enable_language(CXX) add_custom_command(OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/copied_file.cpp" COMMAND "${CMAKE_COMMAND}" -E copy "${CMAKE_CURRENT_SOURCE_DIR}/empty.cpp" "${CMAKE_CURRENT_BINARY_DIR}/copied_file$<TARGET_POLICY:CMP0004>.cpp" ) add_library(empty "${CMAKE_CURRENT_BINARY_DIR}/copied_file.cpp")