On Wed, 24 Mar 2021, Satish Balay via petsc-dev wrote:

If MS-MPI is missing mpi.mod - I guess we'll have to revert this requirement. For some reason the tests in CI don't error out. I'll have to check.

I can add back mpif.h usage [without the extra complex code we had for handling some corner cases - in this mode]

I have this [yet untested] change in balay/revert-mpi.mod-check Satish