add -Xsource:3 option

Author: xuwei-k

app/src/main/scala/app.scala

@@ -2,7 +2,7 @@ package pamflet
 import java.io.File
 
 class Pamflet extends xsbti.AppMain {
-  def run(config: xsbti.AppConfiguration) = {
+  def run(config: xsbti.AppConfiguration): xsbti.MainResult = {
     Exit(Pamflet.run(config.arguments))
   }
   case class Exit(val code: Int) extends xsbti.Exit

build.sbt

@@ -27,6 +27,14 @@ ThisBuild / publishTo := sonatypePublishToBundle.value
 
 lazy val common = Seq(
   scalacOptions ++= Seq("-language:_", "-deprecation"),
+  scalacOptions ++= {
+    scalaBinaryVersion.value match {
+      case "3" =>
+        Nil
+      case _ =>
+        Seq("-Xsource:3")
+    }
+  },
   scalacOptions ++= {
     CrossVersion.partialVersion(scalaVersion.value) match {
       case Some((2, v)) if v <= 12 => Seq("-Yno-adapted-args", "-Xfuture")

knockoff/src/main/scala/smarty.scala

@@ -5,7 +5,7 @@ import scala.util.matching.Regex
 
 trait SmartyDiscounter extends Discounter {
   override def createSpanConverter(
-    linkDefinitions: collection.Seq[LinkDefinitionChunk]) =
+    linkDefinitions: collection.Seq[LinkDefinitionChunk]): SpanConverter =
     new SpanConverter(linkDefinitions) with SmartySpanConverter
 }