Add Scala 3 support

build.sbt

@@ -3,12 +3,14 @@ import scoverage._
 import xerial.sbt.Sonatype._
 
 def scala213 = Def.setting(scalaVersion.value.startsWith("2.13"))
+def scala3 = Def.setting(scalaVersion.value.startsWith("3."))
+
 lazy val crossVersionSourcesSettings =
   Seq(Compile, Test).map { sc =>
     (sc / unmanagedSourceDirectories) ++= {
       (sc / unmanagedSourceDirectories).value.flatMap { dir =>
         if (dir.getPath.endsWith("scala"))
-          Seq(new File(dir.getPath + (if (scala213.value) "_2.13+" else "_2.13-")))
+          Seq(new File(dir.getPath + (if (scala213.value || scala3.value) "_2.13+" else "_2.13-")))
         else
           Seq.empty
       }
@@ -54,41 +56,51 @@ val publishSettings = sonatypeSettings ++ Seq(
 val commonSettings = Seq(
   organization := "com.daodecode",
   scalaVersion := "2.13.11",
-  crossScalaVersions := Seq(scalaVersion.value, "2.12.18"),
+  crossScalaVersions := Seq(scalaVersion.value, "2.12.18", "3.3.0"),
   scalafmtConfig := Some(scalaj.base / "scalafmt-config/.scalafmt.conf")
 ) ++ releaseSettings ++ crossVersionSourcesSettings
 
+val Scala212ScalacOptions = Seq(
+  "-Xlint",
+  "-unchecked",
+  "-deprecation",
+  "-Xfatal-warnings",
+  "-Ywarn-inaccessible",
+  "-Ywarn-dead-code",
+  "-Ywarn-adapted-args",
+  "-Ywarn-nullary-unit",
+  "-feature",
+  "-Ywarn-unused",
+  "-Ywarn-unused-import",
+  "-encoding", "UTF-8"
+)
+
+val Scala213ScalacOptions = Seq(
+  "-Xlint",
+  "-unchecked",
+  "-deprecation",
+  "-Xfatal-warnings",
+  "-Ywarn-dead-code",
+  "-feature",
+  "-Ywarn-unused",
+  "-encoding", "UTF-8",
+  "-Wconf:origin=scala.collection.compat.*:s"
+)
+
+val Scala3ScalacOptions = Seq(
+  "-unchecked",
+  "-deprecation",
+  "-Werror",
+  "-feature",
+  "-encoding", "UTF-8"
+)
+
 val moduleSettings = commonSettings ++ Seq(
-  scalacOptions :=
-    (if (scala213.value)
-       Seq(
-         "-Xlint",
-         "-unchecked",
-         "-deprecation",
-         "-Xfatal-warnings",
-         "-Ywarn-dead-code",
-         "-feature",
-         "-Ywarn-unused",
-         "-encoding",
-         "UTF-8",
-         "-Wconf:origin=scala.collection.compat.*:s"
-       )
-     else
-       Seq(
-         "-Xlint",
-         "-unchecked",
-         "-deprecation",
-         "-Xfatal-warnings",
-         "-Ywarn-inaccessible",
-         "-Ywarn-dead-code",
-         "-Ywarn-adapted-args",
-         "-Ywarn-nullary-unit",
-         "-feature",
-         "-Ywarn-unused",
-         "-Ywarn-unused-import",
-         "-encoding",
-         "UTF-8"
-       )),
+  scalacOptions := (
+    if (scala3.value) Scala3ScalacOptions
+    else if (scala213.value) Scala213ScalacOptions
+    else Scala212ScalacOptions
+    ),
   libraryDependencies ++= Seq(
     "org.scalatest" %% "scalatest" % "3.2.16" % "test"
   )

scalaj-collection/src/main/scala/com/daodecode/scalaj/collection/package.scala

@@ -13,8 +13,8 @@ package object collection extends StdLibDecorators with JavaAliases {
   /******************************************** deepAsJava converters ********************************************/
   implicit class DeepSeqAsJavaList[A](val scalaSeq: GenSeq[A]) extends AnyVal {
     private def toJava[T](genSeq: GenSeq[T]): JList[T] = genSeq match {
-      case buffer: MBuffer[T] => buffer.asJava
-      case mSeq: MSeq[T] => mSeq.asJava
+      case buffer: MBuffer[_] => buffer.asJava.asInstanceOf[JList[T]]
+      case mSeq: MSeq[_] => mSeq.asJava.asInstanceOf[JList[T]]
       case _ => genSeq.asJava
     }
 
@@ -104,7 +104,7 @@ package object collection extends StdLibDecorators with JavaAliases {
 
   implicit class DeepMapAsJavaMap[A, B](val scalaMap: GenMap[A, B]) extends AnyVal {
     private def toJava[T, U](genMap: GenMap[T, U]): JMap[T, U] = genMap match {
-      case mMap: MMap[T, U] => mMap.asJava
+      case mMap: MMap[_, _] => mMap.asJava.asInstanceOf[JMap[T, U]]
       case _ => genMap.asJava
     }
 

scalaj-collection/src/test/scala_2.13+/com/daodecode/scalaj/collection/test/SimpleJConvertersTest.scala

@@ -208,12 +208,12 @@ class SimpleJConvertersTest extends ScalaJSpec {
     "return same array with self conversions" in {
       {
         val scalaArray = Array("ss")
-        scalaArray.deepAsJava should be theSameInstanceAs scalaArray
+        scalaArray.deepAsJava[String] should be theSameInstanceAs scalaArray
       }
       {
         class A
         val scalaArray = Array(new A)
-        scalaArray.deepAsJava should be theSameInstanceAs scalaArray
+        scalaArray.deepAsJava[A] should be theSameInstanceAs scalaArray
       }
     }
 

scalaj-collection/src/test/scala_2.13+/com/daodecode/scalaj/collection/test/SimpleSConvertersTest.scala

@@ -115,20 +115,20 @@ class SimpleSConvertersTest extends ScalaJSpec with JListBuilder with JSetBuilde
     "return same array with primitives and self conversions" in {
       {
         val javaArray = Array[Int](1)
-        javaArray.deepAsScala should be theSameInstanceAs javaArray
+        javaArray.deepAsScala[Int] should be theSameInstanceAs javaArray
       }
       {
         val javaArray = Array[Char]('s')
-        javaArray.deepAsScala should be theSameInstanceAs javaArray
+        javaArray.deepAsScala[Char] should be theSameInstanceAs javaArray
       }
       {
         val javaArray = Array[Double](12d)
-        javaArray.deepAsScala should be theSameInstanceAs javaArray
+        javaArray.deepAsScala[Double] should be theSameInstanceAs javaArray
       }
       {
         class A
         val javaArray = Array[A](new A)
-        javaArray.deepAsScala should be theSameInstanceAs javaArray
+        javaArray.deepAsScala[A] should be theSameInstanceAs javaArray
       }
     }
   }