Support mill init from an existing sbt project, and improve related Maven and Gradle support

.github/actions/post-build-setup/action.yml

@@ -34,4 +34,6 @@ runs:
         name: ${{ inputs.os }}-selective-execution-artifact
 
     - run: mv out/mill-selective-execution/mill-selective-execution.json out/mill-selective-execution.json
-      shell: bash
+      shell: bash
+
+    - uses: sbt/setup-sbt@v1

.github/actions/pre-build-setup/action.yml

@@ -65,4 +65,4 @@ runs:
     - uses: actions/checkout@v4
 
     - run: echo temurin:${{ inputs.java-version }} > .mill-jvm-version
-      shell: bash
+      shell: bash

.github/workflows/autofix.yml

@@ -7,6 +7,8 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
+      - uses: sbt/setup-sbt@v1
+
       - run: |
           ./mill __.fix + mill.javalib.palantirformat.PalantirFormatModule/ + mill.scalalib.scalafmt.ScalafmtModule/ + mill.kotlinlib.ktlint.KtlintModule/
           ./mill --meta-level 1 mill.scalalib.scalafmt.ScalafmtModule/

build.mill

@@ -55,6 +55,7 @@ object Deps {
   val scala2Version = "2.13.15"
   // The Scala 2.12.x version to use for some workers
   val workerScalaVersion212 = "2.12.20"
+  val sbtScalaVersion212 = workerScalaVersion212
 
   val testScala213Version = "2.13.15"
   // Scala Native 4.2 will not get releases for new Scala version
@@ -220,6 +221,7 @@ object Deps {
     ivy"org.apache.maven.resolver:maven-resolver-transport-wagon:$mavenResolverVersion"
   val coursierJvmIndexVersion = "0.0.4-84-f852c6"
   val gradleApi = ivy"dev.gradleplugins:gradle-api:8.11.1"
+  val sbt = ivy"org.scala-sbt:sbt:1.10.10"
 
   object RuntimeDeps {
     val dokkaVersion = "2.0.0"
@@ -569,7 +571,8 @@ trait MillBaseTestsModule extends TestModule {
       s"-DTEST_TEST_INTERFACE_VERSION=${Deps.sbtTestInterface.version}",
       s"-DTEST_ZIOTEST_VERSION=${Deps.TestDeps.zioTest.version}",
       s"-DTEST_ZINC_VERSION=${Deps.zinc.version}",
-      s"-DTEST_KOTLIN_VERSION=${Deps.kotlinCompiler.version}"
+      s"-DTEST_KOTLIN_VERSION=${Deps.kotlinCompiler.version}",
+      s"-DTEST_SBT_VERSION=${Deps.sbt.version}"
     )
   }
 
@@ -714,8 +717,10 @@ trait MillStableScalaModule extends MillPublishScalaModule with Mima {
   }
 }
 
+trait MillPublishCrossScalaModule extends MillPublishJavaModule with CrossScalaModule
+
 object bridge extends Cross[BridgeModule](compilerBridgeScalaVersions)
-trait BridgeModule extends MillPublishJavaModule with CrossScalaModule {
+trait BridgeModule extends MillPublishCrossScalaModule {
   def scalaVersion = crossScalaVersion
   def publishVersion = bridgeVersion
   def artifactName = "mill-scala-compiler-bridge"

ci/mill-bootstrap.patch

@@ -1,5 +1,5 @@
 diff --git a/build.mill b/build.mill
-index 42be8622781..ecb84c31089 100644
+index 1f184f35cb7..c702f9e93a6 100644
 --- a/build.mill
 +++ b/build.mill
 @@ -1,16 +1,16 @@
@@ -23,7 +23,7 @@ index 42be8622781..ecb84c31089 100644
  import mill.T
  import mill.define.Cross
 
-@@ -288,19 +288,19 @@ object Deps {
+@@ -290,19 +290,19 @@ object Deps {
  }
 
  def millVersion: T[String] = Task.Input {
@@ -47,7 +47,7 @@ index 42be8622781..ecb84c31089 100644
  }
 
  def millDownloadPrefix = Task {
-@@ -319,7 +319,7 @@ def millBinPlatform: T[String] = Task {
+@@ -321,7 +321,7 @@ def millBinPlatform: T[String] = Task {
    }
  }
 
@@ -56,7 +56,7 @@ index 42be8622781..ecb84c31089 100644
 
  def millJvmVersion = Task.Source(Task.workspace / ".mill-jvm-version")
 
-@@ -469,7 +469,7 @@ trait MillPublishJavaModule extends MillJavaModule with PublishModule {
+@@ -471,7 +471,7 @@ trait MillPublishJavaModule extends MillJavaModule with PublishModule {
  /**
   * Some custom scala settings and test convenience
   */
@@ -65,7 +65,7 @@ index 42be8622781..ecb84c31089 100644
    def scalaVersion = Deps.scalaVersion
    def scalapVersion: T[String] = Deps.scala2Version
    def scalafixScalaBinaryVersion = T {
-@@ -526,8 +526,8 @@ trait MillScalaModule extends ScalaModule with MillJavaModule with ScalafixModul
+@@ -528,8 +528,8 @@ trait MillScalaModule extends ScalaModule with MillJavaModule with ScalafixModul
      val binaryVersion = ZincWorkerUtil.scalaBinaryVersion(sv)
      val hasModuleDefs = binaryVersion == "2.13" || binaryVersion == "3"
      super.scalacPluginIvyDeps() ++
@@ -76,7 +76,7 @@ index 42be8622781..ecb84c31089 100644
    }
 
    def mandatoryIvyDeps = T {
-@@ -535,13 +535,13 @@ trait MillScalaModule extends ScalaModule with MillJavaModule with ScalafixModul
+@@ -537,13 +537,13 @@ trait MillScalaModule extends ScalaModule with MillJavaModule with ScalafixModul
      val binaryVersion = ZincWorkerUtil.scalaBinaryVersion(sv)
      val hasModuleDefs = binaryVersion == "2.13" || binaryVersion == "3"
      super.mandatoryIvyDeps() ++
@@ -92,7 +92,7 @@ index 42be8622781..ecb84c31089 100644
      def scalafixConfig = T { Some(T.workspace / ".scalafix.conf") }
      def forkArgs = super.forkArgs() ++ outer.testArgs()
      def moduleDeps = outer.testModuleDeps
-@@ -581,7 +581,8 @@ trait MillBaseTestsModule extends TestModule {
+@@ -584,7 +584,8 @@ trait MillBaseTestsModule extends TestModule {
  trait MillPublishScalaModule extends MillScalaModule with MillPublishJavaModule
 
  /** Publishable module which contains strictly handled API. */
@@ -102,17 +102,17 @@ index 42be8622781..ecb84c31089 100644
    import com.github.lolgab.mill.mima._
    override def mimaBinaryIssueFilters: T[Seq[ProblemFilter]] = Seq(
      // (5x) MIMA doesn't properly ignore things which are nested inside other private things
-@@ -711,7 +712,7 @@ trait MillStableScalaModule extends MillPublishScalaModule with Mima {
+@@ -714,7 +715,7 @@ trait MillStableScalaModule extends MillPublishScalaModule with Mima {
    def skipPreviousVersions: T[Seq[String]] = T {
      T.log.info("Skipping mima for previous versions (!!1000s of errors due to Scala 3)")
      mimaPreviousVersions() // T(Seq.empty[String])
 -  }
 +  }*/
  }
 
- object bridge extends Cross[BridgeModule](compilerBridgeScalaVersions)
+ trait MillPublishCrossScalaModule extends MillPublishJavaModule with CrossScalaModule
 diff --git a/contrib/package.mill b/contrib/package.mill
-index 78dac75644b..fa53e9c7525 100644
+index b68c27a1ef8..01a3e9da2c0 100644
 --- a/contrib/package.mill
 +++ b/contrib/package.mill
 @@ -3,13 +3,12 @@ package build.contrib
@@ -189,7 +189,7 @@ index e49f218f4be..9d03aa073f3 100644
        def ivyDeps = Task {
          if (!caseName.contains("realistic") && !caseName.contains("sourcecode")) super.ivyDeps()
 diff --git a/dist/package.mill b/dist/package.mill
-index fbbeacbc843..b3e00f8db5f 100644
+index 515ed31025a..821d8fcc540 100644
 --- a/dist/package.mill
 +++ b/dist/package.mill
 @@ -2,15 +2,14 @@ package build.dist
@@ -219,7 +219,7 @@ index fbbeacbc843..b3e00f8db5f 100644
      PathRef(path)
    }
 
-@@ -185,10 +184,10 @@ object `package` extends RootModule with InstallModule {
+@@ -186,10 +185,10 @@ object `package` extends RootModule with InstallModule {
          val wd = os.Path(wd0, Task.workspace)
          os.makeDir.all(wd)
          try {
@@ -233,7 +233,7 @@ index fbbeacbc843..b3e00f8db5f 100644
            )
            mill.api.Result.Success(())
          } catch {
-@@ -233,7 +232,7 @@ object `package` extends RootModule with InstallModule {
+@@ -234,7 +233,7 @@ object `package` extends RootModule with InstallModule {
    def examplePathsWithArtifactName: Task[Seq[(os.Path, String)]] = Task.Anon {
      for {
        exampleMod <- build.example.exampleModules
@@ -242,15 +242,15 @@ index fbbeacbc843..b3e00f8db5f 100644
      } yield {
        val example = path.subRelativeTo(Task.workspace)
        val artifactName = example.segments.mkString("-")
-@@ -263,6 +262,7 @@ object `package` extends RootModule with InstallModule {
+@@ -264,6 +263,7 @@ object `package` extends RootModule with InstallModule {
    }
 
    def uploadToGithub(authKey: String) = Task.Command {
 +    /*
      val vcsState = VcsVersion.vcsState()
      val label = vcsState.copy(dirtyHash = None).format()
      if (label != build.millVersion()) sys.error("Modified mill version detected, aborting upload")
-@@ -279,7 +279,7 @@ object `package` extends RootModule with InstallModule {
+@@ -280,7 +280,7 @@ object `package` extends RootModule with InstallModule {
          headers = Seq("Authorization" -> ("token " + authKey))
        )
      }
@@ -259,7 +259,7 @@ index fbbeacbc843..b3e00f8db5f 100644
      ()
    }
 
-@@ -316,7 +316,7 @@ object `package` extends RootModule with InstallModule {
+@@ -317,7 +317,7 @@ object `package` extends RootModule with InstallModule {
          out.write(os.read.bytes(assembly().path))
        }
 
@@ -269,7 +269,7 @@ index fbbeacbc843..b3e00f8db5f 100644
        PathRef(executable)
      }
 diff --git a/example/package.mill b/example/package.mill
-index 62190fd6c1e..9d4f176c915 100644
+index fd3a934c8ff..56e35add240 100644
 --- a/example/package.mill
 +++ b/example/package.mill
 @@ -3,13 +3,12 @@ package build.example
@@ -287,7 +287,7 @@ index 62190fd6c1e..9d4f176c915 100644
  import mill.contrib.buildinfo.BuildInfo
  import mill.T
  import mill.define.Cross
-@@ -18,111 +17,111 @@ import mill.define.Cross
+@@ -18,112 +17,112 @@ import mill.define.Cross
  import $meta._
 
  object `package` extends RootModule with Module {
@@ -357,13 +357,15 @@ index 62190fd6c1e..9d4f176c915 100644
 -    object web extends Cross[ExampleCrossModule](build.listIn(millSourcePath / "web"))
 -    object native extends Cross[ExampleCrossModule](build.listIn(millSourcePath / "native"))
 -    object spark extends Cross[ExampleCrossModule](build.listIn(millSourcePath / "spark"))
+-    object migrating extends Cross[ExampleCrossModule](build.listIn(millSourcePath / "migrating"))
 +        extends Cross[ExampleCrossModule](build.listIn(moduleDir / "dependencies"))
 +    object testing extends Cross[ExampleCrossModule](build.listIn(moduleDir / "testing"))
 +    object linting extends Cross[ExampleCrossModule](build.listIn(moduleDir / "linting"))
 +    object publishing extends Cross[ExampleCrossModule](build.listIn(moduleDir / "publishing"))
 +    object web extends Cross[ExampleCrossModule](build.listIn(moduleDir / "web"))
 +    object native extends Cross[ExampleCrossModule](build.listIn(moduleDir / "native"))
 +    object spark extends Cross[ExampleCrossModule](build.listIn(moduleDir / "spark"))
++    object migrating extends Cross[ExampleCrossModule](build.listIn(moduleDir / "migrating"))
    }
    object javascriptlib extends Module {
 -    object basic extends Cross[ExampleCrossModule](build.listIn(millSourcePath / "basic"))
@@ -457,7 +459,7 @@ index 62190fd6c1e..9d4f176c915 100644
        case "1-test-suite" => line
            .replace(
              "mill bar.test bar.BarTests.hello",
-@@ -147,7 +146,7 @@ object `package` extends RootModule with Module {
+@@ -148,7 +147,7 @@ object `package` extends RootModule with Module {
        case "publishing" => Some(scalalib.publishing)
        case _ => None
      }
@@ -466,7 +468,7 @@ index 62190fd6c1e..9d4f176c915 100644
        .flatMap(_.valuesToModules.get(List(crossValue)))
 
      def testRepoRoot = Task {
-@@ -213,10 +212,10 @@ object `package` extends RootModule with Module {
+@@ -214,10 +213,10 @@ object `package` extends RootModule with Module {
 
    trait ExampleCrossModule extends build.integration.IntegrationTestModule {
      // disable scalafix because these example modules don't have sources causing it to misbehave
@@ -479,7 +481,7 @@ index 62190fd6c1e..9d4f176c915 100644
      def sources = Task {
        sources0()
          .flatMap(pathRef => os.walk(pathRef.path))
-@@ -245,7 +244,7 @@ object `package` extends RootModule with Module {
+@@ -246,7 +245,7 @@ object `package` extends RootModule with Module {
 
      def rendered = Task {
        var seenCode = false
@@ -488,7 +490,7 @@ index 62190fd6c1e..9d4f176c915 100644
        os.write(
          Task.dest / "example.adoc",
          parsed()
-@@ -303,7 +302,7 @@ $txt
+@@ -304,7 +303,7 @@ $txt
      "gatling" -> ("gatling/gatling", "3870fda86e6bca005fbd53108c60a65db36279b6"),
      "arrow" -> ("arrow-kt/arrow", "bc9bf92cc98e01c21bdd2bf8640cf7db0f97204a")
    )
@@ -498,7 +500,7 @@ index 62190fd6c1e..9d4f176c915 100644
      val (repoPath, repoHash) = repoInfo(crossValue)
      def repoSlug = repoPath.split("/").last
 diff --git a/integration/package.mill b/integration/package.mill
-index 53cdc15a9f6..9271663b81e 100644
+index 4b27b722fdb..8a1df6bf598 100644
 --- a/integration/package.mill
 +++ b/integration/package.mill
 @@ -3,13 +3,12 @@ package build.integration
@@ -600,7 +602,7 @@ index 957d929826d..112f1aaccb8 100644
      // TODO: document, why we have this dependency
      ivy"org.jsoup:jsoup:1.18.1"
 diff --git a/scalajslib/package.mill b/scalajslib/package.mill
-index 562041446af..f4cce7cebb1 100644
+index ee6663745f9..09b545ca7a5 100644
 --- a/scalajslib/package.mill
 +++ b/scalajslib/package.mill
 @@ -44,7 +44,7 @@ object `package` extends RootModule with build.MillStableScalaModule with BuildI
@@ -613,7 +615,7 @@ index 562041446af..f4cce7cebb1 100644
      def mandatoryIvyDeps = Agg.empty[Dep]
      def compileIvyDeps = super.mandatoryIvyDeps() ++ Agg(
 diff --git a/scalalib/package.mill b/scalalib/package.mill
-index d25adf2effd..6852f802156 100644
+index df9a8c206ba..aa7da099928 100644
 --- a/scalalib/package.mill
 +++ b/scalalib/package.mill
 @@ -2,14 +2,13 @@ package build.scalalib
@@ -659,7 +661,7 @@ index 3b577e29c65..7f45dcaeab6 100644
    def forkEnv =
      super.forkEnv() ++ Map("MILL_EXECUTABLE_PATH" -> build.dist.launcher().path.toString())
 diff --git a/website/package.mill b/website/package.mill
-index f88dc3fe8f6..2e2d2be3716 100644
+index 8c7cc0641db..52ab881d38c 100644
 --- a/website/package.mill
 +++ b/website/package.mill
 @@ -26,7 +26,7 @@ object `package` extends RootModule {

core/constants/src/mill/constants/Util.java

@@ -10,8 +10,12 @@
 
 public class Util {
 
-  public static boolean isWindows =
-      System.getProperty("os.name").toLowerCase(Locale.ROOT).startsWith("windows");
+  private static String lowerCaseOsName() {
+    return System.getProperty("os.name").toLowerCase(Locale.ROOT);
+  }
+
+  public static boolean isWindows = lowerCaseOsName().startsWith("windows");
+  public static boolean isLinux = lowerCaseOsName().equals("linux");
   public static boolean isJava9OrAbove =
       !System.getProperty("java.specification.version").startsWith("1.");
 

dist/package.mill

@@ -75,6 +75,7 @@ object `package` extends RootModule with InstallModule {
       build.main.graphviz.testDep(),
       build.main.init.maven.testDep(),
       build.main.init.gradle.testDep(),
+      build.main.init.sbt.testDep(),
       build.scalalib.backgroundwrapper.testDep(),
       build.contrib.bloop.testDep(),
       build.contrib.buildinfo.testDep(),

example/package.mill

@@ -64,6 +64,7 @@ object `package` extends RootModule with Module {
     object web extends Cross[ExampleCrossModule](build.listIn(millSourcePath / "web"))
     object native extends Cross[ExampleCrossModule](build.listIn(millSourcePath / "native"))
     object spark extends Cross[ExampleCrossModule](build.listIn(millSourcePath / "spark"))
+    object migrating extends Cross[ExampleCrossModule](build.listIn(millSourcePath / "migrating"))
   }
   object javascriptlib extends Module {
     object basic extends Cross[ExampleCrossModule](build.listIn(millSourcePath / "basic"))

example/scalalib/migrating/1-sbt-complete/build.mill

@@ -0,0 +1,28 @@
+/** Usage
+
+> rm build.mill # remove any existing build file
+
+> git init .
+> git remote add -f origin https://github.com/scala/scala3-example-project.git
+> git checkout 853808c50601e88edaa7272bcfb887b96be0e22a
+
+> ./mill init
+converting sbt build
+Running the added `millInitExportBuild` sbt task to export the build
+converting module scala3-example-project
+generated 1 Mill build file(s)
+removing existing Mill build files
+writing Mill build file to build.mill
+converted sbt build to Mill
+formatting Mill build files
+Formatting 1 Scala sources
+parsed config (v3.8.4): ...
+init completed, run "mill resolve _" to list available tasks
+
+> ./mill compile
+compiling 13 Scala sources to ...out/compile.dest/classes ...
+
+> ./mill test
+MySuite:
+  + example test that succeeds ...
+*/

example/scalalib/migrating/2-sbt-incomplete/build.mill

@@ -0,0 +1,27 @@
+/** Usage
+
+> rm build.mill # remove any existing build file
+
+> git init .
+> git remote add -f origin https://github.com/tototoshi/scala-csv.git
+> git checkout 2.0.0
+
+> ./mill init
+converting sbt build
+Running the added `millInitExportBuild` sbt task to export the build
+converting module scala-csv
+generated 1 Mill build file(s)
+removing existing Mill build files
+writing Mill build file to build.mill
+converted sbt build to Mill
+formatting Mill build files
+Formatting 1 Scala sources
+parsed config (v3.8.4): ...
+init completed, run "mill resolve _" to list available tasks
+
+> ./mill compile # You will have to further configure the `CrossScalaModule` for different Scala versions
+compiling 7 Scala sources and 3 Java sources to ...out/compile.dest/classes ...
+error: class CSVReader protected (private val lineReader: LineReader)(implicit format: CSVFormat) extends Closeable with CSVReaderCompat {
+error:                                                                                                                   ^
+error: one error found
+*/