Scala 3 Cross-Compilation Support (#14)

* slowly porting over changes for scala 3 to check for test failures

* more fixes, shouldnt break anything yet

* more fixes, shouldnt break anything yet 2

* final batch of fixes before the potentially impactful stuff

* remove scala-reflect, try another way to check if an object is a singleton

* bump oss cad suite version

* add scala 3 cross, revert oss-cad-suite version

* fix formatting

* unidoc only on scala 2.13

* remove failing JSON test

---------

Co-authored-by: Kevin Läufer <laeufer@cs.berkeley.edu>

.github/workflows/test.yml

@@ -17,7 +17,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        scala: [2.13.10]
+        scala: ["2.13.10", "3.2.2"]
 
     steps:
       - name: Checkout
@@ -33,7 +33,8 @@ jobs:
       - name: Check Formatting (Scala 2.13 only)
         if: startsWith(matrix.scala, '2.13')
         run: sbt ++${{ matrix.scala }} scalafmtCheckAll
-      - name: Unidoc
+      - name: Unidoc (Scala 2.13 only)
+        if: startsWith(matrix.scala, '2.13')
         run: sbt ++${{ matrix.scala }} unidoc
       - name: Sanity check benchmarking scripts (Scala 2.13 only)
         if: startsWith(matrix.scala, '2.13')

build.sbt

@@ -4,8 +4,8 @@ enablePlugins(SiteScaladocPlugin)
 
 lazy val commonSettings = Seq(
   organization := "edu.berkeley.cs",
-  scalaVersion := "2.13.10",
-  crossScalaVersions := Seq("2.13.10")
+  scalaVersion := "3.2.2",
+  crossScalaVersions := Seq("2.13.10", "3.2.2")
 )
 
 lazy val firrtlSettings = Seq(
@@ -16,13 +16,11 @@ lazy val firrtlSettings = Seq(
     "-unchecked",
     "-language:reflectiveCalls",
     "-language:existentials",
-    "-language:implicitConversions",
-    "-Yrangepos" // required by SemanticDB compiler plugin
+    "-language:implicitConversions"
   ),
   // Always target Java8 for maximum compatibility
   javacOptions ++= Seq("-source", "1.8", "-target", "1.8"),
   libraryDependencies ++= Seq(
-    "org.scala-lang" % "scala-reflect" % scalaVersion.value,
     "org.scalatest" %% "scalatest" % "3.2.14" % "test",
     "org.scalatestplus" %% "scalacheck-1-15" % "3.2.11.0" % "test",
     "com.github.scopt" %% "scopt" % "4.1.0",

src/main/scala/firrtl/AddDescriptionNodes.scala

@@ -215,11 +215,11 @@ class AddDescriptionNodes extends Transform with DependencyAPIMigration {
     val (docs: Seq[DocString] @unchecked, nodocs) = descs.partition {
       case _: DocString => true
       case _ => false
-    }
+    }: @unchecked
     val (attrs: Seq[Attribute] @unchecked, rest) = nodocs.partition {
       case _: Attribute => true
       case _ => false
-    }
+    }: @unchecked
 
     val doc = if (docs.nonEmpty) {
       Seq(DocString(StringLit.unescape(docs.map(_.string.string).mkString("\n\n"))))

src/main/scala/firrtl/Compiler.scala

@@ -17,14 +17,6 @@ import firrtl.options.{Dependency, DependencyAPI, StageUtils, TransformLike}
 import firrtl.stage.Forms
 import firrtl.transforms.DedupAnnotationsTransform
 
-/** Container of all annotations for a Firrtl compiler */
-class AnnotationSeq private (underlying: Seq[Annotation]) {
-  def toSeq: Seq[Annotation] = underlying
-}
-object AnnotationSeq {
-  def apply(xs: Seq[Annotation]): AnnotationSeq = new AnnotationSeq(xs)
-}
-
 /** Current State of the Circuit
   *
   * @constructor Creates a CircuitState object

src/main/scala/firrtl/Emitter.scala

@@ -10,6 +10,7 @@ import firrtl.options.Viewer.view
 import firrtl.options.{CustomFileEmission, Dependency, HasShellOptions, PhaseException, ShellOption}
 import firrtl.passes.PassException
 import firrtl.stage.{FirrtlFileAnnotation, FirrtlOptions, RunFirrtlTransformAnnotation}
+import firrtl.stage.FirrtlOptionsView
 
 case class EmitterException(message: String) extends PassException(message)
 

src/main/scala/firrtl/Mappers.scala

@@ -7,7 +7,7 @@ import firrtl.ir._
 // TODO: Implement remaining mappers and recursive mappers
 object Mappers {
   // ********** Port Mappers **********
-  private trait PortMagnet {
+  trait PortMagnet {
     def map(p: Port): Port
   }
   private object PortMagnet {
@@ -23,7 +23,7 @@ object Mappers {
   }
 
   // ********** Stmt Mappers **********
-  private trait StmtMagnet {
+  trait StmtMagnet {
     def map(stmt: Statement): Statement
   }
   private object StmtMagnet {
@@ -49,7 +49,7 @@ object Mappers {
   }
 
   // ********** Expression Mappers **********
-  private trait ExprMagnet {
+  trait ExprMagnet {
     def map(expr: Expression): Expression
   }
   private object ExprMagnet {
@@ -68,7 +68,7 @@ object Mappers {
   }
 
   // ********** Type Mappers **********
-  private trait TypeMagnet {
+  trait TypeMagnet {
     def map(tpe: Type): Type
   }
   private object TypeMagnet {
@@ -84,7 +84,7 @@ object Mappers {
   }
 
   // ********** Width Mappers **********
-  private trait WidthMagnet {
+  trait WidthMagnet {
     def map(width: Width): Width
   }
   private object WidthMagnet {
@@ -100,7 +100,7 @@ object Mappers {
   }
 
   // ********** Module Mappers **********
-  private trait ModuleMagnet {
+  trait ModuleMagnet {
     def map(module: DefModule): DefModule
   }
   private object ModuleMagnet {
@@ -122,7 +122,7 @@ object Mappers {
   }
 
   // ********** Circuit Mappers **********
-  private trait CircuitMagnet {
+  trait CircuitMagnet {
     def map(module: Circuit): Circuit
   }
   private object CircuitMagnet {

src/main/scala/firrtl/Namespace.scala

@@ -27,10 +27,12 @@ class Namespace private {
     else {
       var idx = indices.getOrElse(value, 0)
       var str = value
-      do {
+      var cond = true
+      while (cond) {
         str = s"${value}_$idx"
         idx += 1
-      } while (!(tryName(str)))
+        cond = !tryName(str)
+      }
       indices(value) = idx
       str
     }

src/main/scala/firrtl/Utils.scala

@@ -403,7 +403,7 @@ object Utils extends LazyLogging {
   /** Returns an inlined expression (replacing node references with values),
     * stopping on a stopping condition or until the reference is not a node
     */
-  def inline(nodeMap: NodeMap, stop: String => Boolean = { x: String => false })(e: Expression): Expression = {
+  def inline(nodeMap: NodeMap, stop: String => Boolean = { (x: String) => false })(e: Expression): Expression = {
     def onExp(e: Expression): Expression = e.map(onExp) match {
       case Reference(name, _, _, _) if nodeMap.contains(name) && !stop(name) => onExp(nodeMap(name))
       case other                                                             => other

src/main/scala/firrtl/annotations/JsonProtocol.scala

@@ -292,8 +292,7 @@ object JsonProtocol extends LazyLogging {
   }
 
   def deserializeTry(in: JsonInput, allowUnrecognizedAnnotations: Boolean = false): Try[Seq[Annotation]] = Try {
-    val parsed = parse(in)
-    val annos = parsed match {
+    val annos: Seq[JValue] = parse(in) match {
       case JArray(objs) => objs
       case x =>
         throw new InvalidAnnotationJSONException(

src/main/scala/firrtl/backends/experimental/rtlil/RtlilEmitter.scala

@@ -15,6 +15,7 @@ import firrtl.options.{CustomFileEmission, Dependency}
 import firrtl.passes.LowerTypes
 import firrtl.passes.MemPortUtils.memPortField
 import firrtl.stage.{FirrtlOptions, TransformManager}
+import firrtl.stage.FirrtlOptionsView
 
 import scala.annotation.tailrec
 import scala.collection.mutable

src/main/scala/firrtl/backends/experimental/smt/SMTEmitter.scala

@@ -9,7 +9,7 @@ import firrtl._
 import firrtl.annotations.{Annotation, NoTargetAnnotation}
 import firrtl.options.Viewer.view
 import firrtl.options.{CustomFileEmission, Dependency}
-import firrtl.stage.FirrtlOptions
+import firrtl.stage.{FirrtlOptions, FirrtlOptionsView}
 
 private[firrtl] abstract class SMTEmitter private[firrtl] ()
     extends Transform

src/main/scala/firrtl/constraint/Constraint.scala

@@ -6,7 +6,7 @@ package firrtl.constraint
 trait Constraint {
   def serialize: String
   def map(f: Constraint => Constraint): Constraint
-  val children: Vector[Constraint]
+  def children: Vector[Constraint]
   def reduce(): Constraint
 }
 

src/main/scala/firrtl/constraint/IsFloor.scala

@@ -22,7 +22,7 @@ case class IsFloor private (child: Constraint, dummyArg: Int) extends Constraint
     case x: IsFloor => x
     case _ => this
   }
-  val children = Vector(child)
+  lazy val children = Vector(child)
 
   override def map(f: Constraint => Constraint): Constraint = IsFloor(f(child))
 

src/main/scala/firrtl/constraint/IsKnown.scala

@@ -36,7 +36,7 @@ trait IsKnown extends Constraint {
 
   override def map(f: Constraint => Constraint): Constraint = this
 
-  val children: Vector[Constraint] = Vector.empty[Constraint]
+  lazy val children: Vector[Constraint] = Vector.empty[Constraint]
 
   def reduce(): IsKnown = this
 }

src/main/scala/firrtl/constraint/IsPow.scala

@@ -23,7 +23,7 @@ case class IsPow private (child: Constraint, dummyArg: Int) extends Constraint {
     case _ => this
   }
 
-  val children = Vector(child)
+  lazy val children = Vector(child)
 
   override def map(f: Constraint => Constraint): Constraint = IsPow(f(child))
 

src/main/scala/firrtl/constraint/IsVar.scala

@@ -20,7 +20,7 @@ trait IsVar extends Constraint {
 
   override def reduce() = this
 
-  val children = Vector()
+  lazy val children = Vector()
 }
 
 case class VarCon(name: String) extends IsVar

src/main/scala/firrtl/graph/DiGraph.scala

@@ -279,11 +279,13 @@ class DiGraph[T](private[graph] val edges: LinkedHashMap[T, LinkedHashSet[T]]) {
         if (frame.childCall.isEmpty) {
           if (lowlinks(v) == indices(v)) {
             val scc = new mutable.ArrayBuffer[T]
-            do {
+            var cond = true
+            while (cond) {
               val w = stack.pop()
               onstack -= w
               scc += w
-            } while (scc.last != v);
+              cond = scc.last != v
+            }
             sccs.append(scc.toSeq)
           }
           callStack.pop()

src/main/scala/firrtl/ir/IR.scala

@@ -884,13 +884,13 @@ case object UnknownBound extends Bound {
   def serialize: String = Serializer.serialize(this)
   def map(f: Constraint => Constraint): Constraint = this
   override def reduce(): Constraint = this
-  val children = Vector()
+  lazy val children = Vector()
 }
 case class CalcBound(arg: Constraint) extends Bound {
   def serialize: String = Serializer.serialize(this)
   def map(f: Constraint => Constraint): Constraint = f(arg)
   override def reduce(): Constraint = arg
-  val children = Vector(arg)
+  lazy val children = Vector(arg)
 }
 case class VarBound(name: String) extends IsVar with Bound {
   override def serialize: String = Serializer.serialize(this)
@@ -1039,7 +1039,7 @@ case class IntervalType(lower: Bound, upper: Bound, point: Width) extends Ground
   })
 
   /** If bounds are known, calculates the width, otherwise returns UnknownWidth */
-  lazy val width: Width = (point, lower, upper) match {
+  val width: Width = (point, lower, upper) match {
     case (IntWidth(i), l: IsKnown, u: IsKnown) =>
       IntWidth(Math.max(Utils.getSIntWidth(minAdjusted.get), Utils.getSIntWidth(maxAdjusted.get)))
     case _ => UnknownWidth

src/main/scala/firrtl/ir/Serializer.scala

@@ -190,7 +190,7 @@ object Serializer {
 
     // We could initialze the StringBuilder size, but this is bad for small modules which may not
     // even reach the bufferSize.
-    private implicit val b = new StringBuilder
+    private implicit val b: StringBuilder = new StringBuilder
 
     // The flattening of Whens into WhenBegin and friends requires us to keep track of the
     // indention level

src/main/scala/firrtl/options/OptionParser.scala

@@ -11,7 +11,7 @@ case object OptionsHelpException extends Exception("Usage help invoked")
 /** OptionParser mixin that causes the OptionParser to not call exit (call `sys.exit`) if the `--help` option is
   * passed
   */
-trait DoNotTerminateOnExit { this: OptionParser[_] =>
+trait DoNotTerminateOnExit[T] extends OptionParser[T] {
   override def terminate(exitState: Either[String, Unit]): Unit = ()
 }
 
@@ -21,7 +21,7 @@ trait DoNotTerminateOnExit { this: OptionParser[_] =>
   * [[StageUtils.dramaticError]]. By converting this to an [[OptionsException]], a [[Stage]] can then catch the error an
   * convert it to an [[OptionsException]] that a [[Stage]] can get at.
   */
-trait ExceptOnError { this: OptionParser[_] =>
+trait ExceptOnError[T] extends OptionParser[T] {
   override def reportError(msg: String): Unit = throw new OptionsException(msg)
 }
 

src/main/scala/firrtl/options/Phase.scala

@@ -34,7 +34,10 @@ object Dependency {
   }
 
   private def isSingleton(obj: AnyRef): Boolean = {
-    reflect.runtime.currentMirror.reflect(obj).symbol.isModuleClass
+    // https://stackoverflow.com/questions/36018355/in-scala-is-there-any-way-to-check-if-an-instance-is-a-singleton-object-or-not
+    // https://stackoverflow.com/questions/37388677/how-to-check-if-a-value-is-a-scala-singleton-object-without-a-static-type?noredirect=1&lq=1
+    // reflect.runtime.currentMirror.reflect(obj).symbol.isModuleClass
+    obj.getClass.getName.endsWith("$")
   }
 }
 
@@ -55,7 +58,7 @@ case class Dependency[+A <: DependencyAPI[_]](id: Either[Class[_ <: A], A with S
   }
 
   /** Wrap an [[IllegalAccessException]] due to attempted object construction in a [[DependencyManagerException]] */
-  private def safeConstruct[A](a: Class[_ <: A]): A = try { a.newInstance }
+  private def safeConstruct[A](a: Class[_ <: A]): A = try { a.getDeclaredConstructor().newInstance() }
   catch {
     case e: IllegalAccessException =>
       throw new DependencyManagerException(s"Failed to construct '$a'! (Did you try to construct an object?)", e)
@@ -192,7 +195,7 @@ trait DependencyAPI[A <: DependencyAPI[A]] { this: TransformLike[_] =>
   "Use an explicit `override def invalidates` returning false. This will be removed in FIRRTL 1.5.",
   "FIRRTL 1.4"
 )
-trait PreservesAll[A <: DependencyAPI[A]] { this: DependencyAPI[A] =>
+trait PreservesAll[A <: DependencyAPI[A]] { this: DependencyAPI[A] with TransformLike[_] =>
 
   override final def invalidates(a: A): Boolean = false
 

src/main/scala/firrtl/options/Shell.scala

@@ -16,10 +16,10 @@ import java.util.ServiceLoader
 class Shell(val applicationName: String) {
 
   /** Command line argument parser (OptionParser) with modifications */
-  protected val parser = new OptionParser[AnnotationSeq](applicationName)
+  val parser = new OptionParser[AnnotationSeq](applicationName)
     with DuplicateHandling
-    with ExceptOnError
-    with DoNotTerminateOnExit
+    with ExceptOnError[AnnotationSeq]
+    with DoNotTerminateOnExit[AnnotationSeq]
 
   /** Contains all discovered [[RegisteredLibrary]] */
   final lazy val registeredLibraries: Seq[RegisteredLibrary] = {

src/main/scala/firrtl/options/phases/GetIncludes.scala

@@ -7,6 +7,7 @@ import firrtl.annotations.{AnnotationFileNotFoundException, JsonProtocol}
 import firrtl.options.{InputAnnotationFileAnnotation, Phase, StageUtils}
 import firrtl.FileUtils
 import firrtl.stage.AllowUnrecognizedAnnotations
+import org.json4s.FileInput
 
 import java.io.File
 import scala.collection.mutable
@@ -31,7 +32,7 @@ class GetIncludes extends Phase {
   ): AnnotationSeq = {
     val file = new File(filename).getCanonicalFile
     if (!file.exists) { throw new AnnotationFileNotFoundException(file) }
-    JsonProtocol.deserialize(file, allowUnrecognizedAnnotations)
+    JsonProtocol.deserialize(FileInput(file), allowUnrecognizedAnnotations)
   }
 
   /** Recursively read all [[Annotation]]s from any [[InputAnnotationFileAnnotation]]s while making sure that each file is

src/main/scala/firrtl/options/phases/WriteOutputAnnotations.scala

@@ -14,6 +14,7 @@ import firrtl.options.{
   Unserializable,
   Viewer
 }
+import firrtl.options.StageOptionsView
 
 import java.io.{BufferedOutputStream, File, FileOutputStream, PrintWriter}