Merge pull request #7144 from dotty-staging/refactor-wildcard

Switch to `?` for wildcard types

Author: odersky

compiler/src/dotty/tools/dotc/ast/NavigateAST.scala

@@ -39,9 +39,9 @@ object NavigateAST {
    */
   def untypedPath(tree: tpd.Tree, exactMatch: Boolean = false)(implicit ctx: Context): List[Positioned] =
     tree match {
-      case tree: MemberDef[_] =>
+      case tree: MemberDef[?] =>
         untypedPath(tree.span) match {
-          case path @ (last: DefTree[_]) :: _ => path
+          case path @ (last: DefTree[?]) :: _ => path
           case path if !exactMatch => path
           case _ => Nil
         }
@@ -75,7 +75,7 @@ object NavigateAST {
         val path1 = it.next() match {
           case p: Positioned => singlePath(p, path)
           case m: untpd.Modifiers => childPath(m.productIterator, path)
-          case xs: List[_] => childPath(xs.iterator, path)
+          case xs: List[?] => childPath(xs.iterator, path)
           case _ => path
         }
         if ((path1 ne path) &&
@@ -92,7 +92,7 @@ object NavigateAST {
         // our usage of `productIterator` by something in `Positioned` that takes
         // care of low-level details like this for us.
         p match {
-          case p: WithLazyField[_] =>
+          case p: WithLazyField[?] =>
             p.forceIfLazy
           case _ =>
         }

compiler/src/dotty/tools/dotc/ast/PluggableTransformers.scala

@@ -64,7 +64,7 @@ object PluggableTransformers {
       else finishIdent(ops(tree, old, c), old, c, ops.next)
 
     override def finishIdent(tree: Tree[T], old: Tree[T], c: Context, plugins: Plugins): Tree[T] = tree match {
-      case tree: Ident[_] => postIdent(tree, old, c, plugins.IdentOps)
+      case tree: Ident[?] => postIdent(tree, old, c, plugins.IdentOps)
       case _ => postProcess(tree, old, c, plugins)
     }
 
@@ -73,13 +73,13 @@ object PluggableTransformers {
       else finishSelect(ops(tree, old, c), old, c, ops.next)
 
     override def finishSelect(tree: Tree[T], old: Tree[T], c: Context, plugins: Plugins): Tree[T] = tree match {
-      case tree: Select[_] => postSelect(tree, old, c, plugins.SelectOps)
+      case tree: Select[?] => postSelect(tree, old, c, plugins.SelectOps)
       case _ => postProcess(tree, old, c, plugins)
     }
 
     protected def postProcess(tree: Tree[T], old: Tree[T], c: Context, plugins: Plugins): Tree[T] = tree match {
-      case tree: Ident[_] => finishIdent(tree, old, c, plugins)
-      case tree: Select[_] => finishSelect(tree, old, c, plugins)
+      case tree: Ident[?] => finishIdent(tree, old, c, plugins)
+      case tree: Select[?] => finishSelect(tree, old, c, plugins)
     }
   }
 }

compiler/src/dotty/tools/dotc/ast/Positioned.scala

@@ -128,7 +128,7 @@ abstract class Positioned(implicit @constructorOnly src: SourceFile) extends Pro
         x.contains(that)
       case m: untpd.Modifiers =>
         m.mods.exists(isParent) || m.annotations.exists(isParent)
-      case xs: List[_] =>
+      case xs: List[?] =>
         xs.exists(isParent)
       case _ =>
         false
@@ -195,7 +195,7 @@ abstract class Positioned(implicit @constructorOnly src: SourceFile) extends Pro
       case m: untpd.Modifiers =>
         m.annotations.foreach(check)
         m.mods.foreach(check)
-      case xs: List[_] =>
+      case xs: List[?] =>
         xs.foreach(check)
       case _ =>
     }

compiler/src/dotty/tools/dotc/ast/Trees.scala

@@ -119,14 +119,14 @@ object Trees {
      *   - errors were reported
      */
     private def checkChildrenTyped(it: Iterator[Any])(implicit ctx: Context): Unit =
-      if (!this.isInstanceOf[Import[_]])
+      if (!this.isInstanceOf[Import[?]])
         while (it.hasNext)
           it.next() match {
-            case x: Ident[_] => // untyped idents are used in a number of places in typed trees
-            case x: Tree[_] =>
+            case x: Ident[?] => // untyped idents are used in a number of places in typed trees
+            case x: Tree[?] =>
               assert(x.hasType || ctx.reporter.errorsReported,
                      s"$this has untyped child $x")
-            case xs: List[_] => checkChildrenTyped(xs.iterator)
+            case xs: List[?] => checkChildrenTyped(xs.iterator)
             case _ =>
           }
 
@@ -188,8 +188,8 @@ object Trees {
     def treeSize: Int = {
       var s = 1
       def addSize(elem: Any): Unit = elem match {
-        case t: Tree[_] => s += t.treeSize
-        case ts: List[_] => ts foreach addSize
+        case t: Tree[?] => s += t.treeSize
+        case ts: List[?] => ts foreach addSize
         case _ =>
       }
       productIterator foreach addSize
@@ -203,18 +203,18 @@ object Trees {
 
     override def toText(printer: Printer): Text = printer.toText(this)
 
-    def sameTree(that: Tree[_]): Boolean = {
+    def sameTree(that: Tree[?]): Boolean = {
       def isSame(x: Any, y: Any): Boolean =
         x.asInstanceOf[AnyRef].eq(y.asInstanceOf[AnyRef]) || {
           x match {
-            case x: Tree[_] =>
+            case x: Tree[?] =>
               y match {
-                case y: Tree[_] => x.sameTree(y)
+                case y: Tree[?] => x.sameTree(y)
                 case _ => false
               }
-            case x: List[_] =>
+            case x: List[?] =>
               y match {
-                case y: List[_] => x.corresponds(y)(isSame)
+                case y: List[?] => x.corresponds(y)(isSame)
                 case _ => false
               }
             case _ =>
@@ -771,7 +771,7 @@ object Trees {
     type ThisTree[-T >: Untyped] = TypeDef[T]
 
     /** Is this a definition of a class? */
-    def isClassDef: Boolean = rhs.isInstanceOf[Template[_]]
+    def isClassDef: Boolean = rhs.isInstanceOf[Template[?]]
 
     def isBackquoted: Boolean = hasAttachment(Backquoted)
   }

compiler/src/dotty/tools/dotc/ast/untpd.scala

@@ -241,7 +241,7 @@ object untpd extends Trees.Instance[Untyped] with UntypedTreeInfo {
     def hasFlags: Boolean = flags != EmptyFlags
     def hasAnnotations: Boolean = annotations.nonEmpty
     def hasPrivateWithin: Boolean = privateWithin != tpnme.EMPTY
-    def hasMod(cls: Class[_]) = mods.exists(_.getClass == cls)
+    def hasMod(cls: Class[?]) = mods.exists(_.getClass == cls)
 
     private def isEnum = is(Enum, butNot = JavaDefined)
 

compiler/src/dotty/tools/dotc/config/CompilerCommand.scala

@@ -68,11 +68,11 @@ object CompilerCommand {
     val settings = ctx.settings
 
     /** Creates a help message for a subset of options based on cond */
-    def availableOptionsMsg(cond: Setting[_] => Boolean): String = {
+    def availableOptionsMsg(cond: Setting[?] => Boolean): String = {
       val ss                  = (ctx.settings.allSettings filter cond).toList sortBy (_.name)
       val width               = (ss map (_.name.length)).max
       def format(s: String)   = ("%-" + width + "s") format s
-      def helpStr(s: Setting[_]) = {
+      def helpStr(s: Setting[?]) = {
         def defaultValue = s.default match {
           case _: Int | _: String => s.default.toString
           case _ =>
@@ -91,7 +91,7 @@ object CompilerCommand {
       ss map helpStr mkString "\n"
     }
 
-    def createUsageMsg(label: String, shouldExplain: Boolean, cond: Setting[_] => Boolean): String = {
+    def createUsageMsg(label: String, shouldExplain: Boolean, cond: Setting[?] => Boolean): String = {
       val prefix = List(
         Some(shortUsage),
         Some(explainAdvanced) filter (_ => shouldExplain),
@@ -101,9 +101,9 @@ object CompilerCommand {
       prefix + "\n" + availableOptionsMsg(cond)
     }
 
-    def isStandard(s: Setting[_]): Boolean = !isAdvanced(s) && !isPrivate(s)
-    def isAdvanced(s: Setting[_]): Boolean = s.name startsWith "-X"
-    def isPrivate(s: Setting[_]) : Boolean = s.name startsWith "-Y"
+    def isStandard(s: Setting[?]): Boolean = !isAdvanced(s) && !isPrivate(s)
+    def isAdvanced(s: Setting[?]): Boolean = s.name startsWith "-X"
+    def isPrivate(s: Setting[?]) : Boolean = s.name startsWith "-Y"
 
     /** Messages explaining usage and options */
     def usageMessage    = createUsageMsg("where possible standard", shouldExplain = false, isStandard)

compiler/src/dotty/tools/dotc/config/Properties.scala

@@ -10,7 +10,7 @@ import java.util.jar.Attributes.{ Name => AttributeName }
 /** Loads `library.properties` from the jar. */
 object Properties extends PropertiesTrait {
   protected def propCategory: String = "compiler"
-  protected def pickJarBasedOn: Class[Option[_]] = classOf[Option[_]]
+  protected def pickJarBasedOn: Class[Option[?]] = classOf[Option[?]]
 
   /** Scala manifest attributes.
    */
@@ -19,7 +19,7 @@ object Properties extends PropertiesTrait {
 
 trait PropertiesTrait {
   protected def propCategory: String      // specializes the remainder of the values
-  protected def pickJarBasedOn: Class[_]  // props file comes from jar containing this
+  protected def pickJarBasedOn: Class[?]  // props file comes from jar containing this
 
   /** The name of the properties file */
   protected val propFilename: String = "/" + propCategory + ".properties"

compiler/src/dotty/tools/dotc/config/Settings.scala

@@ -19,9 +19,9 @@ object Settings {
   val BooleanTag: ClassTag[Boolean]      = ClassTag.Boolean
   val IntTag: ClassTag[Int]              = ClassTag.Int
   val StringTag: ClassTag[String]        = ClassTag(classOf[String])
-  val ListTag: ClassTag[List[_]]         = ClassTag(classOf[List[_]])
+  val ListTag: ClassTag[List[?]]         = ClassTag(classOf[List[?]])
   val VersionTag: ClassTag[ScalaVersion] = ClassTag(classOf[ScalaVersion])
-  val OptionTag: ClassTag[Option[_]]     = ClassTag(classOf[Option[_]])
+  val OptionTag: ClassTag[Option[?]]     = ClassTag(classOf[Option[?]])
   val OutputTag: ClassTag[AbstractFile]  = ClassTag(classOf[AbstractFile])
 
   class SettingsState(initialValues: Seq[Any]) {
@@ -65,8 +65,8 @@ object Settings {
     choices: Seq[T] = Nil,
     prefix: String = "",
     aliases: List[String] = Nil,
-    depends: List[(Setting[_], Any)] = Nil,
-    propertyClass: Option[Class[_]] = None)(private[Settings] val idx: Int) {
+    depends: List[(Setting[?], Any)] = Nil,
+    propertyClass: Option[Class[?]] = None)(private[Settings] val idx: Int) {
 
     private[this] var changed: Boolean = false
 
@@ -95,7 +95,7 @@ object Settings {
       if (choices.isEmpty) ""
       else choices match {
         case r: Range => s"${r.head}..${r.last}"
-        case xs: List[_] => xs.mkString(", ")
+        case xs: List[?] => xs.mkString(", ")
       }
 
     def isLegal(arg: Any): Boolean =
@@ -110,7 +110,7 @@ object Settings {
             case x: Int => r.head <= x && x <= r.last
             case _ => false
           }
-        case xs: List[_] =>
+        case xs: List[?] =>
           xs contains arg
       }
 
@@ -193,12 +193,12 @@ object Settings {
 
   class SettingGroup {
 
-    private[this] val _allSettings = new ArrayBuffer[Setting[_]]
-    def allSettings: Seq[Setting[_]] = _allSettings.toSeq
+    private[this] val _allSettings = new ArrayBuffer[Setting[?]]
+    def allSettings: Seq[Setting[?]] = _allSettings.toSeq
 
     def defaultState: SettingsState = new SettingsState(allSettings map (_.default))
 
-    def userSetSettings(state: SettingsState): Seq[Setting[_]] =
+    def userSetSettings(state: SettingsState): Seq[Setting[?]] =
       allSettings filterNot (_.isDefaultIn(state))
 
     def toConciseString(state: SettingsState): String =
@@ -207,7 +207,7 @@ object Settings {
     private def checkDependencies(state: ArgsSummary): ArgsSummary =
       userSetSettings(state.sstate).foldLeft(state)(checkDependenciesOfSetting)
 
-    private def checkDependenciesOfSetting(state: ArgsSummary, setting: Setting[_]) =
+    private def checkDependenciesOfSetting(state: ArgsSummary, setting: Setting[?]) =
       setting.depends.foldLeft(state) { (s, dep) =>
         val (depSetting, reqValue) = dep
         if (depSetting.valueIn(state.sstate) == reqValue) s
@@ -237,7 +237,7 @@ object Settings {
         case "--" :: args =>
           checkDependencies(stateWithArgs(skipped ++ args))
         case x :: _ if x startsWith "-" =>
-          @tailrec def loop(settings: List[Setting[_]]): ArgsSummary = settings match {
+          @tailrec def loop(settings: List[Setting[?]]): ArgsSummary = settings match {
             case setting :: settings1 =>
               val state1 = setting.tryToSet(state)
               if (state1 ne state) processArguments(state1, processAll, skipped)

compiler/src/dotty/tools/dotc/config/WrappedProperties.scala

@@ -12,7 +12,7 @@ trait WrappedProperties extends PropertiesTrait {
   def wrap[T](body: => T): Option[T]
 
   protected def propCategory: String     = "wrapped"
-  protected def pickJarBasedOn: Class[_] = this.getClass
+  protected def pickJarBasedOn: Class[?] = this.getClass
 
   override def propIsSet(name: String): Boolean              = wrap(super.propIsSet(name)) exists (x => x)
   override def propOrElse(name: String, alt: String): String = wrap(super.propOrElse(name, alt)) getOrElse alt

compiler/src/dotty/tools/dotc/core/Contexts.scala

@@ -114,9 +114,9 @@ object Contexts {
     final def owner: Symbol = _owner
 
     /** The current tree */
-    private[this] var _tree: Tree[_ >: Untyped]= _
-    protected def tree_=(tree: Tree[_ >: Untyped]): Unit = _tree = tree
-    final def tree: Tree[_ >: Untyped] = _tree
+    private[this] var _tree: Tree[? >: Untyped]= _
+    protected def tree_=(tree: Tree[? >: Untyped]): Unit = _tree = tree
+    final def tree: Tree[? >: Untyped] = _tree
 
     /** The current scope */
     private[this] var _scope: Scope = _
@@ -337,7 +337,7 @@ object Contexts {
      *  Note: Currently unused
     def enclTemplate: Context = {
       var c = this
-      while (c != NoContext && !c.tree.isInstanceOf[Template[_]] && !c.tree.isInstanceOf[PackageDef[_]])
+      while (c != NoContext && !c.tree.isInstanceOf[Template[?]] && !c.tree.isInstanceOf[PackageDef[?]])
         c = c.outer
       c
     }*/
@@ -392,15 +392,15 @@ object Contexts {
     }
 
     /** The context of expression `expr` seen as a member of a statement sequence */
-    def exprContext(stat: Tree[_ >: Untyped], exprOwner: Symbol): Context =
+    def exprContext(stat: Tree[? >: Untyped], exprOwner: Symbol): Context =
       if (exprOwner == this.owner) this
       else if (untpd.isSuperConstrCall(stat) && this.owner.isClass) superCallContext
       else ctx.fresh.setOwner(exprOwner)
 
     /** A new context that summarizes an import statement */
-    def importContext(imp: Import[_], sym: Symbol): FreshContext = {
+    def importContext(imp: Import[?], sym: Symbol): FreshContext = {
       val impNameOpt = imp.expr match {
-        case ref: RefTree[_] => Some(ref.name.asTermName)
+        case ref: RefTree[?] => Some(ref.name.asTermName)
         case _               => None
       }
       ctx.fresh.setImportInfo(
@@ -524,7 +524,7 @@ object Contexts {
     def setPeriod(period: Period): this.type = { this.period = period; this }
     def setMode(mode: Mode): this.type = { this.mode = mode; this }
     def setOwner(owner: Symbol): this.type = { assert(owner != NoSymbol); this.owner = owner; this }
-    def setTree(tree: Tree[_ >: Untyped]): this.type = { this.tree = tree; this }
+    def setTree(tree: Tree[? >: Untyped]): this.type = { this.tree = tree; this }
     def setScope(scope: Scope): this.type = { this.scope = scope; this }
     def setNewScope: this.type = { this.scope = newScope; this }
     def setTyperState(typerState: TyperState): this.type = { this.typerState = typerState; this }
@@ -559,7 +559,7 @@ object Contexts {
     def setProperty[T](key: Key[T], value: T): this.type =
       setMoreProperties(moreProperties.updated(key, value))
 
-    def dropProperty(key: Key[_]): this.type =
+    def dropProperty(key: Key[?]): this.type =
       setMoreProperties(moreProperties - key)
 
     def addLocation[T](initial: T): Store.Location[T] = {

compiler/src/dotty/tools/dotc/core/Definitions.scala

@@ -850,7 +850,7 @@ class Definitions {
    *  Note that this will also extract the high bound if an
    *  element type is a wildcard. E.g.
    *
-   *     Array[_ <: Array[_ <: Number]]
+   *     Array[? <: Array[? <: Number]]
    *
    *  would match
    *
@@ -1218,10 +1218,10 @@ class Definitions {
   private val typeTags = mutable.Map[TypeName, Name]().withDefaultValue(nme.specializedTypeNames.Object)
 
 //  private val unboxedTypeRef = mutable.Map[TypeName, TypeRef]()
-//  private val javaTypeToValueTypeRef = mutable.Map[Class[_], TypeRef]()
-//  private val valueTypeNamesToJavaType = mutable.Map[TypeName, Class[_]]()
+//  private val javaTypeToValueTypeRef = mutable.Map[Class[?], TypeRef]()
+//  private val valueTypeNamesToJavaType = mutable.Map[TypeName, Class[?]]()
 
-  private def valueTypeRef(name: String, jtype: Class[_], enc: Int, tag: Name): TypeRef = {
+  private def valueTypeRef(name: String, jtype: Class[?], enc: Int, tag: Name): TypeRef = {
     val vcls = ctx.requiredClassRef(name)
     valueTypeEnc(vcls.name) = enc
     typeTags(vcls.name) = tag
@@ -1249,8 +1249,8 @@ class Definitions {
   /** The JVM tag for `tp` if it's a primitive, `java.lang.Object` otherwise. */
   def typeTag(tp: Type)(implicit ctx: Context): Name = typeTags(scalaClassName(tp))
 
-//  /** The `Class[_]` of a primitive value type name */
-//  def valueTypeNameToJavaType(name: TypeName)(implicit ctx: Context): Option[Class[_]] =
+//  /** The `Class[?]` of a primitive value type name */
+//  def valueTypeNameToJavaType(name: TypeName)(implicit ctx: Context): Option[Class[?]] =
 //    valueTypeNamesToJavaType.get(if (name.firstPart eq nme.scala_) name.lastPart.toTypeName else name)
 
   type PrimitiveClassEnc = Int

compiler/src/dotty/tools/dotc/core/Phases.scala

@@ -252,7 +252,7 @@ object Phases {
     final def genBCodePhase: Phase = myGenBCodePhase
 
     private def setSpecificPhases() = {
-      def phaseOfClass(pclass: Class[_]) = phases.find(pclass.isInstance).getOrElse(NoPhase)
+      def phaseOfClass(pclass: Class[?]) = phases.find(pclass.isInstance).getOrElse(NoPhase)
 
       myTyperPhase = phaseOfClass(classOf[FrontEnd])
       myPostTyperPhase = phaseOfClass(classOf[PostTyper])
@@ -420,7 +420,7 @@ object Phases {
   /** Replace all instances of `oldPhaseClass` in `current` phases
    *  by the result of `newPhases` applied to the old phase.
    */
-  def replace(oldPhaseClass: Class[_ <: Phase], newPhases: Phase => List[Phase], current: List[List[Phase]]): List[List[Phase]] =
+  def replace(oldPhaseClass: Class[? <: Phase], newPhases: Phase => List[Phase], current: List[List[Phase]]): List[List[Phase]] =
     current.map(_.flatMap(phase =>
       if (oldPhaseClass.isInstance(phase)) newPhases(phase) else phase :: Nil))
 }