What replaces DIOCGDINFO?

-r276737 removed 4 ioctls, including DIOCGDINFO, from <sys/disklabel.h>.
The commit log entry says only "Remove old ioctl use and support, once
and for all."

What are users of that mechanism supposed to use instead?
A grep in UPDATING for either DIOCGDINFO or ioctl came up empty.

BTW I ran into this because it breaks a port I maintain.  I do not
run CURRENT, and thus have not been reading current_at_ -- but a quick
perusal of the current month's archives did not turn up anything
obviously pertinent.