From c7205317e1fa59430d2372c27c4d0858b05ffdfc Mon Sep 17 00:00:00 2001
From: Eugene Burmako <xeno.by@gmail.com>
Date: Tue, 5 Feb 2013 11:25:56 +0100
Subject: [nomaster] Revert "DummyTree => CannotHaveAttrs"

This reverts commit 838cbe623c142b7005446793948097f679219fe3.

Conflicts:
	src/reflect/scala/reflect/api/Trees.scala
---
 src/reflect/scala/reflect/api/Trees.scala          | 10 +---------
 src/reflect/scala/reflect/internal/Positions.scala |  2 +-
 src/reflect/scala/reflect/internal/Printers.scala  |  2 +-
 src/reflect/scala/reflect/internal/Trees.scala     | 15 ++++++++-------
 4 files changed, 11 insertions(+), 18 deletions(-)

(limited to 'src/reflect')

diff --git a/src/reflect/scala/reflect/api/Trees.scala b/src/reflect/scala/reflect/api/Trees.scala
index 38835d0f77..869b92a104 100644
--- a/src/reflect/scala/reflect/api/Trees.scala
+++ b/src/reflect/scala/reflect/api/Trees.scala
@@ -75,15 +75,8 @@ trait Trees { self: Universe =>
     def isDef: Boolean
 
     /** Is this tree one of the empty trees?
-     *
      *  Empty trees are: the `EmptyTree` null object, `TypeTree` instances that don't carry a type
      *  and the special `emptyValDef` singleton.
-     *
-     *  In the compiler the `isEmpty` check and the derived `orElse` method are mostly used
-     *  as a check for a tree being a null object (`EmptyTree` for term trees and empty TypeTree for type trees).
-     *
-     *  Unfortunately `emptyValDef` is also considered to be `isEmpty`, but this is deemed to be
-     *  a conceptual mistake pending a fix in https://issues.scala-lang.org/browse/SI-6762.
      */
     def isEmpty: Boolean
 
@@ -2923,8 +2916,7 @@ trait Trees { self: Universe =>
       trees mapConserve (tree => transform(tree).asInstanceOf[TypeDef])
     /** Transforms a `ValDef`. */
     def transformValDef(tree: ValDef): ValDef =
-      if (tree eq emptyValDef) tree
-      else transform(tree).asInstanceOf[ValDef]
+      if (tree.isEmpty) tree else transform(tree).asInstanceOf[ValDef]
     /** Transforms a list of `ValDef` nodes. */
     def transformValDefs(trees: List[ValDef]): List[ValDef] =
       trees mapConserve (transformValDef(_))
diff --git a/src/reflect/scala/reflect/internal/Positions.scala b/src/reflect/scala/reflect/internal/Positions.scala
index f8c670827a..b65df0e70b 100644
--- a/src/reflect/scala/reflect/internal/Positions.scala
+++ b/src/reflect/scala/reflect/internal/Positions.scala
@@ -38,7 +38,7 @@ trait Positions extends api.Positions { self: SymbolTable =>
   protected class DefaultPosAssigner extends PosAssigner {
     var pos: Position = _
     override def traverse(t: Tree) {
-      if (!t.canHaveAttrs) ()
+      if (t.isDummy) ()
       else if (t.pos == NoPosition) {
         t.setPos(pos)
         super.traverse(t)   // TODO: bug? shouldn't the traverse be outside of the if?
diff --git a/src/reflect/scala/reflect/internal/Printers.scala b/src/reflect/scala/reflect/internal/Printers.scala
index a8085a4c58..6f834803c4 100644
--- a/src/reflect/scala/reflect/internal/Printers.scala
+++ b/src/reflect/scala/reflect/internal/Printers.scala
@@ -435,7 +435,7 @@ trait Printers extends api.Printers { self: SymbolTable =>
         case tree =>
           xprintTree(this, tree)
       }
-      if (printTypes && tree.isTerm && tree.canHaveAttrs) {
+      if (printTypes && tree.isTerm && !tree.isEmpty) {
         print("{", if (tree.tpe eq null) "<null>" else tree.tpe.toString, "}")
       }
     }
diff --git a/src/reflect/scala/reflect/internal/Trees.scala b/src/reflect/scala/reflect/internal/Trees.scala
index a528a9ced8..e586ab4cad 100644
--- a/src/reflect/scala/reflect/internal/Trees.scala
+++ b/src/reflect/scala/reflect/internal/Trees.scala
@@ -36,7 +36,7 @@ trait Trees extends api.Trees { self: SymbolTable =>
     def isDef = false
 
     def isEmpty = false
-    def canHaveAttrs = true
+    def isDummy = false
 
     /** The canonical way to test if a Tree represents a term.
      */
@@ -955,8 +955,9 @@ trait Trees extends api.Trees { self: SymbolTable =>
 
   def ValDef(sym: Symbol): ValDef = ValDef(sym, EmptyTree)
 
-  trait CannotHaveAttrs extends Tree {
-    override def canHaveAttrs = false
+  trait DummyTree extends Tree {
+    override def isEmpty = true
+    override def isDummy = true
 
     private def unsupported(what: String, args: Any*) =
       throw new UnsupportedOperationException(s"$what($args) inapplicable for "+self.toString)
@@ -968,9 +969,9 @@ trait Trees extends api.Trees { self: SymbolTable =>
     override def tpe_=(t: Type) = if (t != NoType) unsupported("tpe_=", t)
   }
 
-  case object EmptyTree extends TermTree with CannotHaveAttrs { override def isEmpty = true; val asList = List(this) }
-  object emptyValDef extends ValDef(Modifiers(PRIVATE), nme.WILDCARD, TypeTree(NoType), EmptyTree) with CannotHaveAttrs
-  object pendingSuperCall extends Apply(Select(Super(This(tpnme.EMPTY), tpnme.EMPTY), nme.CONSTRUCTOR), List()) with CannotHaveAttrs
+  case object EmptyTree extends TermTree with DummyTree { val asList = List(this) }
+  object emptyValDef extends ValDef(Modifiers(PRIVATE), nme.WILDCARD, TypeTree(NoType), EmptyTree) with DummyTree
+  object pendingSuperCall extends Apply(Select(Super(This(tpnme.EMPTY), tpnme.EMPTY), nme.CONSTRUCTOR), List()) with DummyTree
 
   def DefDef(sym: Symbol, mods: Modifiers, vparamss: List[List[ValDef]], rhs: Tree): DefDef =
     atPos(sym.pos) {
@@ -1122,7 +1123,7 @@ trait Trees extends api.Trees { self: SymbolTable =>
         traverse(annot); traverse(arg)
       case Template(parents, self, body) =>
         traverseTrees(parents)
-        if (self ne emptyValDef) traverse(self)
+        if (!self.isEmpty) traverse(self)
         traverseStats(body, tree.symbol)
       case Block(stats, expr) =>
         traverseTrees(stats); traverse(expr)
-- 
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