Compiling libsc with openMPI using CMake fails to find MPI_COMM_TYPE_SHARED

[maelk3]

Description
Compiling libsc with openMPI using the CMake build system does not find MPI_COMM_TYPE_SHARED. Down the line, on t8code, this causes issues DLR-AMR/t8code#1109 with shared memory usage.

To Reproduce

cmake ..  -Dmpi=ON

Additional information
The issue stems from the fact that MPI_COMM_TYPE_SHARED is defined as part of an anonymous enum on openMPI's mpi.h header file (instead of a macro definition), and the CMake function check_symbol_exists only checks for macro definition. A easy solution would be to use check_c_source_compiles instead. I would be glad to provide a pull request if this issue is considered.

[cburstedde]

Thanks for the report!

We had this type of error before on a different matter. @tim-griesbach, do you see a solution to this issue?

[tim-griesbach]

We had this type of error before on a different matter. @tim-griesbach, do you see a solution to this issue?

I think that @maelk3's proposal of creating a PR to use check_c_source_compiles instead of check_symbol_exists is a good solution. It is also aligned with the recommendation of the CMake documentation for checking enums.

[cburstedde]

Please go for it @maelk3. This will be good to fix! Compile-link-checking is sensible for all MPI functionalities that presently use symbol_exists, as well as for qsort_r: The latter has two different conventions flying around, one from BSD and one GNU. Please see the autoconf code in config/sc_qsort.m4 in case you like to address the latter as well.

[cburstedde]

This has been addressed quickly thanks to @maelk3. :)