To be clear, this isn't "intelligent" search. There is no magic here. It's just fast, advanced code search across multiple repositories (like what Google and Facebook offer their devs internally). This means support for regular expressions, always getting extremely up-to-date results, etc. You can read more about it here: https://about.sourcegraph.com/docs/search
There is "code intelligence", which is a phrase we use to describe IDE-like features such as jump-to-definition, find-references, etc.