It&#x27;s half a lint. It collects metadata about the code, making it easier to do whole-program analysis. Most of the lints we have so far do at most whole-function analysis. The other half, to be written, would use the metadata to lint things. &quot;Can never panic&quot; is one such lint that could be written with this for example.<p>As an optimization pass it would have to actually change the generated code. It doesn&#x27;t affect that (nor does Rust&#x27;s plugin lint functionality; which it uses; let you do that)