[MacPorts] #60453: build failure wxMaxima

[MacPorts]

#60453: build failure wxMaxima
-------------------------+--------------------------
  Reporter:  dyne2meter  |      Owner:  MSoegtropIMC
      Type:  defect      |     Status:  assigned
  Priority:  Normal      |  Milestone:
 Component:  ports       |    Version:  2.6.2
Resolution:              |   Keywords:
      Port:  wxMaxima    |
-------------------------+--------------------------

Comment (by michaellass):

 I have /opt/local/bin at the front of $PATH, so the output looks a bit
 different:

 {{{
  ~ % which clang
 /opt/local/bin/clang
  ~ % /opt/local/bin/clang --version
 clang version 9.0.1
 Target: x86_64-apple-darwin19.4.0
 Thread model: posix
 InstalledDir: /opt/local/libexec/llvm-9.0/bin
  ~ % /usr/bin/clang --version
 Apple clang version 11.0.3 (clang-1103.0.32.59)
 Target: x86_64-apple-darwin19.4.0
 Thread model: posix
 InstalledDir:
 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
 }}}

 But I think this misses the point becuase clang is not our issue here. The
 important aspect is that I have gcc9 installed via macports and set as
 default gcc version. I think to reproduce the problem you need to do the
 following:

 1. port install gcc9
 2. port select --set gcc mp-gcc9
 3. make sure that /opt/local/bin is at the front of your $PATH

 I think what is happening then: CMake just chooses c++ from $PATH and this
 happens to be gcc:

 {{{
  ~ % which c++
 /opt/local/bin/c++
  ~ % /opt/local/bin/c++ --version
 c++ (MacPorts gcc9 9.3.0_1) 9.3.0
 Copyright (C) 2019 Free Software Foundation, Inc.
 This is free software; see the source for copying conditions.  There is NO
 warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
 PURPOSE.
 }}}

 It may be questionable to overwrite the default c++, but normally this
 does not cause issues because macports chooses a suitable compiler (clang
 macports-clang-9.0 macports-clang-8.0 ...). The problem in the current
 Portfile is that CMake does not know about that.

-- 
Ticket URL: <https://trac.macports.org/ticket/60453#comment:14>
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