add -sourceroot conditionally (it was introduced in Scala 3); change from --sourceroot to -sourceroot

Author: Blaine Freestone

src/main/scala/higherkindness/rules_scala/workers/zinc/compile/FilteredSetup.scala

@@ -4,23 +4,23 @@ import xsbti.compile.{CompileOptions, MiniSetup}
 import java.nio.file.{Path, Paths}
 
 /**
- * Zinc's MiniSetup contains scalacOptions which include the --sourceroot flag that references
+ * Zinc's MiniSetup contains scalacOptions which include the -sourceroot flag that references
  * absolute sandbox paths. These paths are non-deterministic across builds because the sandbox
  * directory changes (e.g., __sandbox/4/_main vs __sandbox/8/_main), making the analysis files
  * non-deterministic.
  *
- * This class filters out the --sourceroot option from the scalacOptions to ensure deterministic
+ * This class filters out the -sourceroot option from the scalacOptions to ensure deterministic
  * analysis files.
  *
  * TODO: Consider if there's a better way to handle this upstream in Zinc
  */
 object FilteredSetup {
-  private val sourcerootFlag = "--sourceroot"
+  private val sourcerootFlag = "-sourceroot"
 
   def getFilteredSetup(setup: MiniSetup): MiniSetup = {
     val options = setup.options()
 
-    // Filter out the --sourceroot option and its value
+    // Filter out the -sourceroot option and its value
     val filteredScalacOptions = {
       val originalOptions = options.scalacOptions()
       val filtered = scala.collection.mutable.ArrayBuffer[String]()

src/main/scala/higherkindness/rules_scala/workers/zinc/compile/ZincRunner.scala

@@ -212,18 +212,25 @@ object ZincRunner extends WorkerMain[ZincRunnerWorkerConfig] {
         isWorker,
       )
 
+    val shouldIncludeSourceRoot = !scalaInstance.actualVersion.startsWith("0.") &&
+      scalaInstance.actualVersion.startsWith("3")
+
+    val scalacOptions =
+      workRequest.plugins.view.map(p => s"-Xplugin:$p").toArray ++
+      workRequest.compilerOptions ++
+      workRequest.compilerOptionsReferencingPaths.toArray ++
+      (if (shouldIncludeSourceRoot)
+        Array("-sourceroot", task.workDir.toAbsolutePath().toString)
+      else
+        Array.empty[String])
+
     val compileOptions =
       CompileOptions.create
-        .withSources(sources.view.map(source => PlainVirtualFile(source.toAbsolutePath().normalize())).toArray)
-        .withClasspath((classesOutputDir +: deps.view.map(_.classpath)).map(path => PlainVirtualFile(path)).toArray)
-        .withClassesDirectory(classesOutputDir)
-        .withJavacOptions(workRequest.javaCompilerOptions)
-        .withScalacOptions(
-          workRequest.plugins.view.map(p => s"-Xplugin:$p").toArray ++
-            workRequest.compilerOptions ++
-            workRequest.compilerOptionsReferencingPaths.toArray ++
-            Array("--sourceroot", task.workDir.toAbsolutePath().toString)
-        )
+      .withSources(sources.view.map(source => PlainVirtualFile(source.toAbsolutePath().normalize())).toArray)
+      .withClasspath((classesOutputDir +: deps.view.map(_.classpath)).map(path => PlainVirtualFile(path)).toArray)
+      .withClassesDirectory(classesOutputDir)
+      .withJavacOptions(workRequest.javaCompilerOptions)
+      .withScalacOptions(scalacOptions)
 
     val compilers = {
       val scalaCompiler = ZincUtil