5 files changed, 16 insertions, 11 deletions
diff --git a/src/library/scala/xml/Elem.scala b/src/library/scala/xml/Elem.scala
index 127e6e0ab7..df52b34f87 100644
--- a/src/library/scala/xml/Elem.scala
+++ b/src/library/scala/xml/Elem.scala
@@ -41,7 +41,7 @@ object Elem {
 class Elem(
   override val prefix: String,
   val label: String,
-  override val attributes: MetaData,
+  attributes1: MetaData,
   override val scope: NamespaceBinding,
   val child: Node*)
 extends Node with Serializable
@@ -49,6 +49,8 @@ extends Node with Serializable
   final override def doCollectNamespaces = true
   final override def doTransform         = true
 
+  override val attributes = MetaData.normalize(attributes1, scope)
+
   if (prefix == "")
     throw new IllegalArgumentException("prefix of zero length, use null instead")
 
diff --git a/src/library/scala/xml/MetaData.scala b/src/library/scala/xml/MetaData.scala
index 98e863eb37..c516747bae 100644
--- a/src/library/scala/xml/MetaData.scala
+++ b/src/library/scala/xml/MetaData.scala
@@ -38,8 +38,8 @@ object MetaData {
     def iterate(md: MetaData, normalized_attribs: MetaData, set: Set[String]): MetaData = {
       lazy val key = getUniversalKey(md, scope)
       if (md eq Null) normalized_attribs
-      else if (set(key)) iterate(md.next, normalized_attribs, set)
-      else iterate(md.next, md copy normalized_attribs, set + key)
+      else if ((md.value eq null) || set(key)) iterate(md.next, normalized_attribs, set)
+      else md copy iterate(md.next, normalized_attribs, set + key)
     }
     iterate(attribs, Null, Set())
   }
diff --git a/src/library/scala/xml/PrefixedAttribute.scala b/src/library/scala/xml/PrefixedAttribute.scala
index 436dfcda43..b80d6a1c73 100644
--- a/src/library/scala/xml/PrefixedAttribute.scala
+++ b/src/library/scala/xml/PrefixedAttribute.scala
@@ -13,22 +13,25 @@ package scala.xml
  *
  *  @param pre   ...
  *  @param key   ...
- *  @param value the attribute value, which may not be null
+ *  @param value the attribute value
  *  @param next  ...
  */
 class PrefixedAttribute(
   val pre: String,
   val key: String,
   val value: Seq[Node],
-  val next: MetaData)
+  val next1: MetaData)
 extends Attribute
 {
-  if (value eq null)
-    throw new UnsupportedOperationException("value is null")
+  val next = if (value ne null) next1 else next1.remove(key)
 
-  /** same as this(key, Utility.parseAttributeValue(value), next) */
+  /** same as this(pre, key, Text(value), next), or no attribute if value is null */
   def this(pre: String, key: String, value: String, next: MetaData) =
-    this(pre, key, Text(value), next)
+    this(pre, key, if (value ne null) Text(value) else null: NodeSeq, next)
+
+  /** same as this(pre, key, value.get, next), or no attribute if value is None */
+  def this(pre: String, key: String, value: Option[Seq[Node]], next: MetaData) =
+    this(pre, key, value.orNull, next)
 
   /** Returns a copy of this unprefixed attribute with the given
    *  next field.
diff --git a/src/library/scala/xml/UnprefixedAttribute.scala b/src/library/scala/xml/UnprefixedAttribute.scala
index c56fba1e6c..b6800d5ed1 100644
--- a/src/library/scala/xml/UnprefixedAttribute.scala
+++ b/src/library/scala/xml/UnprefixedAttribute.scala
@@ -22,7 +22,7 @@ extends Attribute
   final val pre = null
   val next = if (value ne null) next1 else next1.remove(key)
 
-  /** same as this(key, Text(value), next) */
+  /** same as this(key, Text(value), next), or no attribute if value is null */
   def this(key: String, value: String, next: MetaData) =
     this(key, if (value ne null) Text(value) else null: NodeSeq, next)
 
diff --git a/src/library/scala/xml/Utility.scala b/src/library/scala/xml/Utility.scala
index 9b48f4e1bb..fc20b892b9 100644
--- a/src/library/scala/xml/Utility.scala
+++ b/src/library/scala/xml/Utility.scala
@@ -61,7 +61,7 @@ object Utility extends AnyRef with parsing.TokenTests {
     val key = md.key
     val smaller = sort(md.filter { m => m.key < key })
     val greater = sort(md.filter { m => m.key > key })
-    smaller.append( Null ).append(md.copy ( greater ))
+    smaller.copy(md.copy ( greater ))
   }
 
   /** Return the node with its attribute list sorted alphabetically