Pavan Balaji <[email protected]> writes:

FWIW, even if MPI_VERSION and MPI_SUBVERSION are set correctly, there’s no guarantee that these types are available. Types are only defined based on what compiler you use. For example, if you use a C89 only compiler, these types will not be available.

Though with MPICH, that is decided at configure time. If you later add -std=c89, the header does not avoid defining the types. Note that some applications need to build different modules with different language standards.

configure is the only reliable check for these.

That's what we have always done, but it ends up being quite a lot of configure tests and some people complain because configure takes 100x longer on a multi-million dollar file system than it takes on a laptop, so I was double-checking that they were all necessary.