The talkd protocol defined in include/protocols/talkd.h uses the struct osockaddr definition from sys/socket.h. It should define it's own type so struct osockaddr can be removed from non-kernel use. The support for systems where sockaddr is the same as osockaddr in the talk program should also be removed since we don't need our tools to run on 4.3BSD.
https://reviews.freebsd.org/D14505 contains a fix.
A commit references this bug: Author: brooks Date: Fri Jan 18 21:30:07 UTC 2019 New revision: 343161 URL: https://svnweb.freebsd.org/changeset/base/343161 Log: Use a private definition of osockaddr rather then relying on type namespace polution in sys/socket.h. Also remove support for operation on 4.3BSD. PR: 224529 Differential Revision: https://reviews.freebsd.org/D14505 Changes: head/include/protocols/talkd.h head/libexec/talkd/talkd.c head/usr.bin/talk/invite.c head/usr.bin/talk/look_up.c
No sense in MFCing this no-op change.