make mainClass discovery work in ScalaJSModule#run

Also disable ScalaJSModule#runMain, since the official Scala.js-SBT plugin does not support it and it requires an expensive re-linking every time it is run.

4 files changed, 42 insertions, 67 deletions

diff --git a/scalajslib/jsbridges/0.6/src/mill/scalajslib/bridge/ScalaJSBridge.scala b/scalajslib/jsbridges/0.6/src/mill/scalajslib/bridge/ScalaJSBridge.scala
index 604df3f7..86abbd14 100644
--- a/scalajslib/jsbridges/0.6/src/mill/scalajslib/bridge/ScalaJSBridge.scala
+++ b/scalajslib/jsbridges/0.6/src/mill/scalajslib/bridge/ScalaJSBridge.scala
@@ -37,7 +37,7 @@ class ScalaJSBridge extends mill.scalajslib.ScalaJSBridge {
     val env = new NodeJSEnv().loadLibs(
       Seq(ResolvedJSDependency.minimal(new FileVirtualJSFile(linkedFile)))
     )
-    val jsConsole = ConsoleJSConsole
+
     val config = TestAdapter.Config().withLogger(new ScalaConsoleLogger)
     val adapter =
       new TestAdapter(env, config)
diff --git a/scalajslib/src/mill/scalajslib/ScalaJSModule.scala b/scalajslib/src/mill/scalajslib/ScalaJSModule.scala
index b3cc28a4..5a3b6526 100644
--- a/scalajslib/src/mill/scalajslib/ScalaJSModule.scala
+++ b/scalajslib/src/mill/scalajslib/ScalaJSModule.scala
@@ -4,7 +4,7 @@ package scalajslib
 import ammonite.ops.{Path, exists, ls, mkdir, rm}
 import coursier.Cache
 import coursier.maven.MavenRepository
-import mill.eval.PathRef
+import mill.eval.{PathRef, Result}
 import mill.eval.Result.Success
 import mill.scalalib.Lib.resolveDependencies
 import mill.scalalib.{CompilationResult, Dep, DepSyntax, TestModule}
@@ -71,7 +71,7 @@ trait ScalaJSModule extends scalalib.ScalaModule { outer =>
       ScalaJSBridge.scalaJSBridge(),
       toolsClasspath(),
       runClasspath(),
-      mainClass(),
+      finalMainClassOpt().toOption,
       FastOpt
     )
   }
@@ -81,39 +81,32 @@ trait ScalaJSModule extends scalalib.ScalaModule { outer =>
       ScalaJSBridge.scalaJSBridge(),
       toolsClasspath(),
       runClasspath(),
-      mainClass(),
+      finalMainClassOpt().toOption,
       FullOpt
     )
   }
 
-  override  def runLocal(args: String*) = T.command { run(args:_*) }
+  override def runLocal(args: String*) = T.command { run(args:_*) }
 
   override def run(args: String*) = T.command {
-    if(mainClass().isEmpty) {
-      throw new RuntimeException("No mainClass provided!")
+    finalMainClassOpt() match{
+      case Left(err) => Result.Failure(err)
+      case Right(_) =>
+        ScalaJSBridge.scalaJSBridge().run(
+          toolsClasspath().map(_.path),
+          fastOpt().path.toIO
+        )
+        Result.Success(())
     }
 
-    ScalaJSBridge.scalaJSBridge().run(
-      toolsClasspath().map(_.path),
-      fastOpt().path.toIO
-    )
   }
 
-  override def runMainLocal(mainClass: String, args: String*) = T.command { runMain(mainClass, args:_*) }
-
-  override def runMain(mainClass: String, args: String*) = T.command {
-    val linkedFile = link(
-      ScalaJSBridge.scalaJSBridge(),
-      toolsClasspath(),
-      runClasspath(),
-      Some(mainClass),
-      FastOpt
-    )
+  override def runMainLocal(mainClass: String, args: String*) = T.command[Unit] {
+    mill.eval.Result.Failure("runMain is not supported in Scala.js")
+  }
 
-    ScalaJSBridge.scalaJSBridge().run(
-      toolsClasspath().map(_.path),
-      linkedFile.path.toIO
-    )
+  override def runMain(mainClass: String, args: String*) = T.command[Unit] {
+    mill.eval.Result.Failure("runMain is not supported in Scala.js")
   }
 
   def link(worker: ScalaJSWorker,
diff --git a/scalajslib/test/src/mill/scalajslib/HelloJSWorldTests.scala b/scalajslib/test/src/mill/scalajslib/HelloJSWorldTests.scala
index 23db8cf6..2429a189 100644
--- a/scalajslib/test/src/mill/scalajslib/HelloJSWorldTests.scala
+++ b/scalajslib/test/src/mill/scalajslib/HelloJSWorldTests.scala
@@ -204,11 +204,8 @@ object HelloJSWorldTests extends TestSuite {
 //      'scalaTest_2124_100M2 - checkScalaTest("2.12.4", "1.0.0-M2")
     }
 
-    def checkRun(scalaVersion: String, scalaJSVersion: String, mainClass: Option[String] = None): Unit = {
-      val task = mainClass match {
-        case Some(main) => HelloJSWorld.helloJsWorld(scalaVersion, scalaJSVersion).runMain(main)
-        case None => HelloJSWorld.helloJsWorld(scalaVersion, scalaJSVersion).run()
-      }
+    def checkRun(scalaVersion: String, scalaJSVersion: String): Unit = {
+      val task = HelloJSWorld.helloJsWorld(scalaVersion, scalaJSVersion).run()
 
       val Right((_, evalCount)) = helloWorldEvaluator(task)
 
@@ -224,24 +221,6 @@ object HelloJSWorldTests extends TestSuite {
       )
     }
 
-    'runMain - {
-      val mainClass = Some("Main")
-      'run_2118_0622  - checkRun("2.11.8", "0.6.22", mainClass)
-      'run_2124_0622  - checkRun("2.12.4", "0.6.22", mainClass)
-      'run_2118_100M2 - checkRun("2.11.8", "1.0.0-M2", mainClass)
-      'run_2124_100M2 - checkRun("2.12.4", "1.0.0-M2", mainClass)
-
-      'wrongMain - {
-        val wrongMainClass = "Foo"
-        val task = HelloJSWorld.helloJsWorld("2.12.4", "0.6.22").runMain(wrongMainClass)
-
-        val Left(Result.Exception(ex, _)) = helloWorldEvaluator(task)
-
-        assert(
-          ex.isInstanceOf[Exception]
-        )
-      }
-    }
     'run - {
       'run_2118_0622  - checkRun("2.11.8", "0.6.22")
       'run_2124_0622  - checkRun("2.12.4", "0.6.22")
diff --git a/scalalib/src/mill/scalalib/ScalaModule.scala b/scalalib/src/mill/scalalib/ScalaModule.scala
index cc2d1e84..c7dbc322 100644
--- a/scalalib/src/mill/scalalib/ScalaModule.scala
+++ b/scalalib/src/mill/scalalib/ScalaModule.scala
@@ -29,22 +29,29 @@ trait ScalaModule extends mill.Module with TaskModule { outer =>
 
   def scalaWorker: ScalaWorkerModule = mill.scalalib.ScalaWorkerModule
 
-  def finalMainClass: T[String] = T{
-    mainClass() match {
-      case Some(main) => Result.Success(main)
+  def finalMainClassOpt: T[Either[String, String]] = T{
+    mainClass() match{
+      case Some(m) => Right(m)
       case None =>
-        scalaWorker.worker().discoverMainClasses(compile()) match {
-          case Seq() => Result.Failure("No main class specified or found")
-          case Seq(main) => Result.Success(main)
+        scalaWorker.worker().discoverMainClasses(compile())match {
+          case Seq() => Left("No main class specified or found")
+          case Seq(main) => Right(main)
           case mains =>
-            Result.Failure(
+            Left(
               s"Multiple main classes found (${mains.mkString(",")}) " +
-              "please explicitly specify which one to use by overriding mainClass"
+                "please explicitly specify which one to use by overriding mainClass"
             )
         }
     }
   }
 
+  def finalMainClass: T[String] = T{
+    finalMainClassOpt() match {
+      case Right(main) => Result.Success(main)
+      case Left(msg)   => Result.Failure(msg)
+    }
+  }
+
   def ivyDeps = T{ Agg.empty[Dep] }
   def compileIvyDeps = T{ Agg.empty[Dep] }
   def scalacPluginIvyDeps = T{ Agg.empty[Dep] }
@@ -215,17 +222,13 @@ trait ScalaModule extends mill.Module with TaskModule { outer =>
   def forkEnv = T{ sys.env.toMap }
 
   def launcher = T{
-    mainClass() match {
-      case None => Result.Failure("Need to specify a main class for launcher")
-      case Some(cls) =>
-        Result.Success(
-          Jvm.createLauncher(
-            cls,
-            runClasspath().map(_.path),
-            forkArgs()
-          )
-        )
-    }
+    Result.Success(
+      Jvm.createLauncher(
+        finalMainClass(),
+        runClasspath().map(_.path),
+        forkArgs()
+      )
+    )
   }
 
   def runLocal(args: String*) = T.command {