You have an old 12-STABLE.but v6.0.1 on 12-STABLE which seems a tad odd.
Code:
dice@molly:~ % uname -a
FreeBSD molly.dicelan.home 12.0-STABLE FreeBSD 12.0-STABLE r350537 MOLLY amd64
dice@molly:~ % clang --version
FreeBSD clang version 8.0.1 (tags/RELEASE_801/final 366581) (based on LLVM 8.0.1)
Target: x86_64-unknown-freebsd12.0
Thread model: posix
InstalledDir: /usr/bin
dice@molly:~ %
Not sure when it was updated, it was a few weeks ago I think.