project(unitybuild_c_and_cxx C CXX) set(srcs "") foreach(s RANGE 1 8) set(src_c "${CMAKE_CURRENT_BINARY_DIR}/s${s}.c") file(WRITE "${src_c}" "int s${s}(void) { return 0; }\n") set(src_cxx "${CMAKE_CURRENT_BINARY_DIR}/s${s}.cxx") file(WRITE "${src_cxx}" "int s${s}(void) { return 0; }\n") list(APPEND srcs "${src_c}") list(APPEND srcs "${src_cxx}") endforeach() add_library(tgt SHARED ${srcs}) set_target_properties(tgt PROPERTIES UNITY_BUILD ON)