Add Scala 2.12 support (scala-native#1877)

The Scala 2.12 changelog can be found at
https://www.scala-lang.org/news/2.12.0/
This PR takes into account all the changes and adapts them for
Scala Native.

---

Lambdas

In order to keep the NIR changes to a minimum, we continue
generating a `FunctionN` class with an `apply` method for each
lambda. All the lambda captures are stored inside the class
instance and initialised via its constructor. The `apply` method
calls the generated `$anonfun` method, also extracting and
forwarding the captures.

---

NIR changes

Scala 2.12 now compiles trait methods as default methods in Java
interfaces. This means that the NIR was enhanced to support default
methods. The biggest impact of that is found in the reachability
analysis (`Reach.scala`).

---

Scala 2.11 cross-compilation

In order to keep the project compilable with Scala 2.11, a
`scala.scalanative.nscplugin.NirCompat` component is introduced in
`nscplugin`. This allows the compiler plugin to function with both
Scala 2.11 and 2.12.

In addition, some tests need to know under which Scala version they
are running. We use `sbt-buildinfo` to provide Scala version
information to the projects that need them (mainly for `unit-tests`
and `tools` tests).

---

Co-authored-by: Denys Shabalin <denys.shabalin@epfl.ch>

.travis.yml

@@ -2,6 +2,7 @@ sudo: required
 
 scala:
   - "2.11.12"
+  - "2.12.12"
 
 os: linux
 dist: trusty
@@ -36,7 +37,7 @@ script:
   - java -version
   - if [ "$MODE" == "source-checks" ]; then ./scripts/source-checks; fi
   - if [ "$MODE" == "test-tools" ]; then
-      sbt "-no-colors" "-J-Xmx3G" test-tools;
+      sbt "++ $TRAVIS_SCALA_VERSION -v" "-no-colors" "-J-Xmx3G" test-tools;
     fi
   - if [ "$MODE" == "test-runtime" ]; then
       ./ci-docker/load-cached-images.sh

build.sbt

@@ -2,10 +2,7 @@ import java.io.File.pathSeparator
 import scala.collection.mutable
 import scala.util.Try
 
-val sbt10Version          = "1.1.6" // minimum version
-val sbt10ScalaVersion     = "2.12.11"
-val libScalaVersion       = "2.11.12"
-val libCrossScalaVersions = Seq("2.11.8", "2.11.11", libScalaVersion)
+import build.ScalaVersions._
 
 // Convert "SomeName" to "some-name".
 def convertCamelKebab(name: String): String = {
@@ -38,7 +35,8 @@ inThisBuild(
   Def.settings(
     organization := "org.scala-native", // Maven <groupId>
     version := nativeVersion,           // Maven <version>
-    scalaVersion := libScalaVersion,
+    scalaVersion := scala212,
+    crossScalaVersions := libCrossScalaVersions,
     scalacOptions ++= Seq(
       "-deprecation",
       "-encoding",
@@ -48,7 +46,8 @@ inThisBuild(
       "-unchecked",
       "-Xfatal-warnings"
     )
-  ))
+  )
+)
 
 addCommandAlias(
   "test-all",
@@ -187,10 +186,22 @@ lazy val toolSettings: Seq[Setting[_]] =
   Def.settings(
     sbtVersion := sbt10Version,
     crossSbtVersions := List(sbt10Version),
-    scalaVersion := sbt10ScalaVersion,
+    crossScalaVersions := Seq(sbt10ScalaVersion),
     javacOptions ++= Seq("-encoding", "utf8")
   )
 
+lazy val buildInfoSettings: Seq[Setting[_]] =
+  Def.settings(
+    buildInfoPackage := "scala.scalanative.buildinfo",
+    buildInfoObject := "ScalaNativeBuildInfo",
+    buildInfoKeys := Seq[BuildInfoKey](
+      version,
+      sbtVersion,
+      scalaVersion,
+      "nativeScalaVersion" -> (nativelib / scalaVersion).value
+    )
+  )
+
 lazy val util =
   project
     .in(file("util"))
@@ -227,6 +238,8 @@ lazy val tools =
     .in(file("tools"))
     .settings(toolSettings)
     .settings(mavenPublishSettings)
+    .enablePlugins(BuildInfoPlugin)
+    .settings(buildInfoSettings)
     .settings(
       libraryDependencies ++= Seq(
         scalacheckDep,
@@ -280,8 +293,9 @@ lazy val sbtPluginSettings: Seq[Setting[_]] =
         scriptedLaunchOpts.value ++
           Seq("-Xmx1024M",
               "-XX:MaxMetaspaceSize=256M",
-              "-Dplugin.version=" + version.value) ++
-          ivyPaths.value.ivyHome.map(home => s"-Dsbt.ivy.home=${home}").toSeq
+              "-Dplugin.version=" + version.value,
+              "-Dscala.version=" + (nativelib / scalaVersion).value) ++
+          ivyPaths.value.ivyHome.map(home => s"-Dsbt.ivy.home=$home").toSeq
       }
     )
 
@@ -291,7 +305,7 @@ lazy val sbtScalaNative =
     .enablePlugins(SbtPlugin)
     .settings(sbtPluginSettings)
     .settings(
-      crossScalaVersions := libCrossScalaVersions,
+      crossScalaVersions := Seq(sbt10ScalaVersion),
       addSbtPlugin("org.portable-scala" % "sbt-platform-deps" % "1.0.0"),
       sbtTestDirectory := (ThisBuild / baseDirectory).value / "scripted-tests",
       // publish the other projects before running scripted tests.
@@ -395,14 +409,15 @@ lazy val scalalib =
     .in(file("scalalib"))
     .enablePlugins(MyScalaNativePlugin)
     .settings(
-      // This build uses libScalaVersion, which is currently 2.11.12
-      // to compile what appears to be 2.11.0 sources. This yields 114
+      // This build uses Scala 2.11 version 2.11.12 to compile
+      // what appears to be 2.11.0 sources. This yields 114
       // deprecations. Editing those sources is not an option (long story),
       // so do not spend compile time looking for the deprecations.
       // Keep the log file clean so that real issues stand out.
-      // This futzing can probably removed for scala >= 2.12.
       scalacOptions -= "-deprecation",
-      scalacOptions += "-deprecation:false"
+      scalacOptions += "-deprecation:false",
+      // The option below is needed since Scala 2.12.12.
+      scalacOptions += "-language:postfixOps"
     )
     .settings(mavenPublishSettings)
     .settings(
@@ -546,7 +561,8 @@ lazy val allCoreLibs: Project =
 lazy val tests =
   project
     .in(file("unit-tests"))
-    .enablePlugins(MyScalaNativePlugin)
+    .enablePlugins(MyScalaNativePlugin, BuildInfoPlugin)
+    .settings(buildInfoSettings)
     .settings(
       scalacOptions -= "-deprecation",
       scalacOptions += "-deprecation:false"
@@ -615,7 +631,7 @@ lazy val testingCompiler =
     )
     .dependsOn(testingCompilerInterface)
 
-lazy val testInterfaceCommonSourcesSettings = Seq(
+lazy val testInterfaceCommonSourcesSettings: Seq[Setting[_]] = Seq(
   unmanagedSourceDirectories in Compile += baseDirectory.value.getParentFile / "test-interface-common/src/main/scala",
   unmanagedSourceDirectories in Test += baseDirectory.value.getParentFile / "test-interface-common/src/test/scala"
 )
@@ -647,7 +663,6 @@ lazy val testRunner =
     .settings(mavenPublishSettings)
     .settings(testInterfaceCommonSourcesSettings)
     .settings(
-      crossScalaVersions := Seq(sbt10ScalaVersion),
       libraryDependencies ++= Seq(
         "org.scala-sbt" % "test-interface"  % "1.0",
         "com.novocode"  % "junit-interface" % "0.11" % "test"
@@ -716,7 +731,7 @@ lazy val junitTestOutputsJVM =
     .in(file("junit-test/output-jvm"))
     .settings(
       commonJUnitTestOutputsSettings,
-      scalaVersion := sbt10ScalaVersion,
+      crossScalaVersions := Seq(sbt10ScalaVersion),
       libraryDependencies ++= Seq(
         "com.novocode" % "junit-interface" % "0.11" % "test"
       )
@@ -737,7 +752,7 @@ lazy val junitAsyncJVM =
   project
     .in(file("junit-async/jvm"))
     .settings(
-      scalaVersion := sbt10ScalaVersion,
+      crossScalaVersions := Seq(sbt10ScalaVersion),
       nameSettings,
       publishArtifact := false
     )

ci-docker/Dockerfile

@@ -47,4 +47,4 @@ USER scala-native
 
 WORKDIR /home/scala-native/scala-native
 
-CMD sbt -no-colors -J-Xmx3G "set scriptedBufferLog in sbtScalaNative := false" "$TEST_COMMAND"
+CMD sbt "++ $TRAVIS_SCALA_VERSION -v" -no-colors -J-Xmx3G "set scriptedBufferLog in sbtScalaNative := false" "$TEST_COMMAND"

ci-docker/run-test.sh

@@ -10,4 +10,5 @@ docker run -v $HOME/.ivy2:/home/scala-native/.ivy2 \
            -e SCALANATIVE_GC=$SCALANATIVE_GC \
            -e SCALANATIVE_OPTIMIZE=$SCALANATIVE_OPTIMIZE \
            -e TEST_COMMAND=$TEST_COMMAND \
+           -e TRAVIS_SCALA_VERSION=$TRAVIS_SCALA_VERSION \
            -it scala-native-testing:linux-$TARGET_DOCKER_PLATFORM;

javalib/src/main/scala/java/lang/Boolean.scala

@@ -43,7 +43,8 @@ final class Boolean(val _value: scala.Boolean) extends Comparable[Boolean] {
 }
 
 object Boolean {
-  final val TYPE           = classOf[scala.Boolean]
+  final val TYPE =
+    scala.Predef.classOf[scala.scalanative.runtime.PrimitiveBoolean]
   final val TRUE: Boolean  = new Boolean(true)
   final val FALSE: Boolean = new Boolean(false)
 

javalib/src/main/scala/java/lang/Byte.scala

@@ -77,11 +77,11 @@ final class Byte(val _value: scala.Byte) extends Number with Comparable[Byte] {
   protected def +(x: String): String = _value + x
 
   protected def <<(x: scala.Int): scala.Int   = _value << x
-  protected def <<(x: scala.Long): scala.Int  = _value << x
+  protected def <<(x: scala.Long): scala.Int  = _value << x.toInt
   protected def >>>(x: scala.Int): scala.Int  = _value >>> x
-  protected def >>>(x: scala.Long): scala.Int = _value >>> x
+  protected def >>>(x: scala.Long): scala.Int = _value >>> x.toInt
   protected def >>(x: scala.Int): scala.Int   = _value >> x
-  protected def >>(x: scala.Long): scala.Int  = _value >> x
+  protected def >>(x: scala.Long): scala.Int  = _value >> x.toInt
 
   protected def <(x: scala.Byte): scala.Boolean   = _value < x
   protected def <(x: scala.Short): scala.Boolean  = _value < x
@@ -175,7 +175,7 @@ final class Byte(val _value: scala.Byte) extends Number with Comparable[Byte] {
 }
 
 object Byte {
-  final val TYPE  = classOf[scala.Byte]
+  final val TYPE  = scala.Predef.classOf[scala.scalanative.runtime.PrimitiveByte]
   final val SIZE  = 8
   final val BYTES = 1
 

javalib/src/main/scala/java/lang/Character.scala

@@ -65,11 +65,11 @@ class Character(val _value: scala.Char)
   protected def +(x: String): String = _value + x
 
   protected def <<(x: scala.Int): scala.Int   = _value << x
-  protected def <<(x: scala.Long): scala.Int  = _value << x
+  protected def <<(x: scala.Long): scala.Int  = _value << x.toInt
   protected def >>>(x: scala.Int): scala.Int  = _value >>> x
-  protected def >>>(x: scala.Long): scala.Int = _value >>> x
+  protected def >>>(x: scala.Long): scala.Int = _value >>> x.toInt
   protected def >>(x: scala.Int): scala.Int   = _value >> x
-  protected def >>(x: scala.Long): scala.Int  = _value >> x
+  protected def >>(x: scala.Long): scala.Int  = _value >> x.toInt
 
   protected def ==(x: scala.Byte): scala.Boolean   = _value == x
   protected def ==(x: scala.Short): scala.Boolean  = _value == x
@@ -179,7 +179,7 @@ class Character(val _value: scala.Char)
 }
 
 object Character {
-  final val TYPE      = classOf[scala.Char]
+  final val TYPE      = scala.Predef.classOf[scala.scalanative.runtime.PrimitiveChar]
   final val MIN_VALUE = '\u0000'
   final val MAX_VALUE = '\uffff'
   final val SIZE      = 16

javalib/src/main/scala/java/lang/Double.scala

@@ -193,7 +193,8 @@ object Double {
   final val NEGATIVE_INFINITY = 1.0 / -0.0
   final val POSITIVE_INFINITY = 1.0 / 0.0
   final val SIZE              = 64
-  final val TYPE              = classOf[scala.Double]
+  final val TYPE =
+    scala.Predef.classOf[scala.scalanative.runtime.PrimitiveDouble]
 
   @inline def compare(x: scala.Double, y: scala.Double): scala.Int =
     if (x > y) 1

javalib/src/main/scala/java/lang/Float.scala

@@ -189,7 +189,8 @@ object Float {
   final val NEGATIVE_INFINITY = 1.0f / -0.0f
   final val POSITIVE_INFINITY = 1.0f / 0.0f
   final val SIZE              = 32
-  final val TYPE              = classOf[scala.Float]
+  final val TYPE =
+    scala.Predef.classOf[scala.scalanative.runtime.PrimitiveFloat]
 
   @inline def compare(x: scala.Float, y: scala.Float): scala.Int =
     if (x > y) 1

javalib/src/main/scala/java/lang/Integer.scala

@@ -80,11 +80,11 @@ final class Integer(val _value: scala.Int)
   protected def +(x: String): String = _value + x
 
   protected def <<(x: scala.Int): scala.Int   = _value << x
-  protected def <<(x: scala.Long): scala.Int  = _value << x
+  protected def <<(x: scala.Long): scala.Int  = _value << x.toInt
   protected def >>>(x: scala.Int): scala.Int  = _value >>> x
-  protected def >>>(x: scala.Long): scala.Int = _value >>> x
+  protected def >>>(x: scala.Long): scala.Int = _value >>> x.toInt
   protected def >>(x: scala.Int): scala.Int   = _value >> x
-  protected def >>(x: scala.Long): scala.Int  = _value >> x
+  protected def >>(x: scala.Long): scala.Int  = _value >> x.toInt
 
   protected def <(x: scala.Byte): scala.Boolean   = _value < x
   protected def <(x: scala.Short): scala.Boolean  = _value < x
@@ -189,7 +189,7 @@ private[lang] object IntegerCache {
 object Integer {
   import IntegerDecimalScale.decimalScale
 
-  final val TYPE      = classOf[scala.Int]
+  final val TYPE      = scala.Predef.classOf[scala.scalanative.runtime.PrimitiveInt]
   final val MIN_VALUE = -2147483648
   final val MAX_VALUE = 2147483647
   final val SIZE      = 32

javalib/src/main/scala/java/lang/Long.scala

@@ -183,7 +183,7 @@ final class Long(val _value: scala.Long) extends Number with Comparable[Long] {
 }
 
 object Long {
-  final val TYPE      = classOf[scala.Long]
+  final val TYPE      = scala.Predef.classOf[scala.scalanative.runtime.PrimitiveLong]
   final val MIN_VALUE = -9223372036854775808L
   final val MAX_VALUE = 9223372036854775807L
   final val SIZE      = 64

javalib/src/main/scala/java/lang/Short.scala

@@ -78,11 +78,11 @@ final class Short(val _value: scala.Short)
   protected def +(x: String): String = _value + x
 
   protected def <<(x: scala.Int): scala.Int   = _value << x
-  protected def <<(x: scala.Long): scala.Int  = _value << x
+  protected def <<(x: scala.Long): scala.Int  = _value << x.toInt
   protected def >>>(x: scala.Int): scala.Int  = _value >>> x
-  protected def >>>(x: scala.Long): scala.Int = _value >>> x
+  protected def >>>(x: scala.Long): scala.Int = _value >>> x.toInt
   protected def >>(x: scala.Int): scala.Int   = _value >> x
-  protected def >>(x: scala.Long): scala.Int  = _value >> x
+  protected def >>(x: scala.Long): scala.Int  = _value >> x.toInt
 
   protected def <(x: scala.Byte): scala.Boolean   = _value < x
   protected def <(x: scala.Short): scala.Boolean  = _value < x
@@ -176,7 +176,8 @@ final class Short(val _value: scala.Short)
 }
 
 object Short {
-  final val TYPE  = classOf[scala.Short]
+  final val TYPE =
+    scala.Predef.classOf[scala.scalanative.runtime.PrimitiveShort]
   final val SIZE  = 16
   final val BYTES = 2
 

javalib/src/main/scala/java/nio/file/Files.scala

@@ -735,8 +735,8 @@ object Files {
 
   private def setAttributes(path: Path, attrs: Array[FileAttribute[_]]): Unit =
     attrs.map(a => (a.name, a.value)).toMap.foreach {
-      case (name, value: Object) =>
-        setAttribute(path, name, value, Array.empty)
+      case (name, value) =>
+        setAttribute(path, name, value.asInstanceOf[AnyRef], Array.empty)
     }
 
   private val attributesClassesToViews

nativelib/src/main/scala/scala/scalanative/unsigned/UInt.scala

@@ -49,7 +49,7 @@ final class UInt private[scalanative] (private[scalanative] val underlying: Int)
    *         filling in the new right bits with zeroes.
    * @example {{{ 6 << 3 == 48 // in binary: 0110 << 3 == 0110000 }}}
    */
-  @inline final def <<(x: Long): UInt = new UInt(underlying << x)
+  @inline final def <<(x: Long): UInt = new UInt(underlying << x.toInt)
 
   /**
    * Returns this value bit-shifted right by the specified number of bits,
@@ -73,7 +73,7 @@ final class UInt private[scalanative] (private[scalanative] val underlying: Int)
    * //            00011111 11111111 11111111 11111101
    * }}}
    */
-  @inline final def >>>(x: Long): UInt = new UInt(underlying >>> x)
+  @inline final def >>>(x: Long): UInt = new UInt(underlying >>> x.toInt)
 
   /**
    * Returns this value bit-shifted left by the specified number of bits,
@@ -95,7 +95,7 @@ final class UInt private[scalanative] (private[scalanative] val underlying: Int)
    * //            11111111 11111111 11111111 11111101
    * }}}
    */
-  @inline final def >>(x: Long): UInt = new UInt(underlying >> x)
+  @inline final def >>(x: Long): UInt = new UInt(underlying >> x.toInt)
 
   @inline final override def compareTo(x: UInt): Int =
     JInteger.compareUnsigned(underlying, x.underlying)

nir/src/main/scala/scala/scalanative/nir/Attrs.scala

@@ -32,7 +32,7 @@ object Attr {
   final case object Abstract          extends Attr
 }
 
-final case class Attrs(inline: Inline = MayInline,
+final case class Attrs(inlineHint: Inline = MayInline,
                        specialize: Specialize = MaySpecialize,
                        opt: Opt = UnOpt,
                        isExtern: Boolean = false,
@@ -43,7 +43,7 @@ final case class Attrs(inline: Inline = MayInline,
   def toSeq: Seq[Attr] = {
     val out = mutable.UnrolledBuffer.empty[Attr]
 
-    if (inline != MayInline) out += inline
+    if (inlineHint != MayInline) out += inlineHint
     if (specialize != MaySpecialize) out += specialize
     if (opt != UnOpt) out += opt
     if (isExtern) out += Extern
@@ -58,8 +58,8 @@ final case class Attrs(inline: Inline = MayInline,
 object Attrs {
   val None = new Attrs()
 
-  def fromSeq(attrs: Seq[Attr]) = {
-    var inline     = None.inline
+  def fromSeq(attrs: Seq[Attr]): Attrs = {
+    var inline     = None.inlineHint
     var specialize = None.specialize
     var opt        = None.opt
     var isExtern   = false