[Dune] RemoteIndices with nonconforming ALUGrid

[Simon Praetorius]

Hi community,

I'm trying to implement and test the ParallelIndexSet and RemoteIndices
from dune-common with ALUGrid (dim=2/3, elType=simplex/cube,
refineType=nonconforming!)

Therefore, I build up a parallelIndexSet for Vertex DOFs (identified by
its global entity ID) and then I create the RemoteIndices with the
ParallelIndexSet as source and target.

My expectation is the following: When I count the number of non-owner
DOFs it should be equal to the number of remote DOFs with myAttribute !=
owner && remoteAttribute == owner, that is, for each local non-owner DOF
there is exactly one remote owner DOF in the RemoteIndices set. An
owner-DOF is defined as a DOF on an interior entity or on an
overlap/border entity for the process with the highest rank.

Is this assumption correct, also for the case that I have nonconforming
refinement in ALUGrid?

The test passes for YaspGrid, UGGrid, and conforming ALUGrid (simplex
and cube) for grids created using a StructuredGridFactory. (should be
conforming by construction)

I have setup a minimal test-project on

> https://gitlab.mn.tu-dresden.de/spraetor/remoteindices_error

The code is compiled with

1.) dune release/2.6, GCC 8.2, OpenMPI 3.1.3,
2.) dune-git, GCC 7.3, OpenMPI 3.1.1

run with 3 cores, e.g.

> mpirun -np 3 ./build-cmake/src/ParallelIndexSetTest_2 # ERROR
> mpirun -np 3 ./build-cmake/src/ParallelIndexSetTest_4 # ERROR
> mpirun -np 3 ./build-cmake/src/ParallelIndexSetTest_5 # NO-ERROR

Is my assumption wrong, or do I need to consider something special for
nonconforming ALUGrid?

Best,
Simon