Get rid of SelectFromType tree node.

Roll its functionality into Select. Since we can always
tell whether a tree is a type or term there is no expressiveness
gained by having a separate tree node.

Author: odersky

src/dotty/tools/dotc/ast/TreeInfo.scala

@@ -182,7 +182,7 @@ trait TreeInfo[T >: Untyped <: Type] { self: Trees.Instance[T] =>
     case OrTypeTree(tpt1, tpt2) => mayBeTypePat(tpt1) || mayBeTypePat(tpt2)
     case RefinedTypeTree(tpt, refinements) => mayBeTypePat(tpt) || refinements.exists(_.isInstanceOf[Bind])
     case AppliedTypeTree(tpt, args) => mayBeTypePat(tpt) || args.exists(_.isInstanceOf[Bind])
-    case SelectFromTypeTree(tpt, _) => mayBeTypePat(tpt)
+    case Select(tpt, _) => mayBeTypePat(tpt)
     case Annotated(tpt, _) => mayBeTypePat(tpt)
     case _ => false
   }

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

@@ -364,7 +364,7 @@ object Trees {
     override def toString = s"BackquotedIdent($name)"
   }
 
-  /** qualifier.name */
+  /** qualifier.name, or qualifier#name, if qualifier is a type */
   case class Select[-T >: Untyped] private[ast] (qualifier: Tree[T], name: Name)
     extends RefTree[T] {
     type ThisTree[-T >: Untyped] = Select[T]
@@ -549,15 +549,6 @@ object Trees {
     type ThisTree[-T >: Untyped] = SingletonTypeTree[T]
   }
 
-  /** qualifier # name
-   *  In Scala, this always refers to a type, but in a Java
-   *  compilation unit this might refer to a term.
-   */
-  case class SelectFromTypeTree[-T >: Untyped] private[ast] (qualifier: Tree[T], name: Name)
-    extends RefTree[T] {
-    type ThisTree[-T >: Untyped] = SelectFromTypeTree[T]
-  }
-
   /** left & right */
   case class AndTypeTree[-T >: Untyped] private[ast] (left: Tree[T], right: Tree[T])
     extends TypTree[T] {
@@ -841,7 +832,6 @@ object Trees {
     type JavaSeqLiteral = Trees.JavaSeqLiteral[T]
     type TypeTree = Trees.TypeTree[T]
     type SingletonTypeTree = Trees.SingletonTypeTree[T]
-    type SelectFromTypeTree = Trees.SelectFromTypeTree[T]
     type AndTypeTree = Trees.AndTypeTree[T]
     type OrTypeTree = Trees.OrTypeTree[T]
     type RefinedTypeTree = Trees.RefinedTypeTree[T]
@@ -1000,10 +990,6 @@ object Trees {
         case tree: SingletonTypeTree if ref eq tree.ref => tree
         case _ => finalize(tree, untpd.SingletonTypeTree(ref))
       }
-      def SelectFromTypeTree(tree: Tree)(qualifier: Tree, name: Name): SelectFromTypeTree = tree match {
-        case tree: SelectFromTypeTree if (qualifier eq tree.qualifier) && (name == tree.name) => tree
-        case _ => finalize(tree, untpd.SelectFromTypeTree(qualifier, name))
-      }
       def AndTypeTree(tree: Tree)(left: Tree, right: Tree): AndTypeTree = tree match {
         case tree: AndTypeTree if (left eq tree.left) && (right eq tree.right) => tree
         case _ => finalize(tree, untpd.AndTypeTree(left, right))
@@ -1144,8 +1130,6 @@ object Trees {
           tree
         case SingletonTypeTree(ref) =>
           cpy.SingletonTypeTree(tree)(transform(ref))
-        case SelectFromTypeTree(qualifier, name) =>
-          cpy.SelectFromTypeTree(tree)(transform(qualifier), name)
         case AndTypeTree(left, right) =>
           cpy.AndTypeTree(tree)(transform(left), transform(right))
         case OrTypeTree(left, right) =>
@@ -1248,8 +1232,6 @@ object Trees {
             x
           case SingletonTypeTree(ref) =>
             this(x, ref)
-          case SelectFromTypeTree(qualifier, name) =>
-            this(x, qualifier)
           case AndTypeTree(left, right) =>
             this(this(x, left), right)
           case OrTypeTree(left, right) =>
@@ -1325,7 +1307,6 @@ object Trees {
         case tree: DefDef => cpy.DefDef(tree)(name = newName.asTermName)
         case tree: untpd.PolyTypeDef => untpd.cpy.PolyTypeDef(tree)(newName.asTypeName, tree.tparams, tree.rhs).withMods(tree.rawMods)
         case tree: TypeDef => cpy.TypeDef(tree)(name = newName.asTypeName)
-        case tree: SelectFromTypeTree => cpy.SelectFromTypeTree(tree)(tree.qualifier, newName)
       }
     }.asInstanceOf[tree.ThisTree[T]]
   }

src/dotty/tools/dotc/ast/tpd.scala

@@ -30,11 +30,8 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
   def Select(qualifier: Tree, name: Name)(implicit ctx: Context): Select =
     ta.assignType(untpd.Select(qualifier, name), qualifier)
 
-  def SelectFromTypeTree(qualifier: Tree, name: Name)(implicit ctx: Context): SelectFromTypeTree =
-    ta.assignType(untpd.SelectFromTypeTree(qualifier, name), qualifier)
-
-  def SelectFromTypeTree(qualifier: Tree, tp: NamedType)(implicit ctx: Context): SelectFromTypeTree =
-    untpd.SelectFromTypeTree(qualifier, tp.name).withType(tp)
+  def Select(qualifier: Tree, tp: NamedType)(implicit ctx: Context): Select =
+    untpd.Select(qualifier, tp.name).withType(tp)
 
   def This(cls: ClassSymbol)(implicit ctx: Context): This =
     untpd.This(cls.name).withType(cls.thisType)
@@ -333,7 +330,7 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
       Ident(tp)
     else tp.prefix match {
       case pre: SingletonType => followOuterLinks(singleton(pre)).select(tp)
-      case pre => SelectFromTypeTree(TypeTree(pre), tp)
+      case pre => Select(TypeTree(pre), tp)
     } // no checks necessary
 
   def ref(sym: Symbol)(implicit ctx: Context): Tree =

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

@@ -154,7 +154,6 @@ object untpd extends Trees.Instance[Untyped] with UntypedTreeInfo {
   def TypeTree(original: Tree): TypeTree = new TypeTree(original)
   def TypeTree() = new TypeTree(EmptyTree)
   def SingletonTypeTree(ref: Tree): SingletonTypeTree = new SingletonTypeTree(ref)
-  def SelectFromTypeTree(qualifier: Tree, name: Name): SelectFromTypeTree = new SelectFromTypeTree(qualifier, name)
   def AndTypeTree(left: Tree, right: Tree): AndTypeTree = new AndTypeTree(left, right)
   def OrTypeTree(left: Tree, right: Tree): OrTypeTree = new OrTypeTree(left, right)
   def RefinedTypeTree(tpt: Tree, refinements: List[Tree]): RefinedTypeTree = new RefinedTypeTree(tpt, refinements)

src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala

@@ -1194,7 +1194,7 @@ class Scala2Unpickler(bytes: Array[Byte], classRoot: ClassDenotation, moduleClas
       case SELECTFROMTYPEtree =>
         val qualifier = readTreeRef()
         val selector = readTypeNameRef()
-        SelectFromTypeTree(qualifier, symbol.namedType)
+        Select(qualifier, symbol.namedType)
 
       case COMPOUNDTYPEtree =>
         readTemplateRef()

src/dotty/tools/dotc/parsing/JavaParsers.scala

@@ -227,7 +227,7 @@ object JavaParsers {
     def convertToTypeId(tree: Tree): Tree = convertToTypeName(tree) match {
       case Some(t)  => t withPos tree.pos
       case _        => tree match {
-        case AppliedTypeTree(_, _) | SelectFromTypeTree(_, _) =>
+        case AppliedTypeTree(_, _) | Select(_, _) =>
           tree
         case _ =>
           syntaxError("identifier expected", tree.pos)
@@ -285,10 +285,10 @@ object JavaParsers {
           // SelectFromTypeTree otherwise. See #3567.
           // Select nodes can be later
           // converted in the typechecker to SelectFromTypeTree if the class
-          // turns out to be an instance ionner class instead of a static inner class.
+          // turns out to be an instance inner class instead of a static inner class.
           def typeSelect(t: Tree, name: Name) = t match {
             case Ident(_) | Select(_, _) => Select(t, name)
-            case _ => SelectFromTypeTree(t, name.toTypeName)
+            case _ => Select(t, name.toTypeName)
           }
           while (in.token == DOT) {
             in.nextToken()

src/dotty/tools/dotc/parsing/Parsers.scala

@@ -795,7 +795,7 @@ object Parsers {
     private def typeProjection(t: Tree): Tree = {
       accept(HASH)
       val id = typeIdent()
-      atPos(t.pos.start, id.pos.start) { SelectFromTypeTree(t, id.name) }
+      atPos(t.pos.start, id.pos.start) { Select(t, id.name) }
     }
 
     /** NamedTypeArg      ::=  id `=' Type

src/dotty/tools/dotc/printing/RefinedPrinter.scala

@@ -281,7 +281,8 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
           case _ => toText(name)
         }
       case tree @ Select(qual, name) =>
-        toTextLocal(qual) ~ ("." ~ nameIdText(tree) provided name != nme.CONSTRUCTOR)
+        if (qual.isType) toTextLocal(qual) ~ "#" ~ toText(name)
+        else toTextLocal(qual) ~ ("." ~ nameIdText(tree) provided name != nme.CONSTRUCTOR)
       case tree: This =>
         optDotPrefix(tree) ~ "this" ~ idText(tree)
       case Super(qual: This, mix) =>
@@ -349,8 +350,6 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
         if (tree.hasType) toText(tree.typeOpt) else toText(orig)
       case SingletonTypeTree(ref) =>
         toTextLocal(ref) ~ ".type"
-      case SelectFromTypeTree(qual, name) =>
-        toTextLocal(qual) ~ "#" ~ toText(name)
       case AndTypeTree(l, r) =>
         changePrec(AndPrec) { toText(l) ~ " & " ~ toText(r) }
       case OrTypeTree(l, r) =>

src/dotty/tools/dotc/transform/Erasure.scala

@@ -388,9 +388,6 @@ object Erasure extends TypeTestsCasts{
       recur(typed(tree.qualifier, AnySelectionProto))
     }
 
-    override def typedSelectFromTypeTree(tree: untpd.SelectFromTypeTree, pt: Type)(implicit ctx: Context) =
-      untpd.Ident(tree.name).withPos(tree.pos).withType(erasedType(tree))
-
     override def typedThis(tree: untpd.This)(implicit ctx: Context): Tree =
       if (tree.symbol == ctx.owner.enclosingClass || tree.symbol.isStaticOwner) promote(tree)
       else {

src/dotty/tools/dotc/transform/TreeTransform.scala

@@ -82,7 +82,6 @@ object TreeTransforms {
     def prepareForTry(tree: Try)(implicit ctx: Context) = this
     def prepareForSeqLiteral(tree: SeqLiteral)(implicit ctx: Context) = this
     def prepareForTypeTree(tree: TypeTree)(implicit ctx: Context) = this
-    def prepareForSelectFromTypeTree(tree: SelectFromTypeTree)(implicit ctx: Context) = this
     def prepareForBind(tree: Bind)(implicit ctx: Context) = this
     def prepareForAlternative(tree: Alternative)(implicit ctx: Context) = this
     def prepareForTypeDef(tree: TypeDef)(implicit ctx: Context) = this
@@ -114,7 +113,6 @@ object TreeTransforms {
     def transformTry(tree: Try)(implicit ctx: Context, info: TransformerInfo): Tree = tree
     def transformSeqLiteral(tree: SeqLiteral)(implicit ctx: Context, info: TransformerInfo): Tree = tree
     def transformTypeTree(tree: TypeTree)(implicit ctx: Context, info: TransformerInfo): Tree = tree
-    def transformSelectFromTypeTree(tree: SelectFromTypeTree)(implicit ctx: Context, info: TransformerInfo): Tree = tree
     def transformBind(tree: Bind)(implicit ctx: Context, info: TransformerInfo): Tree = tree
     def transformAlternative(tree: Alternative)(implicit ctx: Context, info: TransformerInfo): Tree = tree
     def transformUnApply(tree: UnApply)(implicit ctx: Context, info: TransformerInfo): Tree = tree
@@ -276,7 +274,6 @@ object TreeTransforms {
       nxPrepTry = index(transformations, "prepareForTry")
       nxPrepSeqLiteral = index(transformations, "prepareForSeqLiteral")
       nxPrepTypeTree = index(transformations, "prepareForTypeTree")
-      nxPrepSelectFromTypeTree = index(transformations, "prepareForSelectFromTypeTree")
       nxPrepBind = index(transformations, "prepareForBind")
       nxPrepAlternative = index(transformations, "prepareForAlternative")
       nxPrepUnApply = index(transformations, "prepareForUnApply")
@@ -307,7 +304,6 @@ object TreeTransforms {
       nxTransTry = index(transformations, "transformTry")
       nxTransSeqLiteral = index(transformations, "transformSeqLiteral")
       nxTransTypeTree = index(transformations, "transformTypeTree")
-      nxTransSelectFromTypeTree = index(transformations, "transformSelectFromTypeTree")
       nxTransBind = index(transformations, "transformBind")
       nxTransAlternative = index(transformations, "transformAlternative")
       nxTransUnApply = index(transformations, "transformUnApply")
@@ -348,7 +344,6 @@ object TreeTransforms {
       nxPrepTry = indexUpdate(prev.nxPrepTry, changedTransformationClass, transformationIndex, "prepareForTry", copy)
       nxPrepSeqLiteral = indexUpdate(prev.nxPrepSeqLiteral, changedTransformationClass, transformationIndex, "prepareForSeqLiteral", copy)
       nxPrepTypeTree = indexUpdate(prev.nxPrepTypeTree, changedTransformationClass, transformationIndex, "prepareForTypeTree", copy)
-      nxPrepSelectFromTypeTree = indexUpdate(prev.nxPrepSelectFromTypeTree, changedTransformationClass, transformationIndex, "prepareForSelectFromTypeTree", copy)
       nxPrepBind = indexUpdate(prev.nxPrepBind, changedTransformationClass, transformationIndex, "prepareForBind", copy)
       nxPrepAlternative = indexUpdate(prev.nxPrepAlternative, changedTransformationClass, transformationIndex, "prepareForAlternative", copy)
       nxPrepUnApply = indexUpdate(prev.nxPrepUnApply, changedTransformationClass, transformationIndex, "prepareForUnApply", copy)
@@ -378,7 +373,6 @@ object TreeTransforms {
       nxTransTry = indexUpdate(prev.nxTransTry, changedTransformationClass, transformationIndex, "transformTry", copy)
       nxTransSeqLiteral = indexUpdate(prev.nxTransSeqLiteral, changedTransformationClass, transformationIndex, "transformSeqLiteral", copy)
       nxTransTypeTree = indexUpdate(prev.nxTransTypeTree, changedTransformationClass, transformationIndex, "transformTypeTree", copy)
-      nxTransSelectFromTypeTree = indexUpdate(prev.nxTransSelectFromTypeTree, changedTransformationClass, transformationIndex, "transformSelectFromTypeTree", copy)
       nxTransBind = indexUpdate(prev.nxTransBind, changedTransformationClass, transformationIndex, "transformBind", copy)
       nxTransAlternative = indexUpdate(prev.nxTransAlternative, changedTransformationClass, transformationIndex, "transformAlternative", copy)
       nxTransUnApply = indexUpdate(prev.nxTransUnApply, changedTransformationClass, transformationIndex, "transformUnApply", copy)
@@ -414,7 +408,6 @@ object TreeTransforms {
     var nxPrepTry: Array[Int] = _
     var nxPrepSeqLiteral: Array[Int] = _
     var nxPrepTypeTree: Array[Int] = _
-    var nxPrepSelectFromTypeTree: Array[Int] = _
     var nxPrepBind: Array[Int] = _
     var nxPrepAlternative: Array[Int] = _
     var nxPrepUnApply: Array[Int] = _
@@ -445,7 +438,6 @@ object TreeTransforms {
     var nxTransTry: Array[Int] = _
     var nxTransSeqLiteral: Array[Int] = _
     var nxTransTypeTree: Array[Int] = _
-    var nxTransSelectFromTypeTree: Array[Int] = _
     var nxTransBind: Array[Int] = _
     var nxTransAlternative: Array[Int] = _
     var nxTransUnApply: Array[Int] = _
@@ -524,7 +516,6 @@ object TreeTransforms {
     val prepForTry: Mutator[Try] = (trans, tree, ctx) => trans.prepareForTry(tree)(ctx)
     val prepForSeqLiteral: Mutator[SeqLiteral] = (trans, tree, ctx) => trans.prepareForSeqLiteral(tree)(ctx)
     val prepForTypeTree: Mutator[TypeTree] = (trans, tree, ctx) => trans.prepareForTypeTree(tree)(ctx)
-    val prepForSelectFromTypeTree: Mutator[SelectFromTypeTree] = (trans, tree, ctx) => trans.prepareForSelectFromTypeTree(tree)(ctx)
     val prepForBind: Mutator[Bind] = (trans, tree, ctx) => trans.prepareForBind(tree)(ctx)
     val prepForAlternative: Mutator[Alternative] = (trans, tree, ctx) => trans.prepareForAlternative(tree)(ctx)
     val prepForUnApply: Mutator[UnApply] = (trans, tree, ctx) => trans.prepareForUnApply(tree)(ctx)
@@ -760,17 +751,6 @@ object TreeTransforms {
       } else tree
     }
 
-    @tailrec
-    final private[TreeTransforms] def goSelectFromTypeTree(tree: SelectFromTypeTree, cur: Int)(implicit ctx: Context, info: TransformerInfo): Tree = {
-      if (cur < info.transformers.length) {
-        val trans = info.transformers(cur)
-        trans.transformSelectFromTypeTree(tree)(ctx.withPhase(trans.treeTransformPhase), info) match {
-          case t: SelectFromTypeTree => goSelectFromTypeTree(t, info.nx.nxTransSelectFromTypeTree(cur + 1))
-          case t => transformSingle(t, cur + 1)
-        }
-      } else tree
-    }
-
     @tailrec
     final private[TreeTransforms] def goBind(tree: Bind, cur: Int)(implicit ctx: Context, info: TransformerInfo): Tree = {
       if (cur < info.transformers.length) {
@@ -880,8 +860,6 @@ object TreeTransforms {
       tree match {
         case tree: Ident => goIdent(tree, info.nx.nxTransIdent(cur))
         case tree: Select => goSelect(tree, info.nx.nxTransSelect(cur))
-        case tree: SelectFromTypeTree =>
-          goSelectFromTypeTree(tree, info.nx.nxTransSelectFromTypeTree(cur))
         case tree: Bind => goBind(tree, cur)
         case tree: ValDef if !tree.isEmpty => goValDef(tree, info.nx.nxTransValDef(cur))
         case tree: DefDef => goDefDef(tree, info.nx.nxTransDefDef(cur))
@@ -946,13 +924,6 @@ object TreeTransforms {
             val qual = transform(tree.qualifier, mutatedInfo, cur)
             goSelect(cpy.Select(tree)(qual, tree.name), mutatedInfo.nx.nxTransSelect(cur))
           }
-        case tree: SelectFromTypeTree =>
-          implicit val mutatedInfo: TransformerInfo = mutateTransformers(info, prepForSelectFromTypeTree, info.nx.nxPrepSelectFromTypeTree, tree, cur)
-          if (mutatedInfo eq null) tree
-          else {
-            val qual = transform(tree.qualifier, mutatedInfo, cur)
-            goSelectFromTypeTree(cpy.SelectFromTypeTree(tree)(qual, tree.name), mutatedInfo.nx.nxTransSelectFromTypeTree(cur))
-          }
         case tree: Bind =>
           implicit val mutatedInfo: TransformerInfo = mutateTransformers(info, prepForBind, info.nx.nxPrepBind, tree, cur)
           if (mutatedInfo eq null) tree

src/dotty/tools/dotc/typer/Checking.scala

@@ -99,8 +99,6 @@ object Checking {
           checkValidIfHKApply(ctx.addMode(Mode.AllowLambdaWildcardApply))
         case Select(qual, name) if name.isTypeName =>
           checkRealizable(qual.tpe, qual.pos)
-        case SelectFromTypeTree(qual, name) if name.isTypeName =>
-          checkRealizable(qual.tpe, qual.pos)
         case SingletonTypeTree(ref) =>
           checkRealizable(ref.tpe, ref.pos)
         case _ =>

src/dotty/tools/dotc/typer/ReTyper.scala

@@ -38,12 +38,6 @@ class ReTyper extends Typer {
     untpd.cpy.Select(tree)(qual1, tree.name).withType(tree.typeOpt)
   }
 
-  override def typedSelectFromTypeTree(tree: untpd.SelectFromTypeTree, pt: Type)(implicit ctx: Context): Tree = {
-    assert(tree.hasType)
-    val qual1 = typed(tree.qualifier, AnySelectionProto)
-    untpd.cpy.SelectFromTypeTree(tree)(qual1, tree.name).withType(tree.typeOpt)
-  }
-
   override def typedLiteral(tree: untpd.Literal)(implicit ctc: Context): Literal =
     promote(tree)
 

src/dotty/tools/dotc/typer/TypeAssigner.scala

@@ -263,9 +263,6 @@ trait TypeAssigner {
     tree.withType(tp)
   }
 
-  def assignType(tree: untpd.SelectFromTypeTree, qual: Tree)(implicit ctx: Context) =
-    tree.withType(accessibleSelectionType(tree, qual))
-
   def assignType(tree: untpd.New, tpt: Tree)(implicit ctx: Context) =
     tree.withType(tpt.tpe)