Merge pull request #4343 from adriaanm/reword-4267

SI-9113 Converting `null` collection Java<->Scala yields `null`

2 files changed, 55 insertions, 36 deletions

diff --git a/src/library/scala/collection/convert/WrapAsJava.scala b/src/library/scala/collection/convert/WrapAsJava.scala
index 9916fe9843..e97a2ff1fc 100644
--- a/src/library/scala/collection/convert/WrapAsJava.scala
+++ b/src/library/scala/collection/convert/WrapAsJava.scala
@@ -30,8 +30,9 @@ trait WrapAsJava {
    * @return    A Java Iterator view of the argument.
    */
   implicit def asJavaIterator[A](it: Iterator[A]): ju.Iterator[A] = it match {
-    case JIteratorWrapper(wrapped) => wrapped.asInstanceOf[ju.Iterator[A]]
-    case _ => IteratorWrapper(it)
+    case null                       => null
+    case JIteratorWrapper(wrapped)  => wrapped.asInstanceOf[ju.Iterator[A]]
+    case _                          => IteratorWrapper(it)
   }
 
   /**
@@ -48,8 +49,9 @@ trait WrapAsJava {
    * @return   A Java Enumeration view of the argument.
    */
   implicit def asJavaEnumeration[A](it: Iterator[A]): ju.Enumeration[A] = it match {
+    case null                         => null
     case JEnumerationWrapper(wrapped) => wrapped.asInstanceOf[ju.Enumeration[A]]
-    case _ => IteratorWrapper(it)
+    case _                            => IteratorWrapper(it)
   }
 
   /**
@@ -66,8 +68,9 @@ trait WrapAsJava {
    * @return A Java Iterable view of the argument.
    */
   implicit def asJavaIterable[A](i: Iterable[A]): jl.Iterable[A] = i match {
-    case JIterableWrapper(wrapped) => wrapped.asInstanceOf[jl.Iterable[A]]
-    case _ => IterableWrapper(i)
+    case null                       => null
+    case JIterableWrapper(wrapped)  => wrapped.asInstanceOf[jl.Iterable[A]]
+    case _                          => IterableWrapper(i)
   }
 
   /**
@@ -82,8 +85,9 @@ trait WrapAsJava {
    * @return   A Java Collection view of the argument.
    */
   implicit def asJavaCollection[A](it: Iterable[A]): ju.Collection[A] = it match {
-    case JCollectionWrapper(wrapped) => wrapped.asInstanceOf[ju.Collection[A]]
-    case _ => new IterableWrapper(it)
+    case null                         => null
+    case JCollectionWrapper(wrapped)  => wrapped.asInstanceOf[ju.Collection[A]]
+    case _                            => new IterableWrapper(it)
   }
 
   /**
@@ -100,8 +104,9 @@ trait WrapAsJava {
    * @return A Java List view of the argument.
    */
   implicit def bufferAsJavaList[A](b: mutable.Buffer[A]): ju.List[A] = b match {
-    case JListWrapper(wrapped) => wrapped
-    case _ => new MutableBufferWrapper(b)
+    case null                   => null
+    case JListWrapper(wrapped)  => wrapped
+    case _                      => new MutableBufferWrapper(b)
   }
 
   /**
@@ -118,8 +123,9 @@ trait WrapAsJava {
    * @return    A Java List view of the argument.
    */
   implicit def mutableSeqAsJavaList[A](seq: mutable.Seq[A]): ju.List[A] = seq match {
-    case JListWrapper(wrapped) => wrapped
-    case _ => new MutableSeqWrapper(seq)
+    case null                   => null
+    case JListWrapper(wrapped)  => wrapped
+    case _                      => new MutableSeqWrapper(seq)
   }
 
   /**
@@ -136,8 +142,9 @@ trait WrapAsJava {
    * @return    A Java List view of the argument.
    */
   implicit def seqAsJavaList[A](seq: Seq[A]): ju.List[A] = seq match {
-    case JListWrapper(wrapped) => wrapped.asInstanceOf[ju.List[A]]
-    case _ => new SeqWrapper(seq)
+    case null                   => null
+    case JListWrapper(wrapped)  => wrapped.asInstanceOf[ju.List[A]]
+    case _                      => new SeqWrapper(seq)
   }
 
   /**
@@ -154,8 +161,9 @@ trait WrapAsJava {
    * @return A Java Set view of the argument.
    */
   implicit def mutableSetAsJavaSet[A](s: mutable.Set[A]): ju.Set[A] = s match {
+    case null                 => null
     case JSetWrapper(wrapped) => wrapped
-    case _ => new MutableSetWrapper(s)
+    case _                    => new MutableSetWrapper(s)
   }
 
   /**
@@ -172,8 +180,9 @@ trait WrapAsJava {
    * @return A Java Set view of the argument.
    */
   implicit def setAsJavaSet[A](s: Set[A]): ju.Set[A] = s match {
+    case null                 => null
     case JSetWrapper(wrapped) => wrapped
-    case _ => new SetWrapper(s)
+    case _                    => new SetWrapper(s)
   }
 
   /**
@@ -190,9 +199,9 @@ trait WrapAsJava {
    * @return A Java Map view of the argument.
    */
   implicit def mutableMapAsJavaMap[A, B](m: mutable.Map[A, B]): ju.Map[A, B] = m match {
-    //case JConcurrentMapWrapper(wrapped) => wrapped
+    case null                 => null
     case JMapWrapper(wrapped) => wrapped
-    case _ => new MutableMapWrapper(m)
+    case _                    => new MutableMapWrapper(m)
   }
 
   /**
@@ -210,9 +219,9 @@ trait WrapAsJava {
    * @return A Java `Dictionary` view of the argument.
    */
   implicit def asJavaDictionary[A, B](m: mutable.Map[A, B]): ju.Dictionary[A, B] = m match {
-    //case JConcurrentMapWrapper(wrapped) => wrapped
-    case JDictionaryWrapper(wrapped) => wrapped
-    case _ => new DictionaryWrapper(m)
+    case null                         => null
+    case JDictionaryWrapper(wrapped)  => wrapped
+    case _                            => new DictionaryWrapper(m)
   }
 
   /**
@@ -230,9 +239,9 @@ trait WrapAsJava {
    * @return A Java `Map` view of the argument.
    */
   implicit def mapAsJavaMap[A, B](m: Map[A, B]): ju.Map[A, B] = m match {
-    //case JConcurrentMapWrapper(wrapped) => wrapped
+    case null                 => null
     case JMapWrapper(wrapped) => wrapped.asInstanceOf[ju.Map[A, B]]
-    case _ => new MapWrapper(m)
+    case _                    => new MapWrapper(m)
   }
 
   /**
@@ -251,8 +260,9 @@ trait WrapAsJava {
    * @return A Java `ConcurrentMap` view of the argument.
    */
   implicit def mapAsJavaConcurrentMap[A, B](m: concurrent.Map[A, B]): juc.ConcurrentMap[A, B] = m match {
+    case null                           => null
     case JConcurrentMapWrapper(wrapped) => wrapped
-    case _ => new ConcurrentMapWrapper(m)
+    case _                              => new ConcurrentMapWrapper(m)
   }
 }
 
diff --git a/src/library/scala/collection/convert/WrapAsScala.scala b/src/library/scala/collection/convert/WrapAsScala.scala
index ab151a6778..7332b71af1 100644
--- a/src/library/scala/collection/convert/WrapAsScala.scala
+++ b/src/library/scala/collection/convert/WrapAsScala.scala
@@ -30,8 +30,9 @@ trait WrapAsScala {
    * @return   A Scala `Iterator` view of the argument.
    */
   implicit def asScalaIterator[A](it: ju.Iterator[A]): Iterator[A] = it match {
+    case null                     => null
     case IteratorWrapper(wrapped) => wrapped
-    case _ => JIteratorWrapper(it)
+    case _                        => JIteratorWrapper(it)
   }
 
   /**
@@ -48,8 +49,9 @@ trait WrapAsScala {
    * @return A Scala Iterator view of the argument.
    */
   implicit def enumerationAsScalaIterator[A](i: ju.Enumeration[A]): Iterator[A] = i match {
+    case null                     => null
     case IteratorWrapper(wrapped) => wrapped
-    case _ => JEnumerationWrapper(i)
+    case _                        => JEnumerationWrapper(i)
   }
 
   /**
@@ -67,8 +69,9 @@ trait WrapAsScala {
    * @return A Scala Iterable view of the argument.
    */
   implicit def iterableAsScalaIterable[A](i: jl.Iterable[A]): Iterable[A] = i match {
+    case null                     => null
     case IterableWrapper(wrapped) => wrapped
-    case _ => JIterableWrapper(i)
+    case _                        => JIterableWrapper(i)
   }
 
   /**
@@ -82,8 +85,9 @@ trait WrapAsScala {
    * @return A Scala Iterable view of the argument.
    */
   implicit def collectionAsScalaIterable[A](i: ju.Collection[A]): Iterable[A] = i match {
+    case null                     => null
     case IterableWrapper(wrapped) => wrapped
-    case _ => JCollectionWrapper(i)
+    case _                        => JCollectionWrapper(i)
   }
 
   /**
@@ -101,8 +105,9 @@ trait WrapAsScala {
    * @return A Scala mutable `Buffer` view of the argument.
    */
   implicit def asScalaBuffer[A](l: ju.List[A]): mutable.Buffer[A] = l match {
-    case MutableBufferWrapper(wrapped) => wrapped
-    case _ =>new JListWrapper(l)
+    case null                           => null
+    case MutableBufferWrapper(wrapped)  => wrapped
+    case _                              => new JListWrapper(l)
   }
 
   /**
@@ -119,8 +124,9 @@ trait WrapAsScala {
    * @return A Scala mutable Set view of the argument.
    */
   implicit def asScalaSet[A](s: ju.Set[A]): mutable.Set[A] = s match {
+    case null                       => null
     case MutableSetWrapper(wrapped) => wrapped
-    case _ =>new JSetWrapper(s)
+    case _                          => new JSetWrapper(s)
   }
 
   /**
@@ -144,9 +150,9 @@ trait WrapAsScala {
    * @return A Scala mutable Map view of the argument.
    */
   implicit def mapAsScalaMap[A, B](m: ju.Map[A, B]): mutable.Map[A, B] = m match {
-    //case ConcurrentMapWrapper(wrapped) => wrapped
+    case null                       => null
     case MutableMapWrapper(wrapped) => wrapped
-    case _ => new JMapWrapper(m)
+    case _                          => new JMapWrapper(m)
   }
 
   /**
@@ -163,8 +169,9 @@ trait WrapAsScala {
    * @return A Scala mutable ConcurrentMap view of the argument.
    */
   implicit def mapAsScalaConcurrentMap[A, B](m: juc.ConcurrentMap[A, B]): concurrent.Map[A, B] = m match {
-    case cmw: ConcurrentMapWrapper[a, b]      => cmw.underlying
-    case _                                    => new JConcurrentMapWrapper(m)
+    case null                             => null
+    case cmw: ConcurrentMapWrapper[A, B]  => cmw.underlying
+    case _                                => new JConcurrentMapWrapper(m)
   }
 
   /**
@@ -179,8 +186,9 @@ trait WrapAsScala {
    * @return  A Scala mutable Map[String, String] view of the argument.
    */
   implicit def dictionaryAsScalaMap[A, B](p: ju.Dictionary[A, B]): mutable.Map[A, B] = p match {
+    case null                       => null
     case DictionaryWrapper(wrapped) => wrapped
-    case _ => new JDictionaryWrapper(p)
+    case _                          => new JDictionaryWrapper(p)
   }
 
   /**
@@ -194,7 +202,8 @@ trait WrapAsScala {
    * @return  A Scala mutable Map[String, String] view of the argument.
    */
   implicit def propertiesAsScalaMap(p: ju.Properties): mutable.Map[String, String] = p match {
-    case _ => new JPropertiesWrapper(p)
+    case null => null
+    case _    => new JPropertiesWrapper(p)
   }
 }