[MacPorts] #68902: inconsistent use of c++ library for mpich with gcc10>

[MacPorts]

#68902: inconsistent use of c++ library for mpich with gcc10>
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 Reporter:  numaryu   |      Owner:  (none)
     Type:  defect    |     Status:  new
 Priority:  Normal    |  Milestone:
Component:  base      |    Version:
 Keywords:  haspatch  |       Port:
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 The correct stdlib option is not passed to mpi C++ (mpicxx) when the
 backend is gcc version greater than 10.
 This causes a compilation error for ports with +mpich +gcc1?, such as
 hdf5, netcdf, etc.
 The attached patches may resolve the issue, but are tested only on my
 environment (MacOS 12.7.1, gcc12, mpich).

 And, I'd also like to point out that the descriptions of stdlib for GCC is
 not correct in the following documents:
 https://trac.macports.org/wiki/UsingTheRightCompiler
 https://trac.macports.org/wiki/CompilerSelection

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Ticket URL: <https://trac.macports.org/ticket/68902>
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