Enable colored output for Scala 2

scalalib/test/resources/hello-world-color-output/core/src/Main.scala

@@ -0,0 +1,12 @@
+package example
+
+trait Show[A]
+
+object Show {
+ implicit def option[A](implicit s: Show[A]): Show[Option[A]] = ???
+}
+
+object Example {
+ def main(args: Array[String]): Unit =
+ println(implicitly[Show[Option[String]]])
+}

scalalib/test/src/mill/scalalib/HelloWorldTests.scala

@@ -1,6 +1,6 @@
 package mill.scalalib
 
-import java.io.ByteArrayOutputStream
+import java.io.{ByteArrayOutputStream, PrintStream}
 import java.util.jar.JarFile
 import scala.jdk.CollectionConverters._
 import scala.util.{Properties, Using}
@@ -283,6 +283,16 @@ object HelloWorldTests extends TestSuite {
  }
  }
 
+ object HelloWorldColorOutput extends HelloBase {
+ object core extends ScalaModule {
+ def scalaVersion = scala213Version
+
+ override def scalacOptions = super.scalacOptions() ++ Seq(
+ "-Vimplicits"
+ )
+ }
+ }
+
  object HelloScalacheck extends HelloBase {
  object foo extends ScalaModule {
  def scalaVersion = scala212Version
@@ -420,9 +430,10 @@ object HelloWorldTests extends TestSuite {
  m: TestUtil.BaseModule,
  resourcePath: os.Path = resourcePath,
  env: Map[String, String] = Evaluator.defaultEnv,
- debug: Boolean = false
+ debug: Boolean = false,
+ errStream: PrintStream = System.err
  )(t: TestEvaluator => T)(implicit tp: TestPath): T = {
- val eval = new TestEvaluator(m, env = env, debugEnabled = debug)
+ val eval = new TestEvaluator(m, env = env, debugEnabled = debug, errStream = errStream)
  os.remove.all(m.millSourcePath)
  os.remove.all(eval.outPath)
  os.makeDir.all(m.millSourcePath / os.up)
@@ -1189,6 +1200,20 @@ object HelloWorldTests extends TestSuite {
  assert(evalCount > 0)
  }
  }
+ "color-output" - {
+ val errStream = new ByteArrayOutputStream()
+ workspaceTest(
+ HelloWorldColorOutput,
+ os.pwd / "scalalib" / "test" / "resources" / "hello-world-color-output",
+ errStream = new PrintStream(errStream, true)
+ ) { eval =>
+
+ val Left(Result.Failure("Compilation failed", _)) = eval.apply(HelloWorldColorOutput.core.compile)
+ val output = errStream.toString
+ assert(output.contains(s"${Console.RED}!${Console.RESET}${Console.BLUE}I"))
+ assert(output.contains(s"${Console.GREEN}example.Show[scala.Option[java.lang.String]]${Console.RESET}"))
+ }
+ }
 
  "scalacheck" - workspaceTest(
  HelloScalacheck,

scalalib/worker/src/mill/scalalib/worker/ZincWorkerImpl.scala

@@ -534,7 +534,10 @@ class ZincWorkerImpl(
  stampReader = Stamps.timeWrapBinaryStamps(converter)
  )
 
+ val scalaColorProp = "scala.color"
+ val previousScalaColor = sys.props.get(scalaColorProp).getOrElse("auto")
  try {
+ sys.props(scalaColorProp) = if (ctx.log.colored) "true" else "false"
  val newResult = ic.compile(
  in = inputs,
  logger = logger
@@ -557,6 +560,7 @@ class ZincWorkerImpl(
  } finally {
  reporter.foreach(r => sources.foreach(r.fileVisited(_)))
  reporter.foreach(_.finish())
+ sys.props(scalaColorProp) = previousScalaColor
  }
  }