forward Kokkos library variables from CMake configuration for LAMMPS to the...

option(EXTERNAL_KOKKOS "Build against external kokkos library" OFF)

option(DOWNLOAD_KOKKOS "Download the KOKKOS library instead of using the bundled one" OFF)

if(DOWNLOAD_KOKKOS)

  # extract Kokkos-related variables and values so we can forward them to the Kokkos library build

  get_cmake_property(_VARS VARIABLES)

  list(FILTER _VARS INCLUDE REGEX ^Kokkos_)

  foreach(_VAR IN LISTS _VARS)

    list(APPEND KOKKOS_LIB_BUILD_ARGS "-D${_VAR}=${${_VAR}}")

  endforeach()

  message(STATUS "KOKKOS download requested - we will build our own")

  list(APPEND KOKKOS_LIB_BUILD_ARGS "-DCMAKE_INSTALL_PREFIX=<INSTALL_DIR>")

  if(CMAKE_REQUEST_PIC)

    list(APPEND KOKKOS_LIB_BUILD_ARGS ${CMAKE_REQUEST_PIC})

  endif()

  # append other CMake variables that need to be forwarded to CMAKE_ARGS

  list(APPEND KOKKOS_LIB_BUILD_ARGS "-DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}")

  list(APPEND KOKKOS_LIB_BUILD_ARGS "-DCMAKE_INSTALL_LIBDIR=lib")

  list(APPEND KOKKOS_LIB_BUILD_ARGS "-DCMAKE_MAKE_PROGRAM=${CMAKE_MAKE_PROGRAM}")

  list(APPEND KOKKOS_LIB_BUILD_ARGS "-DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}")

  list(APPEND KOKKOS_LIB_BUILD_ARGS "-DCMAKE_CXX_STANDARD=${CMAKE_CXX_STANDARD}")

  list(APPEND KOKKOS_LIB_BUILD_ARGS "-DCMAKE_CXX_EXTENSIONS=${CMAKE_CXX_EXTENSIONS}")

  list(APPEND KOKKOS_LIB_BUILD_ARGS "-DCMAKE_TOOLCHAIN_FILE=${CMAKE_TOOLCHAIN_FILE}")

  include(ExternalProject)

  ExternalProject_Add(kokkos_build

    URL https://github.com/kokkos/kokkos/archive/3.1.00.tar.gz

    URL_MD5 f638a6c786f748a602b26faa0e96ebab

    CMAKE_ARGS -DCMAKE_INSTALL_PREFIX=<INSTALL_DIR> ${CMAKE_REQUEST_PIC}

    -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE} -DCMAKE_INSTALL_LIBDIR=lib

    -DCMAKE_MAKE_PROGRAM=${CMAKE_MAKE_PROGRAM} -DCMAKE_TOOLCHAIN_FILE=${CMAKE_TOOLCHAIN_FILE}

    CMAKE_ARGS ${KOKKOS_LIB_BUILD_ARGS}

    BUILD_BYPRODUCTS <INSTALL_DIR>/lib/libkokkoscore.a

  )

  ExternalProject_get_property(kokkos_build INSTALL_DIR)