Support scala milestone releases (with fixes for 2.13.0-M3) (#247)

* return full scala version for milestone releases

* complete support for scala 2.13.0-M2

* match 2.13 milestone releases for compiler bridge sources

* add hello world test case for scala 2.13.0-M3

5 files changed, 29 insertions, 7 deletions

diff --git a/scalalib/src/mill/scalalib/Lib.scala b/scalalib/src/mill/scalalib/Lib.scala
index d8fd9963..e6a7a255 100644
--- a/scalalib/src/mill/scalalib/Lib.scala
+++ b/scalalib/src/mill/scalalib/Lib.scala
@@ -16,7 +16,16 @@ case class CompilationResult(analysisFile: Path, classes: PathRef)
 
 object Lib{
 
-  def scalaBinaryVersion(scalaVersion: String) = scalaVersion.split('.').dropRight(1).mkString(".")
+  private val ReleaseVersion = raw"""(\d+)\.(\d+)\.(\d+)""".r
+  private val MinorSnapshotVersion = raw"""(\d+)\.(\d+)\.([1-9]\d*)-SNAPSHOT""".r
+
+  def scalaBinaryVersion(scalaVersion: String) = {
+    scalaVersion match {
+      case ReleaseVersion(major, minor, _) => s"$major.$minor"
+      case MinorSnapshotVersion(major, minor, _) => s"$major.$minor"
+      case _ => scalaVersion
+    }
+  }
 
   def grepJar(classPath: Agg[Path], s: String) = {
     classPath
diff --git a/scalalib/src/mill/scalalib/ScalaModule.scala b/scalalib/src/mill/scalalib/ScalaModule.scala
index 0fe7e3dc..b5106e3e 100644
--- a/scalalib/src/mill/scalalib/ScalaModule.scala
+++ b/scalalib/src/mill/scalalib/ScalaModule.scala
@@ -98,13 +98,20 @@ trait ScalaModule extends mill.Module with TaskModule { outer =>
 
   def platformSuffix = T{ "" }
 
-  def scalaCompilerBridgeSources = T{
+  private val Milestone213 = raw"""2.13.(\d+)-M(\d+)""".r
+
+  def scalaCompilerBridgeSources = T {
+    val (scalaVersion0, scalaBinaryVersion0) = scalaVersion() match {
+      case Milestone213(_, _) => ("2.13.0-M2", "2.13.0-M2")
+      case _ => (scalaVersion(), Lib.scalaBinaryVersion(scalaVersion()))
+    }
+
     resolveDependencies(
       repositories,
-      scalaVersion(),
+      scalaVersion0,
       Seq(ivy"org.scala-sbt::compiler-bridge:1.1.0"),
       sources = true
-    )
+    ).map(_.find(_.path.last == s"compiler-bridge_${scalaBinaryVersion0}-1.1.0-sources.jar").map(_.path).get)
   }
 
   def scalacPluginClasspath: T[Agg[PathRef]] = T {
@@ -154,7 +161,7 @@ trait ScalaModule extends mill.Module with TaskModule { outer =>
     scalaWorker.worker().compileScala(
       scalaVersion(),
       allSourceFiles().map(_.path),
-      scalaCompilerBridgeSources().map(_.path),
+      scalaCompilerBridgeSources(),
       compileClasspath().map(_.path),
       scalaCompilerClasspath().map(_.path),
       scalacOptions(),
diff --git a/scalalib/src/mill/scalalib/ScalaWorkerApi.scala b/scalalib/src/mill/scalalib/ScalaWorkerApi.scala
index 84db1dd8..a3760aed 100644
--- a/scalalib/src/mill/scalalib/ScalaWorkerApi.scala
+++ b/scalalib/src/mill/scalalib/ScalaWorkerApi.scala
@@ -54,7 +54,7 @@ trait ScalaWorkerModule extends mill.Module{
 trait ScalaWorkerApi {
   def compileScala(scalaVersion: String,
                    sources: Agg[Path],
-                   compileBridgeSources: Agg[Path],
+                   compilerBridgeSources: Path,
                    compileClasspath: Agg[Path],
                    compilerClasspath: Agg[Path],
                    scalacOptions: Seq[String],
diff --git a/scalalib/test/resources/hello-world/core/src-2.13/Shim.scala b/scalalib/test/resources/hello-world/core/src-2.13/Shim.scala
new file mode 100644
index 00000000..cedeb26b
--- /dev/null
+++ b/scalalib/test/resources/hello-world/core/src-2.13/Shim.scala
@@ -0,0 +1,5 @@
+object Shim{
+  def main(args: Array[String]): Unit = {
+    Main0(args(0), scala.util.Properties.versionNumberString + " idk")
+  }
+}
diff --git a/scalalib/test/src/mill/scalalib/HelloWorldTests.scala b/scalalib/test/src/mill/scalalib/HelloWorldTests.scala
index 61d2b724..8b7c459f 100644
--- a/scalalib/test/src/mill/scalalib/HelloWorldTests.scala
+++ b/scalalib/test/src/mill/scalalib/HelloWorldTests.scala
@@ -30,7 +30,7 @@ object HelloWorldTests extends TestSuite {
     object core extends HelloWorldModule
   }
   object CrossHelloWorld extends HelloBase {
-    object core extends Cross[HelloWorldCross]("2.10.6", "2.11.11", "2.12.3", "2.12.4")
+    object core extends Cross[HelloWorldCross]("2.10.6", "2.11.11", "2.12.3", "2.12.4", "2.13.0-M3")
     class HelloWorldCross(val crossScalaVersion: String) extends CrossScalaModule
   }
 
@@ -250,6 +250,7 @@ object HelloWorldTests extends TestSuite {
         'v211 - TestUtil.disableInJava9OrAbove(workspaceTest(CrossHelloWorld)(cross(_, "2.11.11", "2.11.11 pwns")))
         'v2123 - workspaceTest(CrossHelloWorld)(cross(_, "2.12.3", "2.12.3 leet"))
         'v2124 - workspaceTest(CrossHelloWorld)(cross(_, "2.12.4", "2.12.4 leet"))
+        'v2130M3 - workspaceTest(CrossHelloWorld)(cross(_, "2.13.0-M3", "2.13.0-M3 idk"))
       }