title: The meaning of _root_ in sbt
body: <p>I have two separate Scala projects. In both projects, the <code>build.sbt</code> has the line:</p>
  
  <pre><code>lazy val V = _root_.scalafix.sbt.BuildInfo
  </code></pre>
  
  <p>The two projects  contain several projects so both <code>build.sbt</code> files are multi-project builds. In my research, I came across the idea of a root project and I think <code>_root_</code> in the above value denotes the root project.</p>
  
  <p>My problem is that in one of the projects, sbt cannot resolve the symbol <code>scalafix</code> in <code>lazy val V = _root_.scalafix.sbt.BuildInfo</code>. When I search <code>scalafix.sbt.BuildInfo</code> in this project, I can find the related jar but sbt somehow misses it. The two projects in so far as I can tell are almost identical but one resolves <code>scalafix</code> while the other does not.</p>
  
  <p>For both projects, the jar seems to be located at the below directory in my Mac:</p>
  
  <pre><code>/Users/soft/.ivy2/cache/scala_2.12/sbt_1.0/ch.epfl.scala/sbt-scalafix/jars/sbt-scalafix-0.6.0-M19.jar!/scalafix/sbt
  </code></pre>
  
  <p>What is <code>_root_</code> and how can I help sbt resolve <code>scalafix</code>?</p>