execute_process(COMMAND cmake ${CMAKE_BINARY_DIR} RESULT_VARIABLE ret)
if(NOT ret EQUAL 0)
    message(FATAL_ERROR "can't regen")
endif()
execute_process(COMMAND cmake --build ${CMAKE_BINARY_DIR} --target tarball-real2)
if(NOT ret EQUAL 0)
    message(FATAL_ERROR "can't make tarball")
endif()