Module mpi3

      implicit none

      include "mpif.h"

! Exemplary derived type for a communicator

      Type MPI_Comm
         Private
         Type (C_ptr) :: MPIR_comm_ptr
         Integer :: Other_process_dependent_mpi_data
         Integer :: More_process_dependent_mpi_data
      End Type MPI_Comm

      End Module mpi3

      program bcast_derived_type
      use mpi3

      Implicit none

! Derived User type containing a communicator

      Type My_type
          Integer                   :: my_int
          Integer, Pointer          :: pointer1
          Double Precision, Pointer :: pointer2

          Type (MPI_Comm)           :: my_comm
      End Type My_type

      Type (My_type) :: var1
      Integer :: ierror, len


      call MPI_Init (ierror)

      call MPI_Comm_dup (MPI_COMM_WORLD, var1%my_comm, ierror)

! Some time later; overloaded by several interface descriptions
! a MPI_Bcast is executed for "var1"
! This will overwrite the data of "var1" in the non-root processes
!
! I know that this is not portable and that this is not intened by MPI.
! But I have seen such usage of derived types in application programs.
! Application programmers use this byte stream since it's
! too "difficult" to set up a derived MPI datatype for large
! Fortran derived tyes and since this works on "all" (they claim) systems.

!     Get size (in bytes) of derived type "my_type"
!     Size includes size of type MPI_Comm
      len = size (transfer (var1, (/' '/)))

      call MPI_Bcast (var1, len, MPI_BYTE, 0, MPI_COMM_WORLD, ierror)

! After that, the process dependent data of "my_comm" is changed and
! usage of my_comm may result in very strange problems.
!
      call MPI_Finalize (ierror)
      end