support parsing scala 2.13.6 -Xsource:3 dialect

src/main/scala/scalafix/sbt/ScalafixPlugin.scala

@@ -380,6 +380,7 @@ object ScalafixPlugin extends AutoPlugin {
             Arg.Config(scalafixConf),
             Arg.Rules(shell.rules),
             Arg.ScalaVersion(scalaVersion.value),
+            Arg.ScalacOptions(scalacOptions.in(config, compile).value),
             Arg.ParsedArgs(shell.extra)
           )
         val rulesThatWillRun = mainInterface.rulesThatWillRun()
@@ -427,17 +428,16 @@ object ScalafixPlugin extends AutoPlugin {
       val dependencies = allDependencies.in(config).value
       val files = filesToFix(shellArgs, config).value
       val scalacOpts = scalacOptions.in(config, compile).value
-      val withScalaInterface = mainArgs.withArgs(Arg.ScalacOptions(scalacOpts))
       val errors = new SemanticRuleValidator(
         new SemanticdbNotFound(ruleNames, scalaVersion.value)
-      ).findErrors(files, dependencies, scalacOpts, withScalaInterface)
+      ).findErrors(files, dependencies, scalacOpts, mainArgs)
       if (errors.isEmpty) {
         val task = Def.task {
           // don't use fullClasspath as it results in a cyclic dependency via compile when scalafixOnCompile := true
           val classpath =
             dependencyClasspath.in(config).value.map(_.data.toPath) :+
               classDirectory.in(config).value.toPath
-          val semanticInterface = withScalaInterface.withArgs(
+          val semanticInterface = mainArgs.withArgs(
             Arg.Paths(files),
             Arg.Classpath(classpath)
           )

src/sbt-test/sbt-1.5/testkit/build.sbt

@@ -62,7 +62,9 @@ lazy val tests = projectMatrix
   .customRow(
     scalaVersions = Seq(V.scala213),
     axisValues = Seq(InputAxis(V.scala213), VirtualAxis.jvm),
-    settings = Seq()
+    settings = Seq(
+      scalacOptions += "-Xsource:3"
+    )
   )
   .customRow(
     scalaVersions = Seq(V.scala212),

src/sbt-test/sbt-1.5/testkit/input/src/main/scala-2.13.6/fix/Source3.scala

@@ -0,0 +1,6 @@
+/*
+rules = [ SemanticRule ]
+ */
+package fix
+
+open class Source3

src/sbt-test/sbt-1.5/testkit/output/src/main/scala-2.13.6/fix/Source3.scala

@@ -0,0 +1,3 @@
+package fix
+
+open class Source3

src/sbt-test/sbt-1.5/testkit/test

@@ -1,3 +1,3 @@
 -> tests/test
-> testsInput3/test:run --save-expect
+> testsInput2_13/test:run --save-expect
 > tests/test

src/sbt-test/sbt-scalafix/cross-build/213.scalafix.conf

@@ -0,0 +1,3 @@
+rules = [
+  ProcedureSyntax
+]

src/sbt-test/sbt-scalafix/cross-build/build.sbt

@@ -18,7 +18,8 @@ lazy val root = project
     javaProject,
     scala211,
     scala210,
-    scala212
+    scala212,
+    scala213
   )
 
 lazy val scala210 = project.settings(
@@ -42,6 +43,15 @@ lazy val scala212 = project
   )
   .settings(scalafixConfigSettings(IntegrationTest): _*)
 
+lazy val scala213 = project.settings(
+  scalaVersion := Versions.scala213,
+  scalacOptions += "-Xsource:3",
+  scalafixSettings,
+  // NoAutoTupling is not supported
+  scalacOptions -= "-Ywarn-adapted-args",
+  scalafixConfig := Some(file("213.scalafix.conf"))
+)
+
 lazy val javaProject = project.settings(
   scalaVersion := Versions.scala212,
   scalafixSettings

src/sbt-test/sbt-scalafix/cross-build/scala213/src/main/scala/Source3.scala

@@ -0,0 +1 @@
+open class Source3