Full bootstrap: Use Dotty as the reference compiler

The non-bootstrapped compiler is now compiled by Dotty 0.14.0-RC1
instead of Scala 2.12.8. The bootstrapped compiler is compiled using the
non-bootstrapped compiler as before.

For now, we still support compilation with Scala 2.12, this is achieved
by having separate `src-2.x` and `src-3.x` directory for the library.

To use Scala 2.12 as the reference compiler, run:

++2.12.8

in sbt, or change `referenceVersion` to "2.12.8" in Build.scala.

Author: smarter

.drone.yml

@@ -52,6 +52,13 @@ pipeline:
       # sbt scripted tests are slow and only run on nightly or deployment
       event: [ tag, deployment ]
 
+  test_scala212:
+    group: test
+    image: lampepfl/dotty:2019-02-06
+    commands:
+      - cp -R . /tmp/5/ && cd /tmp/5/
+      - ./project/scripts/sbt ";++2.12.8 ;compile ;test"
+
   # DOCUMENTATION:
   documentation:
     image: lampepfl/dotty:2019-02-06

compiler/test/dotty/tools/TestSources.scala

@@ -65,7 +65,6 @@ object TestSources {
         .map(_.toString)
         .toList
 
-      assert(sources.nonEmpty)
       sources
     }
     finally files.close()

compiler/test/dotty/tools/dotc/CompilationTests.scala

@@ -232,7 +232,7 @@ class CompilationTests extends ParallelTesting {
       Array("-Ycheck-reentrant", "-Yemit-tasty-in-class")
     )
 
-    val libraryDirs = List(Paths.get("library/src"), Paths.get("library/src-bootstrapped"))
+    val libraryDirs = List(Paths.get("library/src"), Paths.get("library/src-3.x"), Paths.get("library/src-bootstrapped"))
     val librarySources = libraryDirs.flatMap(sources(_))
 
     val lib =

library/src-non-bootstrapped/dotty/DottyPredef.scala renamed to library/src-2.x/dotty/DottyPredef.scala

@@ -30,6 +30,7 @@ import scala.util.Properties.isJavaAtLeast
 
 object Build {
   val scalacVersion = "2.12.8"
+  val referenceVersion = "0.14.0-RC1"
 
   val baseVersion = "0.15.0"
   val baseSbtDottyVersion = "0.3.2"
@@ -182,21 +183,31 @@ object Build {
   // Settings used for projects compiled only with Java
   lazy val commonJavaSettings = commonSettings ++ Seq(
     version := dottyVersion,
-    scalaVersion := scalacVersion,
+    scalaVersion := referenceVersion,
+    // To be removed once we stop cross-compiling with Scala 2
+    crossScalaVersions := Seq(referenceVersion, scalacVersion),
     // Do not append Scala versions to the generated artifacts
     crossPaths := false,
     // Do not depend on the Scala library
     autoScalaLibrary := false
   )
 
-  // Settings used when compiling dotty using Scala 2
-  lazy val commonNonBootstrappedSettings = commonSettings ++ Seq(
+  // Settings used when compiling dotty (both non-boostrapped and bootstrapped)
+  lazy val commonDottySettings = commonSettings ++ Seq(
+    // Manually set the standard library to use
+    autoScalaLibrary := false
+  )
+
+  // Settings used when compiling dotty with the reference compiler
+  lazy val commonNonBootstrappedSettings = commonDottySettings ++ Seq(
     version := dottyNonBootstrappedVersion,
-    scalaVersion := scalacVersion
+    scalaVersion := referenceVersion,
+    // To be removed once we stop cross-compiling with Scala 2
+    crossScalaVersions := Seq(referenceVersion, scalacVersion)
   )
 
   // Settings used when compiling dotty with a non-bootstrapped dotty
-  lazy val commonBootstrappedSettings = commonSettings ++ Seq(
+  lazy val commonBootstrappedSettings = commonDottySettings ++ Seq(
     version := dottyVersion,
     scalaVersion := dottyNonBootstrappedVersion,
 
@@ -219,11 +230,6 @@ object Build {
     // sbt gets very unhappy if two projects use the same target
     target := baseDirectory.value / ".." / "out" / "bootstrap" / name.value,
 
-    // The non-bootstrapped dotty-library is not necessary when bootstrapping dotty
-    autoScalaLibrary := false,
-    // ...but scala-library is
-    libraryDependencies += "org.scala-lang" % "scala-library" % scalacVersion,
-
     // Compile using the non-bootstrapped and non-published dotty
     managedScalaInstance := false,
     scalaInstance := {
@@ -463,13 +469,20 @@ object Build {
             List("-XX:+TieredCompilation", "-XX:TieredStopAtLevel=1")
           else List()
 
+        val managedSrcDir = {
+          // Populate the directory
+          (managedSources in Compile).value
+
+          (sourceManaged in Compile).value
+        }
+
         val jarOpts = List(
-          "-Ddotty.tests.dottyCompilerManagedSources=" + (sourceManaged in Compile).value,
+          "-Ddotty.tests.dottyCompilerManagedSources=" + managedSrcDir,
           "-Ddotty.tests.classes.dottyInterfaces=" + jars("dotty-interfaces"),
           "-Ddotty.tests.classes.dottyLibrary=" + jars("dotty-library"),
           "-Ddotty.tests.classes.dottyCompiler=" + jars("dotty-compiler"),
           "-Ddotty.tests.classes.compilerInterface=" + findLib(attList, "compiler-interface"),
-          "-Ddotty.tests.classes.scalaLibrary=" + findLib(attList, "scala-library"),
+          "-Ddotty.tests.classes.scalaLibrary=" + findLib(attList, "scala-library-"),
           "-Ddotty.tests.classes.scalaAsm=" + findLib(attList, "scala-asm"),
           "-Ddotty.tests.classes.scalaXml=" + findLib(attList, "scala-xml"),
           "-Ddotty.tests.classes.jlineTerminal=" + findLib(attList, "jline-terminal"),
@@ -527,9 +540,6 @@ object Build {
         } else if (scalaLib == "") {
           println("Couldn't find scala-library on classpath, please run using script in bin dir instead")
         } else if (args.contains("-with-compiler")) {
-          if (!isDotty.value) {
-            throw new MessageOnlyException("-with-compiler can only be used with a bootstrapped compiler")
-          }
           val args1 = args.filter(_ != "-with-compiler")
           val asm = findLib(attList, "scala-asm")
           val dottyCompiler = jars("dotty-compiler")
@@ -580,7 +590,7 @@ object Build {
   def runCompilerMain(repl: Boolean = false) = Def.inputTaskDyn {
     val attList = (dependencyClasspath in Runtime).value
     val jars = packageAll.value
-    val scalaLib = findLib(attList, "scala-library")
+    val scalaLib = findLib(attList, "scala-library-")
     val dottyLib = jars("dotty-library")
     val dottyCompiler = jars("dotty-compiler")
     val args0: List[String] = spaceDelimited("<arg>").parsed.toList
@@ -598,12 +608,8 @@ object Build {
 
     var extraClasspath = s"$scalaLib${File.pathSeparator}$dottyLib"
     if ((decompile || printTasty) && !args.contains("-classpath")) extraClasspath += s"${File.pathSeparator}."
-    if (args0.contains("-with-compiler")) {
-      if (!isDotty.value) {
-        throw new MessageOnlyException("-with-compiler can only be used with a bootstrapped compiler")
-      }
+    if (args0.contains("-with-compiler"))
       extraClasspath += s"${File.pathSeparator}$dottyCompiler"
-    }
 
     val fullArgs = main :: insertClasspathInArgs(args, extraClasspath)
 
@@ -664,15 +670,32 @@ object Build {
   // Settings shared between dotty-library and dotty-library-bootstrapped
   lazy val dottyLibrarySettings = Seq(
     libraryDependencies += "org.scala-lang" % "scala-library" % scalacVersion,
+
+    // Needed so that the library sources are visible when `dotty.tools.dotc.core.Definitions#init` is called
+    scalacOptions in Compile ++= Seq("-sourcepath", (scalaSource in Compile).value.getAbsolutePath),
+
+    // To be removed once we stop cross-compiling with Scala 2
+    unmanagedSourceDirectories in Compile += {
+      val baseDir = baseDirectory.value
+      if (!isDotty.value)
+        baseDir / "src-2.x"
+      else
+        baseDir / "src-3.x"
+    },
+
     // Add version-specific source directories:
-    // - files in src-non-bootstrapped will only be compiled by the reference compiler (scalac)
+    // - files in src-non-bootstrapped will only be compiled by the reference compiler
     // - files in src-bootstrapped will only be compiled by the current dotty compiler (non-bootstrapped and bootstrapped)
-    unmanagedSourceDirectories in Compile += {
+    unmanagedSourceDirectories in Compile ++= {
       val baseDir = baseDirectory.value
-      if (isDotty.value)
-        baseDir / "src-bootstrapped"
+      if (isDotty.value) {
+        if (scalaVersion.value == referenceVersion)
+          Seq(baseDir / "src-non-bootstrapped")
+        else
+          Seq(baseDir / "src-bootstrapped")
+      }
       else
-        baseDir / "src-non-bootstrapped"
+        Seq()
     }
   )
 
@@ -949,8 +972,12 @@ object Build {
   val updateCommunityBuild = taskKey[Unit]("Updates the community build.")
 
   lazy val `community-build` = project.in(file("community-build")).
-    settings(commonNonBootstrappedSettings).
+    settings(commonSettings).
     settings(
+      scalaVersion := referenceVersion,
+      // To be removed once we stop cross-compiling with Scala 2
+      crossScalaVersions := Seq(referenceVersion, scalacVersion),
+
       prepareCommunityBuild := {
         (publishLocal in `dotty-sbt-bridge`).value
         (publishLocal in `dotty-interfaces`).value
@@ -1095,11 +1122,7 @@ object Build {
       settings(dottyCompilerSettings)
 
     def asDottyLibrary(implicit mode: Mode): Project = project.withCommonSettings.
-      settings(dottyLibrarySettings).
-      bootstrappedSettings(
-        // Needed so that the library sources are visible when `dotty.tools.dotc.core.Definitions#init` is called.
-        scalacOptions in Compile ++= Seq("-sourcepath", (scalaSource in Compile).value.getAbsolutePath)
-      )
+      settings(dottyLibrarySettings)
 
     def asDottyDoc(implicit mode: Mode): Project = project.withCommonSettings.
       dependsOn(dottyCompiler, dottyCompiler % "test->test").