two choices:
 1. put a peg in the cmake portfile, and see how long it lasts until it
 breaks someday. Easy. Done.
 1. make a cmake39 port, and then figure out how to use it properly. For
 now, using the block I mentioned, serve it up to older systems that don't
 have cmake installed. Older systems that do have cmake installed probably
 also have clang-5.0 installed, and can build cmake 3.10.

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Ticket URL: <https://trac.macports.org/ticket/55382#comment:31>
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