Re: meta mode

void:
> But, from time to time, one might be required to make
> cleanworld && make cleandir (to be sure) && make clean (to be *really* sure)
 
> What circumstances & notices in /usr/src/UPDATING would require it?

one case this is required in non-meta mode is if you use pkg(8) (e.g.,
with poudriere), which determines the 'running kernel' version by
looking at the ELF notes of /usr/bin/uname.  if __FreeBSD_version is
bumped but that binary isn't rebuilt, which is normal with an
incremental build then pkg will report a version mismatch error.

the (easiest) fix for that is to do a full rebuild every time
__FreeBSD_version changes.

pkg(8) bug report: https://github.com/freebsd/pkg/issues/2162

i don't know if meta mode will catch this and rebuild correctly, but
since this confused me the first time i ran into it, i thought it was
worth mentioning.