About the only Unix variant that does anything resembling /usr/src these days is FreeBSD (and related) and it's in /usr/ports/<category>/<project>... /Usr/src

About the only Unix variant that does anything resembling /usr/src these days is FreeBSD (and related) and it's in /usr/ports/<category>/<project>... /Usr/src within the Linux community hasn't really been a normal thing for many many years. Go certainly has old hands involved and the /usr/src example makes sense, but the context is one requiring years of knowledge.