Need to add a dep for the generated header file to the dependency() so that it gets generated before anyone tries to #include files from it (which may happen before the actual lib is built because that's only needed when stuff is linked together later). See https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/2057#note_1323236 and CI build failures in https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/2096 Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/2103>