Hello. I am also a little concerned about this issue. I have made it so that doxygen is installed with the DOCS option in multimedia/libopenshot and audio/libopenshot-audio, which I maintain. Perhaps one positive answer is the way astro/geographiclib, which I maintain :), does things. It relates as DOXYGEN_IMPLIES=DOCS. Such a way would be limited to cases where there is a way to switch the behavior depending on the presence or absence of doxygen.
This is probably why we don't want to use doxygen for our builds. https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=259331 I have sent one email upstream regarding this and received no response :) Currently not yet fixed. And since another fix (s/PYTHON/Python/) was made in that nearby area, the patch cannot be applied directly either. Regards.
