ghost_communicator example fails

[mscroggs]

If I run this example:

cargo mpirun --example ghost_communicator --release -n 2 --features "mpi"

I get the error:

thread 'main' panicked at 'assertion failed: `(left != right)`
  left: `0`,
 right: `0`: Index 1 already exists on rank 0.', /rlst/sparse/src/ghost_communicator.rs:38:13

[jedbrown]

Huh, I see this, and it seems like MPI_UNWEIGHTED is not bound in mpi-sys and Topology::Graph is unimplemented. Did you add it in a branch?

error[E0425]: cannot find value `MPI_UNWEIGHTED` in crate `mpi_sys`
   --> sparse/src/ghost_communicator.rs:108:26
    |
108 |                 mpi_sys::MPI_UNWEIGHTED,
    |                          ^^^^^^^^^^^^^^ not found in `mpi_sys`

error[E0425]: cannot find value `MPI_UNWEIGHTED` in crate `mpi_sys`
   --> sparse/src/ghost_communicator.rs:111:26
    |
111 |                 mpi_sys::MPI_UNWEIGHTED,
    |                          ^^^^^^^^^^^^^^ not found in `mpi_sys`

[mscroggs]

Huh, I see this, and it seems like MPI_UNWEIGHTED is not bound in mpi-sys and Topology::Graph is unimplemented. Did you add it in a branch?

error[E0425]: cannot find value `MPI_UNWEIGHTED` in crate `mpi_sys`
   --> sparse/src/ghost_communicator.rs:108:26
    |
108 |                 mpi_sys::MPI_UNWEIGHTED,
    |                          ^^^^^^^^^^^^^^ not found in `mpi_sys`

error[E0425]: cannot find value `MPI_UNWEIGHTED` in crate `mpi_sys`
   --> sparse/src/ghost_communicator.rs:111:26
    |
111 |                 mpi_sys::MPI_UNWEIGHTED,
    |                          ^^^^^^^^^^^^^^ not found in `mpi_sys`

I'm seeing the MPI_UNWEIGHTED ERROR only when using openmpi. With mpich, I get this fail instead.

I've opened #20 for the MPI_UNWEIGHTED error