Flesh out `bridges` pre-compilation in Mill build, getting the cross-minor-version `AcyclicTests` running using the `mill` test runner

Fixed `Discovered` to only pick up public `Target`s, which makes it skip things like the `super$compile` of an overriden `compile` target.

Split up `sources` and `allSources`

TBD how to properly switch the `compilerBridgeJar` between the different output paths of SBT's compile-dir and Mill's compile-dir, and eventually to a maven-central artifact too

6 files changed, 59 insertions, 26 deletions

diff --git a/build.sbt b/build.sbt
index c1d8719b..3002eeb7 100644
--- a/build.sbt
+++ b/build.sbt
@@ -54,15 +54,8 @@ def bridge(bridgeVersion: String) = Project(
       val url =
         s"http://repo1.maven.org/maven2/org/scala-sbt/compiler-bridge_$v/1.0.5/compiler-bridge_$v-1.0.5-sources.jar"
       val curlDest = java.nio.file.Paths.get(target.value.toString, "sources")
-      if (java.nio.file.Files.exists(curlDest)) {
-        java.nio.file.Files.walk(curlDest)
-          .iterator()
-          .asScala
-          .toSeq
-          .reverse
-          .foreach(java.nio.file.Files.delete)
-      }
 
+      Seq("rm", "-rf", curlDest.toString).!
       java.nio.file.Files.createDirectories(curlDest)
 
       Seq("curl", "-L", "-o", curlDest.resolve("bridge.jar").toString, url).!
diff --git a/build.sc b/build.sc
index 6eb3de2b..7b261892 100755
--- a/build.sc
+++ b/build.sc
@@ -48,10 +48,45 @@ object Core extends MillModule {
     }
 }
 
+
+val bridges = for{
+  crossVersion <- mill.define.Cross("2.10.6", "2.11.8", "2.11.11", "2.12.3", "2.12.4")
+} yield new ScalaModule{
+  def basePath = pwd / 'bridge
+  def scalaVersion = crossVersion
+  override def allSources = T{
+
+    val v = crossVersion.split('.').dropRight(1).mkString(".")
+    val url =
+      s"http://repo1.maven.org/maven2/org/scala-sbt/compiler-bridge_$v/1.0.5/compiler-bridge_$v-1.0.5-sources.jar"
+    val curlDest = T.ctx().dest
+    implicit val pwd = curlDest
+    mkdir(curlDest)
+    rm(curlDest/"bridge.jar")
+
+    %("curl", "-L", "-o", curlDest / "bridge.jar", url)
+    %("unzip", curlDest / "bridge.jar" , "-d", curlDest / 'classes)
+
+
+    Seq(PathRef(curlDest / 'classes))
+  }
+  override def ivyDeps = Seq(
+    Dep.Java("org.scala-lang", "scala-compiler", crossVersion),
+    Dep.Java("org.scala-sbt", "compiler-interface", "1.0.5")
+  )
+}
 object ScalaPlugin extends MillModule {
 
   override def projectDeps = Seq(Core)
   def basePath = pwd / 'scalaplugin
+  override def compile = T.persistent[mill.eval.PathRef]{
+    bridges("2.10.6").compile()
+    bridges("2.11.8").compile()
+    bridges("2.11.11").compile()
+    bridges("2.12.3").compile()
+    bridges("2.12.4").compile()
+    super.compile()
+  }
   override def prependShellScript =
     "#!/usr/bin/env sh\n" +
     """exec java $JAVA_OPTS -cp "$0" mill.Main "$@" """
diff --git a/core/src/main/scala/mill/Main.scala b/core/src/main/scala/mill/Main.scala
index 1dbae4c3..db7a6c1a 100644
--- a/core/src/main/scala/mill/Main.scala
+++ b/core/src/main/scala/mill/Main.scala
@@ -26,14 +26,7 @@ object Main {
     query.parse(input)
   }
 
-  def renderSelector(selector: List[Mirror.Segment]) = {
-    val Mirror.Segment.Label(head) :: rest = selector
-    val stringSegments = rest.map{
-      case Mirror.Segment.Label(s) => "." + s
-      case Mirror.Segment.Cross(vs) => "[" + vs.mkString(",") + "]"
-    }
-    head + stringSegments.mkString
-  }
+
 
   def parseArgs(selectorString: String): Either[String, List[Mirror.Segment]] = {
     import fastparse.all.Parsed
@@ -81,7 +74,7 @@ object Main {
         def command = invokeCommand(hierarchy, last)
 
         command orElse target orElse runDefault.headOption.flatten match{
-          case None =>  Left("Cannot resolve task " + renderSelector(
+          case None =>  Left("Cannot resolve task " + Mirror.renderSelector(
             (Mirror.Segment.Label(last) :: revSelectorsSoFar).reverse)
           )
           case Some(either) => either
@@ -96,7 +89,7 @@ object Main {
               case (label, child) if label == singleLabel => child
             } match{
               case Some(child) => resolve(tail, child, obj, rest, remainingCrossSelectors, newRevSelectorsSoFar)
-              case None => Left("Cannot resolve module " + renderSelector(newRevSelectorsSoFar.reverse))
+              case None => Left("Cannot resolve module " + Mirror.renderSelector(newRevSelectorsSoFar.reverse))
             }
 
           case Mirror.Segment.Cross(cross) =>
@@ -105,7 +98,7 @@ object Main {
             if (crossOptions.contains(cross)){
               resolve(tail, childMirror, obj, rest, remainingCrossSelectors, newRevSelectorsSoFar)
             }else{
-              Left("Cannot resolve cross " + renderSelector(newRevSelectorsSoFar.reverse))
+              Left("Cannot resolve cross " + Mirror.renderSelector(newRevSelectorsSoFar.reverse))
             }
 
 
@@ -119,7 +112,7 @@ object Main {
     val discovered = implicitly[Discovered[T]]
     val consistencyErrors = Discovered.consistencyCheck(obj, discovered)
     if (consistencyErrors.nonEmpty) {
-      Left(s"Failed Discovered.consistencyCheck: $consistencyErrors")
+      Left(s"Failed Discovered.consistencyCheck: ${consistencyErrors.map(Mirror.renderSelector)}")
     } else {
       Right(discovered)
     }
@@ -138,7 +131,7 @@ object Main {
       (for((k, fs) <- evaluated.failing.items()) yield {
         val ks = k match{
           case Left(t) => t.toString
-          case Right(t) => renderSelector(t.segments.toList)
+          case Right(t) => Mirror.renderSelector(t.segments.toList)
         }
         val fss = fs.map{
           case Result.Exception(t) => t.toString
diff --git a/core/src/main/scala/mill/discover/Discovered.scala b/core/src/main/scala/mill/discover/Discovered.scala
index aef5f14f..753ac141 100644
--- a/core/src/main/scala/mill/discover/Discovered.scala
+++ b/core/src/main/scala/mill/discover/Discovered.scala
@@ -47,7 +47,8 @@ object Discovered {
         if m.isMethod &&
            m.typeSignature.paramLists.isEmpty &&
            m.typeSignature.resultType <:< c.weakTypeOf[Target[_]] &&
-           !m.name.toString.contains(' ')
+           !m.name.toString.contains(' ') &&
+           m.isPublic
       } yield {
         val x = Ident(TermName(c.freshName()))
         val t = q"""mill.discover.Mirror.makeTargetPoint(
diff --git a/core/src/main/scala/mill/discover/Mirror.scala b/core/src/main/scala/mill/discover/Mirror.scala
index 4dfeaa25..6293e599 100644
--- a/core/src/main/scala/mill/discover/Mirror.scala
+++ b/core/src/main/scala/mill/discover/Mirror.scala
@@ -25,6 +25,15 @@ case class Mirror[-T, V](node: (T, List[List[Any]]) => V,
 }
 
 object Mirror{
+  def renderSelector(selector: Seq[Mirror.Segment]) = {
+    val Mirror.Segment.Label(head) :: rest = selector.toList
+    val stringSegments = rest.map{
+      case Mirror.Segment.Label(s) => "." + s
+      case Mirror.Segment.Cross(vs) => "[" + vs.mkString(",") + "]"
+    }
+    head + stringSegments.mkString
+  }
+
   sealed trait Segment
   object Segment{
     case class Label(value: String) extends Segment
diff --git a/scalaplugin/src/main/scala/mill/scalaplugin/ScalaModule.scala b/scalaplugin/src/main/scala/mill/scalaplugin/ScalaModule.scala
index 27aefb12..3d194190 100644
--- a/scalaplugin/src/main/scala/mill/scalaplugin/ScalaModule.scala
+++ b/scalaplugin/src/main/scala/mill/scalaplugin/ScalaModule.scala
@@ -34,7 +34,7 @@ object ScalaModule{
 
   val compilerCache = new CompilerCache(2)
   def compileScala(scalaVersion: String,
-                   sources: Path,
+                   sources: Seq[Path],
                    compileClasspath: Seq[Path],
                    compilerClasspath: Seq[Path],
                    compilerBridge: Seq[Path],
@@ -54,7 +54,8 @@ object ScalaModule{
     val compilerJars = compilerClasspath.toArray.map(_.toIO)
 
     val compilerBridgeJar = new java.io.File(
-      s"bridge/${scalaVersion.replace('.', '_')}/target/scala-$binaryScalaVersion/mill-bridge_$scalaVersion-0.1-SNAPSHOT.jar"
+//      s"bridge/${scalaVersion.replace('.', '_')}/target/scala-$binaryScalaVersion/mill-bridge_$scalaVersion-0.1-SNAPSHOT.jar"
+      s"out/bridges/$scalaVersion/compile/classes"
     )
 
     val zincClassLoader = new URLClassLoader(compilerJars.map(_.toURI.toURL), null){
@@ -110,7 +111,7 @@ object ScalaModule{
     val newResult = ic.compile(
       ic.inputs(
         classpath = classesDir +: compileClasspathFiles,
-        sources = ls.rec(sources).filter(_.isFile).map(_.toIO).toArray,
+        sources = sources.flatMap(ls.rec).filter(x => x.isFile && x.ext == "scala").map(_.toIO).toArray,
         classesDirectory = classesDir,
         scalacOptions = scalacOptions.toArray,
         javacOptions = javacOptions.toArray,
@@ -334,10 +335,11 @@ trait ScalaModule extends Module with TaskModule{ outer =>
 
   def sources = T.source{ basePath / 'src }
   def resources = T.source{ basePath / 'resources }
+  def allSources = T{ Seq(sources()) }
   def compile = T.persistent{
     compileScala(
       scalaVersion(),
-      sources().path,
+      allSources().map(_.path),
       compileDepClasspath().map(_.path),
       scalaCompilerClasspath().map(_.path),
       compilerBridgeClasspath().map(_.path),