+IF(GRAPHVIZ_EXECUTABLE)
+ EXECUTE_PROCESS(COMMAND ${GRAPHVIZ_EXECUTABLE} "-V" ERROR_VARIABLE GRAPHVIZ_VERSION ERROR_STRIP_TRAILING_WHITESPACE)
+ STRING(REGEX REPLACE ".* ([0-9.]+) .*" "\\1" GRAPHVIZ_VERSION "${GRAPHVIZ_VERSION}")
+ENDIF()
+
+SET(GRAPHVIZ_DEFINITIONS)
+IF("${GRAPHVIZ_VERSION}" VERSION_LESS "2.36.0")
+ SET(GRAPHVIZ_DEFINITIONS -DWITH_CGRAPH)
+ENDIF()
+