Cannot compile libgeodecomp (libflatarray) incomplete type

[dvalters]

Cmake ran succesfully with -DWITH_MPI=true as an extra flag, gcc version 8.5.0, Centos 8

Running make on the next step however now results in:

libgeodecomp-0.4.0/lib/libflatarray/src/libflatarray/detail/macros.hpp:35:69: error: incomplete type ‘LibFlatArray::detail::flat_array::offset<LibGeoDecomp::TestCell<3, LibGeoDecomp::Stencils::Moore<3, 1>, LibGeoDecomp::TopologiesHelpers::Topology<3, false, false, false>, LibGeoDecomp::TestCellHelpers::SoAAPI>, -1>’ used in nested name specifier
         static const std::size_t OFFSET = offset<CELL_TYPE, r - 2>::OFFSET +  \
                                                                     ^~~~~~

Several pages worth of compiler error follow, but all very similar to this incomplete type error - am I doing something wrong here or missing something?

Thanks again in advance