Add cross build for Scala 3

.travis.yml

@@ -8,16 +8,24 @@ scala:
   - 2.11.12
   - 2.12.12
   - 2.13.3
+  - 3.0.0-M1
 
 env:
   - SCALAJS_VERSION=       ADOPTOPENJDK=8
   - SCALAJS_VERSION=0.6.33 ADOPTOPENJDK=8
-  - SCALAJS_VERSION=1.3.0  ADOPTOPENJDK=8
+  - SCALAJS_VERSION=1.3.1  ADOPTOPENJDK=8
   - SCALAJS_VERSION=       ADOPTOPENJDK=11
   - SCALAJS_VERSION=0.6.33 ADOPTOPENJDK=11
-  - SCALAJS_VERSION=1.3.0  ADOPTOPENJDK=11
+  - SCALAJS_VERSION=1.3.1  ADOPTOPENJDK=11
 
 matrix:
+  exclude:
+    # Scala.js 0.6.x is not supported with Scala 3
+    - scala: 3.0.0-M1
+      env: SCALAJS_VERSION=0.6.33 ADOPTOPENJDK=8
+
+    - scala: 3.0.0-M1
+      env: SCALAJS_VERSION=0.6.33 ADOPTOPENJDK=11
 
   include:
 

build.sbt

@@ -31,6 +31,8 @@ lazy val root = project
     compat212JS,
     compat213JVM,
     compat213JS,
+    compat30JVM,
+    compat30JS,
     `scalafix-data211`,
     `scalafix-data212`,
     `scalafix-data213`,
@@ -51,6 +53,7 @@ lazy val junit = libraryDependencies += "com.novocode" % "junit-interface" % "0.
 lazy val scala211 = "2.11.12"
 lazy val scala212 = "2.12.12"
 lazy val scala213 = "2.13.3"
+lazy val scala30  = "3.0.0-M1"
 
 lazy val compat = MultiScalaCrossProject(JSPlatform, JVMPlatform, NativePlatform)(
   "compat",
@@ -62,7 +65,7 @@ lazy val compat = MultiScalaCrossProject(JSPlatform, JVMPlatform, NativePlatform
       scalacOptions ++= Seq("-feature", "-language:higherKinds", "-language:implicitConversions"),
       Compile / unmanagedSourceDirectories += {
         val sharedSourceDir = (ThisBuild / baseDirectory).value / "compat/src/main"
-        if (scalaVersion.value.startsWith("2.13.")) sharedSourceDir / "scala-2.13"
+        if (scalaVersion.value.startsWith("2.13.") || isDotty.value) sharedSourceDir / "scala-2.13"
         else sharedSourceDir / "scala-2.11_2.12"
       },
     )
@@ -79,13 +82,16 @@ lazy val compat = MultiScalaCrossProject(JSPlatform, JVMPlatform, NativePlatform
       },
     )
     .jsSettings(
-      scalacOptions += {
-        val x = (LocalRootProject / baseDirectory).value.toURI.toString
-        val y = "https://raw.githubusercontent.com/scala/scala-collection-compat/" + sys.process
-          .Process("git rev-parse HEAD")
-          .lineStream_!
-          .head
-        s"-P:scalajs:mapSourceURI:$x->$y/"
+      scalacOptions ++= {
+        if (isDotty.value) Seq() // Scala.js does not support -P with Scala 3: lampepfl/dotty#9783
+        else {
+          val x = (LocalRootProject / baseDirectory).value.toURI.toString
+          val y = "https://raw.githubusercontent.com/scala/scala-collection-compat/" + sys.process
+            .Process("git rev-parse HEAD")
+            .lineStream_!
+            .head
+          Seq(s"-P:scalajs:mapSourceURI:$x->$y/")
+        }
       },
       Test / fork := false // Scala.js cannot run forked tests
     )
@@ -102,6 +108,7 @@ lazy val compat = MultiScalaCrossProject(JSPlatform, JVMPlatform, NativePlatform
 val compat211 = compat(scala211)
 val compat212 = compat(scala212)
 val compat213 = compat(scala213)
+val compat30  = compat(scala30)
 
 lazy val compat211JVM    = compat211.jvm
 lazy val compat211JS     = compat211.js
@@ -110,6 +117,8 @@ lazy val compat212JVM    = compat212.jvm
 lazy val compat212JS     = compat212.js
 lazy val compat213JVM    = compat213.jvm
 lazy val compat213JS     = compat213.js
+lazy val compat30JVM     = compat30.jvm
+lazy val compat30JS      = compat30.js
 
 lazy val `binary-compat-old` = project
   .in(file("binary-compat/old"))

compat/src/test/scala/test/scala/collection/ArraySeqTest.scala

@@ -14,6 +14,7 @@ package test.scala.collection
 
 import org.junit.{Assert, Test}
 
+import scala.reflect.ClassTag
 import scala.collection.compat.immutable.ArraySeq
 
 // The unmodified ArraySeqTest from collection-strawman
@@ -53,22 +54,22 @@ class ArraySeqTest {
 
     def unit1(): Unit = {}
     def unit2(): Unit = {}
-    Assert.assertEquals(unit1, unit2)
+    Assert.assertEquals(unit1(), unit2())
     // unitArray is actually an instance of Immutable[BoxedUnit], the check to which is actually checked slice
     // implementation of ofRef
-    val unitArray: ArraySeq[Unit] = Array(unit1, unit2, unit1, unit2)
-    check(unitArray, Array(unit1, unit1), Array(unit1, unit1))
+    val unitArray: ArraySeq[Unit] = Array(unit1(), unit2(), unit1(), unit2())
+    check(unitArray, Array(unit1(), unit1()), Array(unit1(), unit1()))
   }
 
   private def check[T](array: ArraySeq[T],
                        expectedSliceResult1: ArraySeq[T],
-                       expectedSliceResult2: ArraySeq[T]) {
+                       expectedSliceResult2: ArraySeq[T])(implicit elemTag: ClassTag[T]): Unit = {
     Assert.assertEquals(array, array.slice(-1, 4))
     Assert.assertEquals(array, array.slice(0, 5))
     Assert.assertEquals(array, array.slice(-1, 5))
     Assert.assertEquals(expectedSliceResult1, array.slice(0, 2))
     Assert.assertEquals(expectedSliceResult2, array.slice(1, 3))
-    Assert.assertEquals(ArraySeq.empty[Nothing], array.slice(1, 1))
-    Assert.assertEquals(ArraySeq.empty[Nothing], array.slice(2, 1))
+    Assert.assertEquals(ArraySeq[T](), array.slice(1, 1))
+    Assert.assertEquals(ArraySeq[T](), array.slice(2, 1))
   }
 }

compat/src/test/scala/test/scala/collection/LazyListTest.scala

@@ -37,7 +37,7 @@ class LazyListTest {
     assertEquals(5, wf.map(identity).length) // success instead of NPE
   }
 
-  @Test(timeout = 10000) // scala/bug#6881
+  @Test(timeout = 10000L) // scala/bug#6881
   def test_reference_equality: Unit = {
     // Make sure we're tested with reference equality
     val s = LazyList.from(0)
@@ -192,7 +192,7 @@ class LazyListTest {
 
   val cycle1: LazyList[Int] = 1 #:: 2 #:: cycle1
   val cycle2: LazyList[Int] = 1 #:: 2 #:: 3 #:: cycle2
-  @Test(timeout = 10000)
+  @Test(timeout = 10000L)
   def testSameElements(): Unit = {
     assert(LazyList().sameElements(LazyList()))
     assert(!LazyList().sameElements(LazyList(1)))

project/MultiScalaProject.scala

@@ -44,6 +44,7 @@ trait MultiScala {
         val sourceDir = (ThisBuild / baseDirectory).value / base / "src" / "main"
         CrossVersion.partialVersion(scalaVersion.value) match {
           case Some((2, n)) if n >= 12 => List(sourceDir / "scala-2.12+")
+          case Some((3, _))            => List(sourceDir / "scala-2.13")
           case _                       => Nil
         }
       },

project/plugins.sbt

@@ -1,9 +1,10 @@
 val crossVer = "1.0.0"
 val scalaJSVersion =
-  Option(System.getenv("SCALAJS_VERSION")).filter(_.nonEmpty).getOrElse("0.6.33")
+  Option(System.getenv("SCALAJS_VERSION")).filter(_.nonEmpty).getOrElse("1.3.1")
 val scalaNativeVersion =
   Option(System.getenv("SCALANATIVE_VERSION")).filter(_.nonEmpty).getOrElse("0.3.9")
 
+addSbtPlugin("ch.epfl.lamp"           % "sbt-dotty"                     % "0.4.6")
 addSbtPlugin("org.scala-js"           % "sbt-scalajs"                   % scalaJSVersion)
 addSbtPlugin("org.portable-scala"     % "sbt-scalajs-crossproject"      % crossVer)
 addSbtPlugin("org.scala-native"       % "sbt-scala-native"              % scalaNativeVersion)