Test Scala 3 input/output with rule built against Scala 2.12

.scalafmt.conf

@@ -1,7 +1,8 @@
+version = 2.7.5
 project.git = true
 assumeStandardLibraryStripMargin = true
 project.excludeFilters = [
-  "main/g8"
+  "main/g8/.*/.*\\.scala"
   "output/src"
   "migration-rules/*"
 ]

build.sbt

@@ -7,9 +7,12 @@ lazy val root = (project in file("."))
       val _ = (Test / g8Test).toTask("").value
       val s = streams.value
       s.log.info(
-        "running our own sbt in the copied directory to mimic the scripted test")
-      val p = Process(Seq("sbt", "tests/test"),
-                      (Test / g8 / target).value / "scalafix").run()
+        "running our own sbt in the copied directory to mimic the scripted test"
+      )
+      val p = Process(
+        Seq("sbt", "tests/test"),
+        (Test / g8 / target).value / "scalafix"
+      ).run()
       assert(p.exitValue() == 0, "Non-zero exit from sbt tests/test")
     },
     scriptedLaunchOpts ++= List(

migration-rules/v0.6.x/rules/src/main/scala/fix/Scalafixg8_v0_6.scala

@@ -50,19 +50,26 @@ class Scalafixg8_v0_6 extends SyntacticRule("Scalafixg8_v0_6") {
     doc.tree.traverse {
       case Init(rule @ Type.Name("Rule"), _, List(List(Lit.String(_)))) =>
         patch += Patch.replaceTree(rule, "SyntacticRule")
-      case init @ Init(Type.Name("SemanticRule"),
-                       _,
-                       List(List(Term.Name("index"), Lit.String(ruleName)))) =>
+      case init @ Init(
+            Type.Name("SemanticRule"),
+            _,
+            List(List(Term.Name("index"), Lit.String(ruleName)))
+          ) =>
         patch += Patch.replaceTree(init, s"""SemanticRule("$ruleName")""")
       case Ctor.Primary(
-          _,
-          _,
-          List(
+            _,
+            _,
             List(
-              param @ Term.Param(Nil,
-                                 Term.Name("index"),
-                                 Some(Type.Name("SemanticdbIndex")),
-                                 _)))) =>
+              List(
+                param @ Term.Param(
+                  Nil,
+                  Term.Name("index"),
+                  Some(Type.Name("SemanticdbIndex")),
+                  _
+                )
+              )
+            )
+          ) =>
         patch += Patch.removeTokens(param.tokens)
       case defn @ Defn.Def(
             _,
@@ -75,7 +82,8 @@ class Scalafixg8_v0_6 extends SyntacticRule("Scalafixg8_v0_6") {
                   ctx @ Term.Name("ctx"),
                   Some(ruleCtx @ Type.Name("RuleCtx")),
                   None
-                ))
+                )
+              )
             ),
             Some(Type.Name("Patch")),
             _
@@ -151,11 +159,15 @@ class Scalafixg8_v0_6 extends SyntacticRule("Scalafixg8_v0_6") {
         )
       case Importer(ref, importees) =>
         val syntax = ref.syntax
-        if (syntax.startsWith("scala.meta.contrib") ||
-            syntax.startsWith("scalafix.syntax")) {
+        if (
+          syntax.startsWith("scala.meta.contrib") ||
+          syntax.startsWith("scalafix.syntax")
+        ) {
           // do nothing
-        } else if (syntax.startsWith("org.langmeta.") ||
-                   syntax.startsWith("scala.meta.")) {
+        } else if (
+          syntax.startsWith("org.langmeta.") ||
+          syntax.startsWith("scala.meta.")
+        ) {
           addImporter(importer"scala.meta._", importees)
         } else if (syntax.startsWith("scalafix")) {
           addImporter(importer"scalafix.v1._", importees)

migration-rules/v0.9.28/rules/src/main/scala/fix/v0_9_28.scala

@@ -11,7 +11,8 @@ class v0_9_28 extends SemanticRule("v0_9_28") {
       case t @ Importee.Name(Name("SemanticRuleSuite")) =>
         Patch.removeImportee(t) +
           Patch.addGlobalImport(
-            importer"scalafix.testkit.AbstractSemanticRuleSuite")
+            importer"scalafix.testkit.AbstractSemanticRuleSuite"
+          )
       case t @ init"SemanticRuleSuite(..$_)" =>
         Patch.addGlobalImport(importer"org.scalatest.FunSuiteLike") +
           Patch.replaceTree(t, "AbstractSemanticRuleSuite with FunSuiteLike")

src/main/g8/default.properties

@@ -1,3 +1,2 @@
-repo = My Repo
-scalameta_version = maven(org.scalameta, scalameta_2.13)
-scalafix_version = maven(ch.epfl.scala, sbt-scalafix)
+repo = scalafix-my-rules
+scalafix_version = 0.9.28

src/main/g8/scalafix/build.sbt

@@ -1,11 +1,15 @@
 lazy val V = _root_.scalafix.sbt.BuildInfo
+
+lazy val rulesCrossVersions = Seq(V.scala213, V.scala212, V.scala211)
+lazy val scala3Version = "3.0.0"
+
 inThisBuild(
   List(
-    scalaVersion := V.scala213,
-    crossScalaVersions := List(V.scala213, V.scala212, V.scala211),
     organization := "com.example",
     homepage := Some(url("https://github.com/com/example")),
-    licenses := List("Apache-2.0" -> url("http://www.apache.org/licenses/LICENSE-2.0")),
+    licenses := List(
+      "Apache-2.0" -> url("http://www.apache.org/licenses/LICENSE-2.0")
+    ),
     developers := List(
       Developer(
         "example-username",
@@ -14,41 +18,88 @@ inThisBuild(
         url("https://example.com")
       )
     ),
-    addCompilerPlugin(scalafixSemanticdb),
-    scalacOptions ++= List(
-      "-Yrangepos",
-      "-P:semanticdb:synthetics:on"
-    )
+    semanticdbEnabled := true,
+    semanticdbVersion := scalafixSemanticdb.revision
   )
 )
 
-publish / skip := true
+lazy val `$repo;format="normalize"$` = (project in file("."))
+  .aggregate(
+    rules.projectRefs ++
+      input.projectRefs ++
+      output.projectRefs ++
+      tests.projectRefs: _*
+  )
+  .settings(
+    publish / skip := true
+  )
 
-lazy val rules = project.settings(
-  moduleName := "scalafix",
-  libraryDependencies += "ch.epfl.scala" %% "scalafix-core" % V.scalafixVersion
-)
+lazy val rules = projectMatrix
+  .settings(
+    moduleName := "scalafix",
+    libraryDependencies += "ch.epfl.scala" %% "scalafix-core" % V.scalafixVersion
+  )
+  .defaultAxes(VirtualAxis.jvm)
+  .jvmPlatform(rulesCrossVersions)
 
-lazy val input = project.settings(
-  publish / skip := true
-)
+lazy val input = projectMatrix
+  .settings(
+    publish / skip := true
+  )
+  .defaultAxes(VirtualAxis.jvm)
+  .jvmPlatform(scalaVersions = rulesCrossVersions :+ scala3Version)
 
-lazy val output = project.settings(
-  publish / skip := true
-)
+lazy val output = projectMatrix
+  .settings(
+    publish / skip := true
+  )
+  .defaultAxes(VirtualAxis.jvm)
+  .jvmPlatform(scalaVersions = rulesCrossVersions :+ scala3Version)
+
+lazy val testsAggregate = Project("tests", file("target/testsAggregate"))
+  .aggregate(tests.projectRefs: _*)
 
-lazy val tests = project
+lazy val tests = projectMatrix
   .settings(
     publish / skip := true,
     libraryDependencies += "ch.epfl.scala" % "scalafix-testkit" % V.scalafixVersion % Test cross CrossVersion.full,
-    Compile / compile :=
-      (Compile / compile).dependsOn(input / Compile / compile).value,
     scalafixTestkitOutputSourceDirectories :=
-      (output / Compile / unmanagedSourceDirectories).value,
+      TargetAxis
+        .resolve(output, Compile / unmanagedSourceDirectories)
+        .value,
     scalafixTestkitInputSourceDirectories :=
-      (input / Compile / unmanagedSourceDirectories).value,
+      TargetAxis
+        .resolve(input, Compile / unmanagedSourceDirectories)
+        .value,
     scalafixTestkitInputClasspath :=
-      (input / Compile / fullClasspath).value,
+      TargetAxis.resolve(input, Compile / fullClasspath).value,
+    scalafixTestkitInputScalacOptions :=
+      TargetAxis.resolve(input, Compile / scalacOptions).value,
+    scalafixTestkitInputScalaVersion :=
+      TargetAxis.resolve(input, Compile / scalaVersion).value
+  )
+  .defaultAxes(
+    rulesCrossVersions.map(VirtualAxis.scalaABIVersion) :+ VirtualAxis.jvm: _*
+  )
+  .customRow(
+    scalaVersions = Seq(V.scala212),
+    axisValues = Seq(TargetAxis(scala3Version), VirtualAxis.jvm),
+    settings = Seq()
+  )
+  .customRow(
+    scalaVersions = Seq(V.scala213),
+    axisValues = Seq(TargetAxis(V.scala213), VirtualAxis.jvm),
+    settings = Seq()
+  )
+  .customRow(
+    scalaVersions = Seq(V.scala212),
+    axisValues = Seq(TargetAxis(V.scala212), VirtualAxis.jvm),
+    settings = Seq()
+  )
+  .customRow(
+    scalaVersions = Seq(V.scala211),
+    axisValues = Seq(TargetAxis(V.scala211), VirtualAxis.jvm),
+    settings = Seq()
   )
   .dependsOn(rules)
   .enablePlugins(ScalafixTestkitPlugin)

src/main/g8/scalafix/input/src/main/scala-3/fix/$repo__Camel$SignificantIndentation.scala

@@ -0,0 +1,8 @@
+/*
+rule = $repo;format="Camel"$
+*/
+package fix
+
+object $repo;format="Camel"$SignificantIndentation:
+  val a = 1
+  // Add code that needs fixing here.

src/main/g8/scalafix/output/src/main/scala-3/fix/$repo__Camel$SignificantIndentation.scala

@@ -0,0 +1,5 @@
+package fix
+
+object $repo;format="Camel"$SignificantIndentation:
+  val a = 1
+  // Add code that needs fixing here.

src/main/g8/scalafix/project/TargetAxis.scala

@@ -0,0 +1,47 @@
+import sbt._
+import sbt.internal.ProjectMatrix
+import sbtprojectmatrix.ProjectMatrixPlugin.autoImport._
+
+/** Use on ProjectMatrix rows to tag an affinity to a custom scalaVersion */
+case class TargetAxis(scalaVersion: String) extends VirtualAxis.WeakAxis {
+
+  private val scalaBinaryVersion = CrossVersion.binaryScalaVersion(scalaVersion)
+
+  override val idSuffix = s"Target\${scalaBinaryVersion.replace('.', '_')}"
+  override val directorySuffix = s"target\$scalaBinaryVersion"
+}
+
+object TargetAxis {
+
+  private def targetScalaVersion(virtualAxes: Seq[VirtualAxis]): String =
+    virtualAxes.collectFirst { case a: TargetAxis => a.scalaVersion }.get
+
+  /** When invoked on a ProjectMatrix with a TargetAxis, lookup the project
+    * generated by `matrix` with a scalaVersion matching the one declared in
+    * that TargetAxis, and resolve `key`.
+    */
+  def resolve[T](
+      matrix: ProjectMatrix,
+      key: TaskKey[T]
+  ): Def.Initialize[Task[T]] =
+    Def.taskDyn {
+      val sv = targetScalaVersion(virtualAxes.value)
+      val project = matrix.finder().apply(sv)
+      Def.task((project / key).value)
+    }
+
+  /** When invoked on a ProjectMatrix with a TargetAxis, lookup the project
+    * generated by `matrix` with a scalaVersion matching the one declared in
+    * that TargetAxis, and resolve `key`.
+    */
+  def resolve[T](
+      matrix: ProjectMatrix,
+      key: SettingKey[T]
+  ): Def.Initialize[T] =
+    Def.settingDyn {
+      val sv = targetScalaVersion(virtualAxes.value)
+      val project = matrix.finder().apply(sv)
+      Def.setting((project / key).value)
+    }
+
+}

src/main/g8/scalafix/project/plugins.sbt

@@ -1,2 +1,3 @@
 resolvers += Resolver.sonatypeRepo("releases")
 addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "$scalafix_version$")
+addSbtPlugin("com.eed3si9n" % "sbt-projectmatrix" % "0.8.0")