CountImplicitKeywordPlugin.scala

import sbt.*
import sbt.Keys.*

object CountImplicitKeywordPlugin extends AutoPlugin {
  override def trigger: PluginTrigger = allRequirements
  object autoImport {
    val implicitKeyword    = taskKey[Int]("")
    val allImplicitKeyword = taskKey[Seq[(String, Int)]]("")
  }
  import autoImport.*

  override def globalSettings: Seq[Def.Setting[?]] = Def.settings(
    allImplicitKeyword := Def.taskDyn {
      val s               = state.value
      val extracted       = Project.extract(s)
      val currentBuildUri = extracted.currentRef.build
      val projects = extracted.structure.units
        .apply(currentBuildUri)
        .defined
        .values
        .toList
      Def.task {
        val x1: Seq[(String, Int)] =
          projects.map(_.id).zip(projects.map(p => LocalProject(p.id) / Compile / implicitKeyword).join.value)
        val x2: Seq[(String, Int)] =
          projects.map(_.id).zip(projects.map(p => LocalProject(p.id) / Test / implicitKeyword).join.value)
        val result = x1.map(x => x.copy(_1 = x._1 + "-main")) ++ x2.map(x => x.copy(_1 = x._1 + "-test"))
        val res    = result.sortBy(_._2).filter(_._2 > 0)
        res.foreach(println)
        println("all = " + res.map(_._2).sum)
        res
      }
    }.value
  )
  override def projectSettings: Seq[Def.Setting[?]] = Def.settings(
    Seq(Compile, Test).map { x =>
      (x / implicitKeyword) := {
        import scala.meta.*
        (x / unmanagedSources).value.map { file =>
          val input = Input.File(file)
          val tree  = implicitly[parsers.Parse[Source]].apply(input, dialects.Scala3).get
          tree.tokens
            .collect {
              case c: Token.KwImplicit => (c.pos.start, c.pos.end)
            }.distinct.size
        }.sum
      }
    }
  )
}

plugins.sbt

libraryDependencies += "org.scalameta" %% "scalameta" % "4.11.1"