After trying to retrieve scaladoc for 'millis', the compiler will show a spurious error:

package foo

import scala.concurrent.duration._

object Foo {
  val xs = 3.millis
}

It does not happen after hyperlinking, so it seems that whatever computation is performed during doc comment retrieval is at fault.

The implicit is defined in a universalt trait, mixed-in in an implicit value class defined inside a package object. Any of these might contribute to the error. Couldn't yet reproduce this in a similar, self-contained project.