Jed Brown <[email protected]> writes:

Pavan Balaji <[email protected]> writes:

...

This attribute is tested in configure before it’s added to mpi.h.in.

Yes, the configure test is incorrect and the resulting usage in MPICH is broken (does not do what you intend).

As far as I know, #pragma weak MPI_Xyz = PMPI_Xyz is equivalent to what was intended with the attribute syntax __attribute__((weak, alias("PMPI_Xyz"))) (which belongs in an implementation file, not in the public header). Is there a reason to bother testing for the attribute syntax?