Note: here is a list of minimum compiler versions for Kokkos 4.0: kokkos/kokkos#5285 (comment)

Kokkos regression tests passed. Need to check performance.

Any progress here? Fedora Rawhide has updated kokkos to 4.0 and now the lammps builds are failing. A new release would be very helpful. Thanks.

@opoplawski I think #3701 will address the issue you are seeing, can you confirm?

@akohlmey it looks like the run test failure is unrelated to this PR?

Since this PR requires c++17, we are planning to wait until after the next stable release to merge this, to maximize backwards compatibility. Deprecated code was removed in #3701, which should allow LAMMPS to be compatible with an external Kokkos v4.0.

@akohlmey it looks like the run test failure is unrelated to this PR?

That is correct. It is a ripple from the removal of installing the python module from "make install". The run and regression tests depend on it, and the replacement has a race condition when running "make install-python" concurrently from the same source checkout. It took me a while to narrow down where the exact issue is since there were multiple problems that needed changes in multiple places.

FWIW Stan, I still see a bunch of hash map errors:

lammps/src/KOKKOS/neigh_bond_kokkos.cpp:284:89: error: reference to __host__ function 'dual_hash_type' in __host__ __device__ function
    int atom1 = AtomKokkos::map_kokkos<DeviceType>(bond_atom(i,m),map_style,k_map_array,k_map_hash);
                                                                                        ^
lammps/src/KOKKOS/neigh_bond_kokkos.cpp:1230:16: note: in instantiation of member function 'LAMMPS_NS::NeighBondKokkos<Kokkos::HIP>::operator()' requested here
template class NeighBondKokkos<LMPDeviceType>;
               ^
lammps/src/KOKKOS/kokkos_type.h:511:8: note: 'dual_hash_type' declared here
struct dual_hash_type {
       ^
lammps/src/KOKKOS/neigh_bond_kokkos.cpp:372:89: error: reference to __host__ function 'dual_hash_type' in __host__ __device__ function
    int atom1 = AtomKokkos::map_kokkos<DeviceType>(bond_atom(i,m),map_style,k_map_array,k_map_hash);

when building w/ your branch + Kokkos develop. I think it's because there's still an implicit constructor in the dual_hash_type:

that isn't deleted (and therefore defaults to __host__)?

This might be something specific to develop however.

@stanmoore1 created stanmoore1#16 with some cleanups and a HIP bugfix, which would merge into this PR branch.

Can confirm, this builds w/ the latest kokkos develop on MI-2XX

@akohlmey would like to get this merged ASAP now that the stable is out.

@akohlmey would like to get this merged ASAP now that the stable is out.

Yup. I am working through the back log right now.