Fortran MPI programs should use the Fortran mpi_f08 interface:

use mpi_f08

Intel MPI supports Fortran mpi_f08 including on Windows using free Intel oneAPI compiler.

MPI constants like mpi_comm_world and mpi_real are Fortran derived types.

For legacy user programs if needed, access the MPI legacy integer value via the %mpi_val property.

use mpi_f08

integer :: comm = mpi_comm_world%mpi_val
!! %mpi_var emits the legacy integer

Fortran MPI examples