add scalafix-loader with support for version in .scalafix.conf

Add implementation of Scalafix & ScalafixArguments in new project, with
support for targeting a different scalafix-cli version, based on an optional
scalafix version in .scalafix.conf. That scalafix-cli version is fetched and
loaded via service provider when one of the non-with method is invoked, and
initialized with all accumulated parameters.

Author: bjaglin

CONTRIBUTING.md

@@ -19,6 +19,8 @@ hesitate to ask in the [Discord channel](https://discord.gg/8AHaqGx3Qj).
 
 ### For tool integration
 - `scalafix-interfaces/` Java facade to run rules within an existing JVM instance.
+- `scalafix-loader/` Java implementation to dynamically fetch and load
+  implementations to run rules.
 - `scalafix-versions/` Java implementation to advertize which Scala versions
   `scalafix-cli` is published with.
 

build.sbt

@@ -51,6 +51,25 @@ lazy val versions = project
   .disablePlugins(ScalafixPlugin)
   .dependsOn(interfaces)
 
+lazy val loader = project
+  .in(file("scalafix-loader"))
+  .settings(
+    moduleName := "scalafix-loader",
+    javaSettings,
+    mimaPreviousArtifacts := Set.empty, // TODO: remove after 0.14.4
+    libraryDependencies ++= Seq(
+      typesafeConfig,
+      lombok % Provided
+    ),
+    javacOptions ++= {
+      // https://inside.java/2024/06/18/quality-heads-up/
+      if (jdk > 8) Seq("-proc:full")
+      else Seq() // only backported to Oracle’s 8u release (8u411)
+    }
+  )
+  .disablePlugins(ScalafixPlugin)
+  .dependsOn(interfaces, versions)
+
 // Scala 3 macros vendored separately (i.e. without runtime classes), to
 // shadow Scala 2.13 macros in the Scala 3 compiler classpath, while producing
 // code valid against Scala 2.13 bytecode
@@ -346,18 +365,9 @@ lazy val integration = projectMatrix
       "inputSourceroot" ->
         resolve(input, Compile / sourceDirectory).value,
       "outputSourceroot" ->
-        resolve(output, Compile / sourceDirectory).value,
-      "versionsJars" ->
-        Seq(
-          (interfaces / Compile / packageBin / artifactPath).value,
-          (versions / Compile / packageBin / artifactPath).value
-        )
+        resolve(output, Compile / sourceDirectory).value
     ),
     Test / test := (Test / test)
-      .dependsOn(
-        interfaces / Compile / packageBin,
-        versions / Compile / packageBin
-      )
       .dependsOn(resolve(cli, publishLocalTransitive))
       .dependsOn(
         cli.projectRefs
@@ -368,22 +378,18 @@ lazy val integration = projectMatrix
       .value,
     Test / testWindows := (Test / testWindows)
       .dependsOn(
-        interfaces / Compile / packageBin,
-        versions / Compile / packageBin
-      )
-      .dependsOn(resolve(cli, publishLocalTransitive))
-      .dependsOn(
-        cli.projectRefs
+        (resolve(cli, publishLocalTransitive) +: cli.projectRefs
           // always publish Scala 3 artifacts to test Scala 3 minor version fallbacks
           .collect { case p @ LocalProject(n) if n.startsWith("cli3") => p }
-          .map(_ / publishLocalTransitive): _*
+          .map(_ / publishLocalTransitive)): _*
       )
       .value
   )
   .defaultAxes(VirtualAxis.jvm)
   .jvmPlatform(CrossVersion.full, cliScalaVersions)
   .enablePlugins(BuildInfoPlugin)
   .dependsOn(unit % "compile->test")
+  .dependsOn(loader % "compile->test")
 
 lazy val expect = projectMatrix
   .in(file("scalafix-tests/expect"))

project/Dependencies.scala

@@ -21,13 +21,15 @@ object Dependencies {
   val commontTextV = "1.13.1"
   val googleDiffV = "1.3.0"
   val jgitV = "5.13.3.202401111512-r"
+  val lombokV = "1.18.38"
   val metaconfigV = "0.15.0"
   val nailgunV = "0.9.1"
   val scalaXmlV = "2.2.0"
   val scalametaV = "4.13.5"
   val scalatagsV = "0.13.1"
   val scalatestV = "3.2.19"
   val munitV = "1.1.0"
+  val typesafeConfigV = "1.4.3"
 
   val bijectionCore = "com.twitter" %% "bijection-core" % bijectionCoreV
   val collectionCompat = "org.scala-lang.modules" %% "scala-collection-compat" % collectionCompatV
@@ -36,6 +38,7 @@ object Dependencies {
   val coursierInterfaces = "io.get-coursier" % "interface" % coursierInterfaceV
   val googleDiff = "com.googlecode.java-diff-utils" % "diffutils" % googleDiffV
   val jgit = "org.eclipse.jgit" % "org.eclipse.jgit" % jgitV
+  val lombok = "org.projectlombok" % "lombok" % lombokV
   val metaconfig = "org.scalameta" %% "metaconfig-typesafe-config" % metaconfigV
   val metacp = "org.scalameta" %% "metacp" % scalametaV
   val nailgunServer = "com.martiansoftware" % "nailgun-server" % nailgunV
@@ -47,6 +50,7 @@ object Dependencies {
   val munit = "org.scalameta" %% "munit" % munitV
   val semanticdbScalacCore = "org.scalameta" % "semanticdb-scalac-core" % scalametaV cross CrossVersion.full
   val semanticdbSharedFor3Use2_13 = "org.scalameta" % "semanticdb-shared" % scalametaV cross CrossVersion.for3Use2_13
+  val typesafeConfig = "com.typesafe" % "config" % typesafeConfigV
 
   // scala-steward:off
 

project/Mima.scala

@@ -7,8 +7,11 @@ object Mima {
     // See https://github.com/lightbend/mima
     Seq(
       ProblemFilters.exclude[Problem]("scalafix.internal.*"),
-      ProblemFilters.exclude[Problem]("scala.meta.internal.*")
+      ProblemFilters.exclude[Problem]("scala.meta.internal.*"),
       // Exceptions
+      ProblemFilters.exclude[ReversedMissingMethodProblem]("scalafix.interfaces.ScalafixArguments.withRepositories"),
+      ProblemFilters.exclude[ReversedMissingMethodProblem]("scalafix.interfaces.ScalafixArguments.withToolDependencyCoordinates"),
+      ProblemFilters.exclude[ReversedMissingMethodProblem]("scalafix.interfaces.ScalafixArguments.withToolDependencyURLs")
     )
   }
 }

project/ScalafixBuild.scala

@@ -41,10 +41,11 @@ object ScalafixBuild extends AutoPlugin with GhpagesKeys {
       autoScalaLibrary := false
     )
 
+    lazy val jdk = System.getProperty("java.specification.version").toDouble
+
     // https://github.com/scalameta/scalameta/issues/2485
     lazy val coreScalaVersions = Seq(scala212, scala213)
     lazy val cliScalaVersions = {
-      val jdk = System.getProperty("java.specification.version").toDouble
       val scala3Versions =
         // Scala 3.5 will never support JDK 23
         if (jdk >= 23) Seq(scala33, scala36, scala37)

scalafix-cli/src/main/resources/META-INF/services/scalafix.interfaces.ScalafixArguments

@@ -0,0 +1 @@
+scalafix.internal.interfaces.ScalafixArgumentsImpl

scalafix-cli/src/main/scala/scalafix/internal/interfaces/ScalafixArgumentsImpl.scala

@@ -34,6 +34,8 @@ import scalafix.v1.RuleDecoder
 final case class ScalafixArgumentsImpl(args: Args = Args.default)
     extends ScalafixArguments {
 
+  def this() = this(Args.default)
+
   override def run(): Array[ScalafixError] = {
     val exit = MainOps.run(Array(), args)
     ScalafixErrorImpl.fromScala(exit)
@@ -48,39 +50,44 @@ final case class ScalafixArgumentsImpl(args: Args = Args.default)
     }
   }
 
+  override def withRepositories(
+      repositories: util.List[Repository]
+  ): ScalafixArguments =
+    copy(args = args.copy(repositories = repositories.asScala.toList))
+
   override def withRules(rules: util.List[String]): ScalafixArguments =
     copy(args = args.copy(rules = rules.asScala.toList))
 
   override def withToolClasspath(
       customURLs: util.List[URL]
   ): ScalafixArguments =
-    withToolClasspath(
-      customURLs,
-      Nil.asJava,
-      Repository.defaults()
-    )
+    withToolDependencyURLs(customURLs)
 
   override def withToolClasspath(
       customURLs: util.List[URL],
       customDependenciesCoordinates: util.List[String]
   ): ScalafixArguments =
-    withToolClasspath(
-      customURLs,
-      customDependenciesCoordinates,
-      Repository.defaults()
-    )
+    withToolDependencyCoordinates(customDependenciesCoordinates)
+      .withToolDependencyURLs(customURLs)
 
   override def withToolClasspath(
       customURLs: util.List[URL],
       customDependenciesCoordinates: util.List[String],
       repositories: util.List[Repository]
   ): ScalafixArguments = {
+    withRepositories(repositories)
+      .withToolDependencyCoordinates(customDependenciesCoordinates)
+      .withToolDependencyURLs(customURLs)
+  }
 
+  override def withToolDependencyCoordinates(
+      withToolDependencyCoordinates: java.util.List[String]
+  ): ScalafixArguments = {
     val OrganizeImportsCoordinates =
       """com\.github\.liancheng.*:organize-imports:.*""".r
 
     val keptDependencies: Seq[String] =
-      customDependenciesCoordinates.asScala
+      withToolDependencyCoordinates.asScala
         .collect {
           case dep @ OrganizeImportsCoordinates() =>
             args.out.println(
@@ -107,7 +114,7 @@ final case class ScalafixArgumentsImpl(args: Args = Args.default)
       else Versions.scalaVersion
 
     val customDependenciesJARs = ScalafixCoursier.toolClasspath(
-      repositories,
+      args.repositories.asJava,
       keptDependencies.asJava,
       scalaVersionForDependencies
     )
@@ -158,13 +165,23 @@ final case class ScalafixArgumentsImpl(args: Args = Args.default)
         }
       }
 
-    val extraURLs = customURLs.asScala ++ customDependenciesJARs
+    val extraURLs = customDependenciesJARs
       .getFiles()
       .asScala
       .map(_.toURI().toURL())
     val classLoader = new URLClassLoader(
       extraURLs.toArray,
-      getClass.getClassLoader
+      args.toolClasspath
+    )
+    withToolClasspath(classLoader)
+  }
+
+  override def withToolDependencyURLs(
+      withToolDependencyURLs: java.util.List[java.net.URL]
+  ): ScalafixArguments = {
+    val classLoader = new URLClassLoader(
+      withToolDependencyURLs.asScala.toArray,
+      args.toolClasspath
     )
     withToolClasspath(classLoader)
   }

scalafix-cli/src/main/scala/scalafix/internal/v1/Args.scala

@@ -13,6 +13,7 @@ import java.util.regex.Pattern
 import java.util.regex.PatternSyntaxException
 
 import scala.annotation.StaticAnnotation
+import scala.jdk.CollectionConverters._
 import scala.util.Failure
 import scala.util.Success
 import scala.util.Try
@@ -22,6 +23,8 @@ import scala.meta.internal.symtab.SymbolTable
 import scala.meta.io.AbsolutePath
 import scala.meta.io.Classpath
 
+import coursierapi.MavenRepository
+import coursierapi.Repository
 import metaconfig.Configured._
 import metaconfig._
 import metaconfig.annotation._
@@ -158,6 +161,8 @@ case class Args(
         "The glob syntax is defined by `nio.FileSystem.getPathMatcher`."
     )
     exclude: List[PathMatcher] = Nil,
+    @Description("Maven repositories to fetch the artifacts from")
+    repositories: List[Repository] = Repository.defaults.asScala.toList,
     @Description(
       "Additional classpath for compiling and classloading custom rules, as a set of filesystem paths, separated by ':' on Unix or ';' on Windows."
     )
@@ -483,6 +488,8 @@ object Args extends TPrintImplicits {
     ConfDecoder.stringConfDecoder.map(glob =>
       FileSystems.getDefault.getPathMatcher("glob:" + glob)
     )
+  implicit val repositoryDecoder: ConfDecoder[Repository] =
+    ConfDecoder.stringConfDecoder.map(base => MavenRepository.of(base))
   implicit val scalaVersionDecoder: ConfDecoder[ScalaVersion] =
     ScalafixConfig.scalaVersionDecoder
 
@@ -505,6 +512,8 @@ object Args extends TPrintImplicits {
     ConfEncoder.StringEncoder.contramap(_ => "<stdout>")
   implicit val pathMatcherEncoder: ConfEncoder[PathMatcher] =
     ConfEncoder.StringEncoder.contramap(_.toString)
+  implicit val repositoriesEncoder: ConfEncoder[Repository] =
+    ConfEncoder.StringEncoder.contramap(_.toString)
   implicit val callbackEncoder: ConfEncoder[ScalafixMainCallback] =
     ConfEncoder.StringEncoder.contramap(_.toString)
   implicit val argsEncoder: ConfEncoder[Args] = generic.deriveEncoder