if (NOT EXISTS "${CMAKE_SOURCE_DIR}/osm2pgsql/CMakeLists.txt")
message(FATAL_ERROR "The osm2pgsql directory is empty.\
Did you forget to check out Nominatim recursively?\
if (NOT EXISTS "${CMAKE_SOURCE_DIR}/osm2pgsql/CMakeLists.txt")
message(FATAL_ERROR "The osm2pgsql directory is empty.\
Did you forget to check out Nominatim recursively?\