Plugin generation of Bundle elements is now mandatory

This required implementing _elementsImpl manually for all HWTuple
classes (which do not have the plugin run on them).

build.sbt

@@ -195,7 +195,6 @@ lazy val chisel = (project in file("."))
   .settings(
     mimaPreviousArtifacts := Set(),
     libraryDependencies += defaultVersions("treadle") % "test",
-    Test / scalacOptions += "-P:chiselplugin:genBundleElements",
     Test / scalacOptions ++= Seq("-language:reflectiveCalls"),
     Compile / doc / scalacOptions ++= Seq(
       "-diagrams",

build.sc

@@ -105,7 +105,7 @@ class chisel3CrossModule(val crossScalaVersion: String) extends CommonModule wit
   }
 
   override def scalacOptions = T {
-    super.scalacOptions() ++ Agg(s"-Xplugin:${plugin.jar().path}", "-P:chiselplugin:genBundleElements")
+    super.scalacOptions() ++ Agg(s"-Xplugin:${plugin.jar().path}")
   }
 
   object stdlib extends CommonModule {

core/src/main/scala/chisel3/Aggregate.scala

@@ -1198,11 +1198,11 @@ package experimental {
   * }}}
   */
 abstract class Bundle(implicit compileOptions: CompileOptions) extends Record {
-  assert(
-    _usingPlugin,
+
+  private def mustUsePluginMsg: String =
     "The Chisel compiler plugin is now required for compiling Chisel code. " +
       "Please see https://github.com/chipsalliance/chisel3#build-your-own-chisel-projects."
-  )
+  assert(_usingPlugin, mustUsePluginMsg)
 
   override def className: String = this.getClass.getSimpleName match {
     case name if name.startsWith("$anon$") => "AnonymousBundle" // fallback for anonymous Bundle case
@@ -1228,14 +1228,7 @@ abstract class Bundle(implicit compileOptions: CompileOptions) extends Record {
     *   assert(uint === "h12345678".U) // This will pass
     * }}}
     */
-  final lazy val elements: SeqMap[String, Data] =
-    // _elementsImpl is a method, only call it once
-    _elementsImpl match {
-      // Those not using plugin-generated _elementsImpl use the old reflective implementation
-      case oldElements: VectorMap[_, _] => oldElements.asInstanceOf[VectorMap[String, Data]]
-      // Plugin-generated _elementsImpl are incomplete and need some processing
-      case rawElements => _processRawElements(rawElements)
-    }
+  final lazy val elements: SeqMap[String, Data] = _processRawElements(_elementsImpl)
 
   // The compiler plugin is imperfect at picking out elements statically so we process at runtime
   // checking for errors and filtering out mistakes
@@ -1284,44 +1277,13 @@ abstract class Bundle(implicit compileOptions: CompileOptions) extends Record {
     }: _*)
   }
 
-  /* The old, reflective implementation of Bundle.elements
-   * This method is optionally overwritten by the compiler plugin for much better performance
-   */
-  protected def _elementsImpl: Iterable[(String, Any)] = {
-    val nameMap = LinkedHashMap[String, Data]()
-    for (m <- getPublicFields(classOf[Bundle])) {
-      getBundleField(m) match {
-        case Some(d: Data) =>
-          requireIsChiselType(d)
-
-          if (nameMap contains m.getName) {
-            require(nameMap(m.getName) eq d)
-          } else {
-            nameMap(m.getName) = d
-          }
-        case None =>
-          if (!ignoreSeq) {
-            m.invoke(this) match {
-              case s: scala.collection.Seq[Any] if s.nonEmpty =>
-                s.head match {
-                  // Ignore empty Seq()
-                  case d: Data =>
-                    throwException(
-                      "Public Seq members cannot be used to define Bundle elements " +
-                        s"(found public Seq member '${m.getName}'). " +
-                        "Either use a Vec if all elements are of the same type, or MixedVec if the elements " +
-                        "are of different types. If this Seq member is not intended to construct RTL, mix in the trait " +
-                        "IgnoreSeqInBundle."
-                    )
-                  case _ => // don't care about non-Data Seq
-                }
-              case _ => // not a Seq
-            }
-          }
-      }
-    }
-    VectorMap(nameMap.toSeq.sortWith { case ((an, a), (bn, b)) => (a._id > b._id) || ((a eq b) && (an > bn)) }: _*)
-  }
+  /** This method is implemented by the compiler plugin
+    *
+    * @note For some reason, the Scala compiler errors on child classes if this method is made
+    * virtual. It appears that the way the plugin implements this method is insufficient for
+    * implementing virtual methods. It is probably better kept concrete for future refactoring.
+    */
+  protected def _elementsImpl: Iterable[(String, Any)] = throwException(mustUsePluginMsg)
 
   /**
     * Overridden by [[IgnoreSeqInBundle]] to allow arbitrary Seqs of Chisel elements.

core/src/main/scala/chisel3/experimental/package.scala

@@ -218,6 +218,10 @@ package object experimental {
     // Because this implementation exists in chisel3.core, it cannot compile with the plugin, so we implement the behavior manually
     override protected def _usingPlugin:   Boolean = true
     override protected def _cloneTypeImpl: Bundle = new HWTuple2(chiselTypeClone(_1), chiselTypeClone(_2))
+    override protected def _elementsImpl: Iterable[(String, Any)] = Vector(
+      "_1" -> _1,
+      "_2" -> _2
+    )
   }
 
   /** [[Data]] equivalent of Scala's [[Tuple3]]
@@ -237,6 +241,11 @@ package object experimental {
       chiselTypeClone(_2),
       chiselTypeClone(_3)
     )
+    override protected def _elementsImpl: Iterable[(String, Any)] = Vector(
+      "_1" -> _1,
+      "_2" -> _2,
+      "_3" -> _3
+    )
   }
 
   /** [[Data]] equivalent of Scala's [[Tuple4]]
@@ -258,6 +267,12 @@ package object experimental {
       chiselTypeClone(_3),
       chiselTypeClone(_4)
     )
+    override protected def _elementsImpl: Iterable[(String, Any)] = Vector(
+      "_1" -> _1,
+      "_2" -> _2,
+      "_3" -> _3,
+      "_4" -> _4
+    )
   }
 
   /** [[Data]] equivalent of Scala's [[Tuple5]]
@@ -281,6 +296,13 @@ package object experimental {
       chiselTypeClone(_4),
       chiselTypeClone(_5)
     )
+    override protected def _elementsImpl: Iterable[(String, Any)] = Vector(
+      "_1" -> _1,
+      "_2" -> _2,
+      "_3" -> _3,
+      "_4" -> _4,
+      "_5" -> _5
+    )
   }
 
   /** [[Data]] equivalent of Scala's [[Tuple6]]
@@ -306,6 +328,14 @@ package object experimental {
       chiselTypeClone(_5),
       chiselTypeClone(_6)
     )
+    override protected def _elementsImpl: Iterable[(String, Any)] = Vector(
+      "_1" -> _1,
+      "_2" -> _2,
+      "_3" -> _3,
+      "_4" -> _4,
+      "_5" -> _5,
+      "_6" -> _6
+    )
   }
 
   /** [[Data]] equivalent of Scala's [[Tuple7]]
@@ -341,6 +371,15 @@ package object experimental {
       chiselTypeClone(_6),
       chiselTypeClone(_7)
     )
+    override protected def _elementsImpl: Iterable[(String, Any)] = Vector(
+      "_1" -> _1,
+      "_2" -> _2,
+      "_3" -> _3,
+      "_4" -> _4,
+      "_5" -> _5,
+      "_6" -> _6,
+      "_7" -> _7
+    )
   }
 
   /** [[Data]] equivalent of Scala's [[Tuple8]]
@@ -379,6 +418,16 @@ package object experimental {
       chiselTypeClone(_7),
       chiselTypeClone(_8)
     )
+    override protected def _elementsImpl: Iterable[(String, Any)] = Vector(
+      "_1" -> _1,
+      "_2" -> _2,
+      "_3" -> _3,
+      "_4" -> _4,
+      "_5" -> _5,
+      "_6" -> _6,
+      "_7" -> _7,
+      "_8" -> _8
+    )
   }
 
   /** [[Data]] equivalent of Scala's [[Tuple9]]
@@ -420,6 +469,17 @@ package object experimental {
       chiselTypeClone(_8),
       chiselTypeClone(_9)
     )
+    override protected def _elementsImpl: Iterable[(String, Any)] = Vector(
+      "_1" -> _1,
+      "_2" -> _2,
+      "_3" -> _3,
+      "_4" -> _4,
+      "_5" -> _5,
+      "_6" -> _6,
+      "_7" -> _7,
+      "_8" -> _8,
+      "_9" -> _9
+    )
   }
 
   /** [[Data]] equivalent of Scala's [[Tuple9]]
@@ -464,5 +524,17 @@ package object experimental {
       chiselTypeClone(_9),
       chiselTypeClone(_10)
     )
+    override protected def _elementsImpl: Iterable[(String, Any)] = Vector(
+      "_1" -> _1,
+      "_2" -> _2,
+      "_3" -> _3,
+      "_4" -> _4,
+      "_5" -> _5,
+      "_6" -> _6,
+      "_7" -> _7,
+      "_8" -> _8,
+      "_9" -> _9,
+      "_10" -> _10
+    )
   }
 }

plugin/src/main/scala/chisel3/internal/plugin/BundleComponent.scala

@@ -162,9 +162,7 @@ private[plugin] class BundleComponent(val global: Global, arguments: ChiselPlugi
         /* Test to see if the bundle found is amenable to having it's elements
          * converted to an immediate form that will not require reflection
          */
-        def isSupportedBundleType: Boolean = {
-          arguments.genBundleElements && !bundle.mods.hasFlag(Flag.ABSTRACT)
-        }
+        def isSupportedBundleType: Boolean = !bundle.mods.hasFlag(Flag.ABSTRACT)
 
         val elementsImplOpt = if (isSupportedBundleType) {
           /* extract the true fields from the super classes a given bundle

plugin/src/main/scala/chisel3/internal/plugin/ChiselPlugin.scala

@@ -9,8 +9,7 @@ import scala.reflect.internal.util.NoPosition
 import scala.collection.mutable
 
 private[plugin] case class ChiselPluginArguments(
-  val skipFiles:         mutable.HashSet[String] = mutable.HashSet.empty,
-  var genBundleElements: Boolean = false) {
+  val skipFiles: mutable.HashSet[String] = mutable.HashSet.empty) {
   def useBundlePluginOpt = "useBundlePlugin"
   def useBundlePluginFullOpt = s"-P:${ChiselPlugin.name}:$useBundlePluginOpt"
   def genBundleElementsOpt = "genBundleElements"
@@ -62,7 +61,7 @@ class ChiselPlugin(val global: Global) extends Plugin {
   override def init(options: List[String], error: String => Unit): Boolean = {
     for (option <- options) {
       if (option == arguments.useBundlePluginOpt) {
-        val msg = s"'${arguments.useBundlePluginFullOpt}' is now default behavior, you can stop using the scalacOption."
+        val msg = s"'${arguments.useBundlePluginFullOpt}' is now default behavior, you can remove the scalacOption."
         global.reporter.warning(NoPosition, msg)
       } else if (option.startsWith(arguments.skipFilePluginOpt)) {
         val filename = option.stripPrefix(arguments.skipFilePluginOpt)
@@ -71,7 +70,8 @@ class ChiselPlugin(val global: Global) extends Plugin {
         val msg = s"Option -P:${ChiselPlugin.name}:$option should only be used for internal chisel3 compiler purposes!"
         global.reporter.warning(NoPosition, msg)
       } else if (option == arguments.genBundleElementsOpt) {
-        arguments.genBundleElements = true
+        val msg = s"'${arguments.genBundleElementsOpt}' is now default behavior, you can remove the scalacOption."
+        global.reporter.warning(NoPosition, msg)
       } else {
         error(s"Option not understood: '$option'")
       }