Bug#1107589: libopenmpi-dev: Support a cross-compatible way of discovering MPI support for C++

[Samuel Thibault]

Hello,

Helmut Grohne, le mar. 10 juin 2025 07:17:33 +0200, a ecrit:
> The CMake code strongly prefers using the compiler wrappers mpicc and
> others.

Yes, since that's the way everybody compiles MPI code.

> So at present, we're in a situation where CMake + MPI + C++ + cross
> compilation does not work in any way. It works if you don't cross build
> (via mpicxx) or if you don't use C++ (via mpi-c.pc).

I don't think anybody really uses mpi-c.pc :) Normally one uses mpicc.

> What is the proper way to discover MPI support for C++?

The usual way is calling mpicxx

Some programs would provide a --with-mpicxx= configure option to specify
another one to use, but there is no real standard.

Samuel