Replaced == null()eq null(ne null)

103 files changed, 443 insertions, 444 deletions

diff --git a/src/actors/scala/actors/Actor.scala b/src/actors/scala/actors/Actor.scala
index af2b477ccf..419f7f30fb 100644
--- a/src/actors/scala/actors/Actor.scala
+++ b/src/actors/scala/actors/Actor.scala
@@ -36,7 +36,7 @@ object Actor {
   def self: Actor = synchronized {
     val t = currentThread
     var a = selfs.get(t).asInstanceOf[Actor]
-    if (a == null) {
+    if (a eq null) {
       a = new ActorProxy(t)
       selfs.put(t, a)
     }
@@ -303,7 +303,7 @@ trait Actor extends OutputChannel[Any] {
   private var rc: Channel[Any] = null
 
   private[actors] def reply: Channel[Any] = {
-    if (rc == null) {
+    if (rc eq null) {
       rc = new Channel[Any]
       rc.receiver = this
     }
@@ -350,12 +350,12 @@ trait Actor extends OutputChannel[Any] {
   private[actors] var timeoutPending = false
 
   private[actors] def scheduleActor(f: PartialFunction[Any, Unit], msg: Any) =
-    if (f == null && continuation == null) {
+    if ((f eq null) && (continuation eq null)) {
       // do nothing (timeout is handled instead)
     }
     else {
       val task = new ActorTask(this,
-                               if (f == null) continuation else f,
+                               if (f eq null) continuation else f,
                                msg)
       Scheduler.execute(task)
     }
diff --git a/src/actors/scala/actors/Channel.scala b/src/actors/scala/actors/Channel.scala
index 20e1cd0f49..85949db53a 100644
--- a/src/actors/scala/actors/Channel.scala
+++ b/src/actors/scala/actors/Channel.scala
@@ -50,7 +50,7 @@ class Channel[Msg] extends InputChannel[Msg] with OutputChannel[Msg] {
 
   private def send(msg: Msg, sender: Actor) = receiver.synchronized {
     receiver.tick()
-    if (waitingFor(msg) && ((waitingForSender == null) ||
+    if (waitingFor(msg) && ((waitingForSender eq null) ||
         (waitingForSender == sender))) {
       received = msg
       receiver.pushSender(sender)
@@ -215,7 +215,7 @@ class Channel[Msg] extends InputChannel[Msg] with OutputChannel[Msg] {
       else synchronized {
         isSuspended = true
         receiver.suspendActorFor(msec)
-        if (received == null)
+        if (received eq null)
           if (f.isDefinedAt(TIMEOUT)) {
             isSuspended = false
             val result = f(TIMEOUT)
@@ -240,7 +240,7 @@ class Channel[Msg] extends InputChannel[Msg] with OutputChannel[Msg] {
             received = null
             receiver.suspendActorFor(msec)
             Debug.info("received: "+received)
-            if (received == null) {
+            if (received eq null) {
               Debug.info("no message received after "+msec+" millis")
               if (f.isDefinedAt(TIMEOUT)) {
                 Debug.info("executing TIMEOUT action")
diff --git a/src/actors/scala/actors/Scheduler.scala b/src/actors/scala/actors/Scheduler.scala
index 50d7a2db39..314f1e2311 100644
--- a/src/actors/scala/actors/Scheduler.scala
+++ b/src/actors/scala/actors/Scheduler.scala
@@ -372,7 +372,7 @@ class QuitException extends Throwable {
  * <p>
  *   A worker thread enters the idle queue of the scheduler when
  *   <code>getTask</code> returns <code>null</code>. Then it will also stay
- *   in the while-loop W (<code>while (task == null)</code>) until
+ *   in the while-loop W (<code>while (task eq null)</code>) until
  *   <code>task</code> becomes non-null. The only way this can happen is
  *   through a call of <code>execute</code> by the scheduler. Before every
  *   call of <code>execute</code> the worker thread is removed from the idle
@@ -401,7 +401,7 @@ class WorkerThread(sched: IScheduler) extends Thread {
   override def run(): Unit =
     try {
       while (running) {
-        if (task != null) {
+        if (task ne null) {
           try {
             task.run()
           } catch {
@@ -412,7 +412,7 @@ class WorkerThread(sched: IScheduler) extends Thread {
         this.synchronized {
           task = sched.getTask(this)
 
-          while (task == null) {
+          while (task eq null) {
             try {
               wait()
             } catch {
diff --git a/src/compiler/scala/tools/ant/FastScalac.scala b/src/compiler/scala/tools/ant/FastScalac.scala
index 68c7acc48f..8b64cb2be9 100644
--- a/src/compiler/scala/tools/ant/FastScalac.scala
+++ b/src/compiler/scala/tools/ant/FastScalac.scala
@@ -98,7 +98,7 @@ package scala.tools.ant {
         try {
           nsc.CompileClient.main0(args)
         } catch {
-          case exception: Throwable if (exception.getMessage != null) =>
+          case exception: Throwable if (exception.getMessage ne null) =>
             exception.printStackTrace()
             error("Compile failed because of an internal compiler error (" +
               exception.getMessage + "); see the error output for details.")
diff --git a/src/compiler/scala/tools/ant/Scalac.scala b/src/compiler/scala/tools/ant/Scalac.scala
index efb19021e5..4957eb088a 100644
--- a/src/compiler/scala/tools/ant/Scalac.scala
+++ b/src/compiler/scala/tools/ant/Scalac.scala
@@ -591,7 +591,7 @@ package scala.tools.ant {
       try {
         (new compiler.Run).compile(sourceFiles.map (.toString()))
        } catch {
-        case exception: Throwable if (exception.getMessage != null) =>
+        case exception: Throwable if (exception.getMessage ne null) =>
           exception.printStackTrace()
           error("Compile failed because of an internal compiler error (" +
             exception.getMessage + "); see the error output for details.")
diff --git a/src/compiler/scala/tools/ant/Scaladoc.scala b/src/compiler/scala/tools/ant/Scaladoc.scala
index 9d58b84f4c..08c75c1adb 100644
--- a/src/compiler/scala/tools/ant/Scaladoc.scala
+++ b/src/compiler/scala/tools/ant/Scaladoc.scala
@@ -465,7 +465,7 @@ package scala.tools.ant {
             "; see the documenter output for details.")
         reporter.printSummary()
       } catch {
-        case exception: Throwable if (exception.getMessage != null) =>
+        case exception: Throwable if (exception.getMessage ne null) =>
           exception.printStackTrace()
           error("Document failed because of an internal documenter error (" +
             exception.getMessage + "); see the error output for details.")
diff --git a/src/compiler/scala/tools/nsc/CompileClient.scala b/src/compiler/scala/tools/nsc/CompileClient.scala
index facfca7768..970becc5f5 100644
--- a/src/compiler/scala/tools/nsc/CompileClient.scala
+++ b/src/compiler/scala/tools/nsc/CompileClient.scala
@@ -98,7 +98,7 @@ object CompileClient {
     out.println(args.mkString("", "\0", ""))
     var sawerror = false
     var fromServer = in.readLine()
-    while (fromServer != null) {
+    while (fromServer ne null) {
       if (CompileSocket.errorPattern.matcher(fromServer).matches)
         sawerror = true
       Console.println(fromServer)
diff --git a/src/compiler/scala/tools/nsc/CompileServer.scala b/src/compiler/scala/tools/nsc/CompileServer.scala
index d407dd111a..48f30041a7 100644
--- a/src/compiler/scala/tools/nsc/CompileServer.scala
+++ b/src/compiler/scala/tools/nsc/CompileServer.scala
@@ -79,7 +79,7 @@ object CompileServer extends SocketServer {
     val password = CompileSocket.getPassword(port)
     val guessedPassword = in.readLine()
     val input = in.readLine()
-    if (input != null && password == guessedPassword) {
+    if ((input ne null) && password == guessedPassword) {
       try {
         inSession = true
         progress = true
@@ -121,7 +121,7 @@ object CompileServer extends SocketServer {
           reporter.info(null, command.usageMsg, true)
         else {
           try {
-            if (compiler != null && settingsAreCompatible(command.settings, compiler.settings)) {
+            if ((compiler ne null) && settingsAreCompatible(command.settings, compiler.settings)) {
               compiler.settings = command.settings
               compiler.reporter = reporter
             } else {
diff --git a/src/compiler/scala/tools/nsc/CompileSocket.scala b/src/compiler/scala/tools/nsc/CompileSocket.scala
index d326aa433f..f52777ed63 100644
--- a/src/compiler/scala/tools/nsc/CompileSocket.scala
+++ b/src/compiler/scala/tools/nsc/CompileSocket.scala
@@ -62,7 +62,7 @@ object CompileSocket {
     def expand(trial: Pair[String, List[String]]): Option[File] = {
       val Pair(topdirProp, extensions) = trial
       val topdir = System.getProperty(topdirProp)
-      if (topdir == null)
+      if (topdir eq null)
         return None
 
       val fulldir =
diff --git a/src/compiler/scala/tools/nsc/EvalLoop.scala b/src/compiler/scala/tools/nsc/EvalLoop.scala
index 24b5ef9bb2..25f34e4e8d 100644
--- a/src/compiler/scala/tools/nsc/EvalLoop.scala
+++ b/src/compiler/scala/tools/nsc/EvalLoop.scala
@@ -13,7 +13,7 @@ trait EvalLoop {
   def loop(action: (String) => Unit): Unit = {
     Console.print(prompt)
     val line = Console.readLine
-    if (line != null && line.length() > 0) {
+    if ((line ne null) && line.length() > 0) {
       action(line)
       loop(action)
     }
diff --git a/src/compiler/scala/tools/nsc/Global.scala b/src/compiler/scala/tools/nsc/Global.scala
index 082f5cc910..7e88d0dd13 100644
--- a/src/compiler/scala/tools/nsc/Global.scala
+++ b/src/compiler/scala/tools/nsc/Global.scala
@@ -175,7 +175,7 @@ class Global(var settings: Settings, var reporter: Reporter) extends SymbolTable
 
   def getSourceFile(name: String): SourceFile = {
     val f = AbstractFile.getFile(name)
-    if (f == null) throw new FileNotFoundException(
+    if (f eq null) throw new FileNotFoundException(
       "source file '" + name + "' could not be found")
     getSourceFile(f)
   }
@@ -509,7 +509,7 @@ class Global(var settings: Settings, var reporter: Reporter) extends SymbolTable
     }
 
     def compileLate(file: AbstractFile): unit =
-      if (fileset == null) {
+      if (fileset eq null) {
         val msg = "No class file for " + file +
                   " was found\n(This file cannot be loaded as a source file)"
         inform(msg)
diff --git a/src/compiler/scala/tools/nsc/Interpreter.scala b/src/compiler/scala/tools/nsc/Interpreter.scala
index 836512bae0..bdfcae0042 100644
--- a/src/compiler/scala/tools/nsc/Interpreter.scala
+++ b/src/compiler/scala/tools/nsc/Interpreter.scala
@@ -107,7 +107,7 @@ class Interpreter(val settings: Settings, reporter: Reporter, out: PrintWriter)
          definitions.
   */
   private val classLoader =
-    if (parentClassLoader == null)
+    if (parentClassLoader eq null)
       new URLClassLoader(Array(classfilePath.toURL))
     else
       new URLClassLoader(Array(classfilePath.toURL), parentClassLoader)
@@ -277,7 +277,7 @@ class Interpreter(val settings: Settings, reporter: Reporter, out: PrintWriter)
 
     // figure out what kind of request
     val req = buildRequest(trees, line, lineName)
-    if (req == null) return false  // a disallowed statement type
+    if (req eq null) return false  // a disallowed statement type
 
     if (!req.compile)
       return false  // an error happened during compilation, e.g. a type error
@@ -571,7 +571,7 @@ class Interpreter(val settings: Settings, reporter: Reporter, out: PrintWriter)
       } catch {
         case e => {
           def caus(e: Throwable): Throwable =
-            if (e.getCause == null) e else caus(e.getCause)
+            if (e.getCause eq null) e else caus(e.getCause)
             val orig = caus(e)
             Pair(stringFrom(str => orig.printStackTrace(str)),
                  false)
diff --git a/src/compiler/scala/tools/nsc/InterpreterLoop.scala b/src/compiler/scala/tools/nsc/InterpreterLoop.scala
index be37fd9735..9416aee401 100644
--- a/src/compiler/scala/tools/nsc/InterpreterLoop.scala
+++ b/src/compiler/scala/tools/nsc/InterpreterLoop.scala
@@ -42,7 +42,7 @@ class InterpreterLoop(in: BufferedReader, out: PrintWriter) {
   /** Close the interpreter, if there is one, and set
     * interpreter to null. */
   def closeInterpreter =
-    if (interpreter != null) {
+    if (interpreter ne null) {
       interpreter.close
       interpreter = null
     }
@@ -83,7 +83,7 @@ class InterpreterLoop(in: BufferedReader, out: PrintWriter) {
       out.print("\nscala> ")
       out.flush
       var line = in.readLine()
-      if (line == null)
+      if (line eq null)
         return ()  // assumes null means EOF
 
       val Pair(keepGoing, shouldReplay) = command(line)
@@ -103,11 +103,11 @@ class InterpreterLoop(in: BufferedReader, out: PrintWriter) {
         out.println("Error opening file: " + filename)
         null
     }
-    if (fileIn == null) return ()
+    if (fileIn eq null) return ()
     val in = new BufferedReader(fileIn)
     while (true) {
       val line = in.readLine
-      if (line == null) {
+      if (line eq null) {
         fileIn.close
         return ()
       }
diff --git a/src/compiler/scala/tools/nsc/MainGenericRunner.scala b/src/compiler/scala/tools/nsc/MainGenericRunner.scala
index 1a8a3e02b9..ef70977a86 100644
--- a/src/compiler/scala/tools/nsc/MainGenericRunner.scala
+++ b/src/compiler/scala/tools/nsc/MainGenericRunner.scala
@@ -23,7 +23,7 @@ object MainGenericRunner {
     */
   def addClasspathExtras(classpath: String): String = {
     val scalaHome = getProperty("scala.home")
-    if (scalaHome == null)
+    if (scalaHome eq null)
       return classpath
 
     val libdir = new File(new File(scalaHome), "lib")
diff --git a/src/compiler/scala/tools/nsc/Phase.scala b/src/compiler/scala/tools/nsc/Phase.scala
index a27c71f961..a66cdecfde 100644
--- a/src/compiler/scala/tools/nsc/Phase.scala
+++ b/src/compiler/scala/tools/nsc/Phase.scala
@@ -12,15 +12,15 @@ abstract class Phase(val prev: Phase) {
 
   type Id = int
 
-  val id: Id = if (prev == null) 0 else prev.id + 1
+  val id: Id = if (prev eq null) 0 else prev.id + 1
 
   def newFlags: long = 0l
   private var fmask: long =
-    if (prev == null) Flags.InitialFlags else prev.flagMask | newFlags
+    if (prev eq null) Flags.InitialFlags else prev.flagMask | newFlags
   def flagMask: long = fmask
 
   private var nx: Phase = this
-  if (prev != null) prev.nx = this
+  if (prev ne null) prev.nx = this
 
   def next: Phase = nx
 
diff --git a/src/compiler/scala/tools/nsc/ScriptRunner.scala b/src/compiler/scala/tools/nsc/ScriptRunner.scala
index c0b92195f3..5e509959c2 100644
--- a/src/compiler/scala/tools/nsc/ScriptRunner.scala
+++ b/src/compiler/scala/tools/nsc/ScriptRunner.scala
@@ -199,7 +199,7 @@ object ScriptRunner {
     var compok = true
 
     var fromServer = in.readLine()
-    while (fromServer != null) {
+    while (fromServer ne null) {
       Console.println(fromServer)
       if (CompileSocket.errorPattern.matcher(fromServer).matches)
         compok = false
diff --git a/src/compiler/scala/tools/nsc/Settings.scala b/src/compiler/scala/tools/nsc/Settings.scala
index c67dfeb272..b4b9f02efc 100644
--- a/src/compiler/scala/tools/nsc/Settings.scala
+++ b/src/compiler/scala/tools/nsc/Settings.scala
@@ -19,7 +19,7 @@ class Settings(error: String => unit) {
     else null
 
   private val classpathDefault =
-    if (System.getProperty("env.classpath") != null)
+    if (System.getProperty("env.classpath") ne null)
       alternatePath(
         getProperty("env.classpath"),
         ".")
@@ -40,16 +40,16 @@ class Settings(error: String => unit) {
       "")
 
   private def alternatePath(p1: String, p2: => String) =
-    if (p1 != null) p1 else p2
+    if (p1 ne null) p1 else p2
 
   private def concatPath(p1: String, p2: String) =
-     if (p1 != null && p2 != null) p1 + File.pathSeparator + p2
-     else if (p1 != null) p1
+     if ((p1 ne null) && (p2 ne null)) p1 + File.pathSeparator + p2
+     else if (p1 ne null) p1
      else p2
 
   private def guessedScalaBootClassPath = {
     val scalaHome = System.getProperty("scala.home")
-    if (scalaHome != null) {
+    if (scalaHome ne null) {
       val guessJar = new File(new File(new File(scalaHome), "lib"), "scala-library.jar")
       if (guessJar.exists()) guessJar.getPath()
       else {
@@ -61,7 +61,7 @@ class Settings(error: String => unit) {
 
   private def guessedScalaExtDirs = {
     val scalaHome = System.getProperty("scala.home")
-    if (scalaHome != null) {
+    if (scalaHome ne null) {
       val guess = new File(new File(scalaHome), "lib")
       if (guess.exists()) guess.getPath else null
     } else null
diff --git a/src/compiler/scala/tools/nsc/ast/TreeBrowsers.scala b/src/compiler/scala/tools/nsc/ast/TreeBrowsers.scala
index cf3d9f8809..e645bf1ff1 100644
--- a/src/compiler/scala/tools/nsc/ast/TreeBrowsers.scala
+++ b/src/compiler/scala/tools/nsc/ast/TreeBrowsers.scala
@@ -229,7 +229,7 @@ abstract class TreeBrowsers {
           TreeInfo.symbolTypeDoc(t).format(getWidth() / getColumnWidth(), buf)
           str.append(buf.toString())
           str.append("\nSymbol tpe: ")
-          if (t.symbol != null) {
+          if (t.symbol ne null) {
             str.append(t.symbol.tpe).append("\n");
             buf = new StringWriter();
             TypePrinter.toDocument(t.symbol.tpe).format(getWidth() / getColumnWidth(), buf)
@@ -534,7 +534,7 @@ abstract class TreeBrowsers {
     /** Return t's symbol type  */
     def symbolTypeDoc(t: Tree): Document = {
       val s = t.symbol
-      if (s != null)
+      if (s ne null)
         TypePrinter.toDocument(s.info)
       else
         DocNil
@@ -546,7 +546,7 @@ abstract class TreeBrowsers {
       val s = t.symbol
       var att = ""
 
-      if (s != null) {
+      if (s ne null) {
         var str = flagsToString(s.flags)
         if (s.hasFlag(STATIC) || s.hasFlag(STATICMEMBER))
           str = str + " isStatic ";
diff --git a/src/compiler/scala/tools/nsc/ast/TreeGen.scala b/src/compiler/scala/tools/nsc/ast/TreeGen.scala
index 96110f8dc1..8be11e40b4 100644
--- a/src/compiler/scala/tools/nsc/ast/TreeGen.scala
+++ b/src/compiler/scala/tools/nsc/ast/TreeGen.scala
@@ -73,8 +73,8 @@ abstract class TreeGen {
       if (tree.symbol.isStable) tree.setType(singleType(tree.symbol.owner.thisType, tree.symbol))
       else tree
     case Select(qual, _) =>
-      assert(tree.symbol != null)
-      assert(qual.tpe != null)
+      assert(tree.symbol ne null)
+      assert(qual.tpe ne null)
       if (tree.symbol.isStable && qual.tpe.isStable)
         tree.setType(singleType(qual.tpe, tree.symbol))
       else tree
@@ -109,14 +109,14 @@ abstract class TreeGen {
   }
 
   def mkAttributedSelect(qual: Tree, sym: Symbol): Tree =
-    if (qual.symbol != null &&
+    if ((qual.symbol ne null) &&
         (qual.symbol.name.toTermName == nme.ROOT ||
          qual.symbol.name.toTermName == nme.EMPTY_PACKAGE_NAME)) {
       mkAttributedIdent(sym)
     } else {
       assert(sym.isTerm)
       val result = Select(qual, sym.name) setSymbol sym
-      if (qual.tpe != null) result setType qual.tpe.memberType(sym)
+      if (qual.tpe ne null) result setType qual.tpe.memberType(sym)
       result
     }
 
@@ -190,7 +190,7 @@ abstract class TreeGen {
     ValDef(mvar, if (mvar.owner.isClass) EmptyTree else Literal(Constant(null)))
   }
 
-  // def m: T = { if (m$ == null) m$ = new m$class; m$ }
+  // def m: T = { if (m$ eq null) m$ = new m$class; m$ }
   def mkModuleAccessDef(accessor: Symbol, mvar: Symbol) =
     DefDef(accessor, vparamss =>
       mkCached(mvar,
diff --git a/src/compiler/scala/tools/nsc/ast/TreeInfo.scala b/src/compiler/scala/tools/nsc/ast/TreeInfo.scala
index 4ac7646e4a..5b4622a984 100644
--- a/src/compiler/scala/tools/nsc/ast/TreeInfo.scala
+++ b/src/compiler/scala/tools/nsc/ast/TreeInfo.scala
@@ -206,7 +206,7 @@ abstract class TreeInfo {
    */
   def isSequencePattern(tree: Tree): boolean = tree match {
     case Apply(fn, _) =>
-      fn.symbol != null &&
+      (fn.symbol ne null) &&
       !fn.symbol.hasFlag(CASE) &&
       fn.symbol.isNonBottomSubClass(definitions.SeqClass)
     case Bind(name, body) =>
diff --git a/src/compiler/scala/tools/nsc/ast/TreePrinters.scala b/src/compiler/scala/tools/nsc/ast/TreePrinters.scala
index 237dbf8b46..3ac528844e 100644
--- a/src/compiler/scala/tools/nsc/ast/TreePrinters.scala
+++ b/src/compiler/scala/tools/nsc/ast/TreePrinters.scala
@@ -296,9 +296,9 @@ abstract class TreePrinters {
 
         case TypeTree() =>
           print(
-            if (tree.tpe == null)
+            if (tree.tpe eq null)
               "<type ?>"
-            else if (tree.tpe.symbol != null && tree.tpe.symbol.isAnonymousClass)
+            else if ((tree.tpe.symbol ne null) && tree.tpe.symbol.isAnonymousClass)
               tree.tpe.symbol.toString()
             else
               tree.tpe.toString()
@@ -318,10 +318,10 @@ abstract class TreePrinters {
 
         case WildcardTypeTree(lo, hi) =>
           print("_ "); printOpt(" >: ", lo); printOpt(" <: ", hi)
-        case tree if (tree != null) => print(tree.toString())
+        case tree if (tree ne null) => print(tree.toString())
       }
       if (global.settings.printtypes.value && tree.isTerm && !tree.isEmpty) {
-        print("{"); print(if (tree.tpe == null) "<null>" else tree.tpe.toString()); print("}")
+        print("{"); print(if (tree.tpe eq null) "<null>" else tree.tpe.toString()); print("}")
       }
     }
 
@@ -343,7 +343,7 @@ abstract class TreePrinters {
 
     def print(unit: CompilationUnit): unit = {
       print("// Scala source: " + unit.source + LINE_SEPARATOR)
-      if (unit.body != null) {
+      if (unit.body ne null) {
         print(unit.body); println
       } else {
         print("<null>")
diff --git a/src/compiler/scala/tools/nsc/ast/Trees.scala b/src/compiler/scala/tools/nsc/ast/Trees.scala
index 1958099e31..7e58592361 100644
--- a/src/compiler/scala/tools/nsc/ast/Trees.scala
+++ b/src/compiler/scala/tools/nsc/ast/Trees.scala
@@ -76,7 +76,7 @@ trait Trees requires Global {
     def isType = false
     def isEmpty = false
 
-    def isErroneous = tpe != null && tpe.isErroneous
+    def isErroneous = (tpe ne null) && tpe.isErroneous
 
     override def toString(): String = {
       val buffer = new StringWriter()
@@ -93,7 +93,7 @@ trait Trees requires Global {
     }
 
     def equalsStructure(that: Tree): Boolean = if (this == that) true else (this:Any) match {
-      case thiz : Product if (that != null && thiz.getClass == that.getClass) =>
+      case thiz : Product if ((that ne null) && thiz.getClass == that.getClass) =>
         val that0 = that.asInstanceOf[Product]
         val result: Iterator[Boolean] =
           for (val i <- 0.until(thiz.arity)) yield thiz.element(i) match {
@@ -103,7 +103,7 @@ trait Trees requires Global {
             case list: List[_] if (that0.element(i).isInstanceOf[List[Any]]) =>
               val listThat = that0.element(i).asInstanceOf[List[Any]]
               if (list.length == listThat.length) (for (val x <- list.zip(listThat)) yield {
-                if (x._1 != null && x._1.isInstanceOf[Tree] && x._2.isInstanceOf[Tree]) {
+                if ((null != x._1) && x._1.isInstanceOf[Tree] && x._2.isInstanceOf[Tree]) {
                   val b = x._1.asInstanceOf[Tree] equalsStructure x._2.asInstanceOf[Tree]
                   b
                 } else x._1 == x._2
@@ -610,7 +610,7 @@ trait Trees requires Global {
   /** Literal */
   case class Literal(value: Constant)
         extends TermTree {
-    assert(value != null)
+    assert(value ne null)
   }
 
   def Literal(value: Any): Literal =
@@ -624,7 +624,7 @@ trait Trees requires Global {
       original = tree
       setPos(tree.pos)
     }
-    override def isEmpty = tpe == null || tpe == NoType
+    override def isEmpty = (tpe eq null) || tpe == NoType
   }
 
   def TypeTree(tp: Type): TypeTree = TypeTree() setType tp
@@ -1328,7 +1328,7 @@ trait Trees requires Global {
   class TreeTypeSubstituter(from: List[Symbol], to: List[Type]) extends Traverser {
     val typeSubst = new SubstTypeMap(from, to)
     override def traverse(tree: Tree): unit = {
-      if (tree.tpe != null) tree.tpe = typeSubst(tree.tpe)
+      if (tree.tpe ne null) tree.tpe = typeSubst(tree.tpe)
       super.traverse(tree)
     }
     override def apply[T <: Tree](tree: T): T = super.apply(tree.duplicate)
@@ -1342,7 +1342,7 @@ trait Trees requires Global {
           if (tree.symbol == from.head) tree setSymbol to.head
           else subst(from.tail, to.tail)
       }
-      if (tree.tpe != null) tree.tpe = symSubst(tree.tpe)
+      if (tree.tpe ne null) tree.tpe = symSubst(tree.tpe)
       if (tree.hasSymbol) subst(from, to)
       super.traverse(tree)
     }
diff --git a/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala b/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
index 926ec36bf8..7a175d7c8c 100644
--- a/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
+++ b/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
@@ -196,7 +196,7 @@ trait Parsers requires SyntaxAnalyzer {
     */
     def joinComment(trees: => List[Tree]): List[Tree] = {
       val buf = in.docBuffer
-      if (buf != null) {
+      if (buf ne null) {
         in.docBuffer = null
         trees map (t => DocDef(buf.toString(), t) setPos t.pos)
       } else trees
@@ -1440,7 +1440,7 @@ trait Parsers requires SyntaxAnalyzer {
         }
         val pname = ident()
         val param = atPos(in.currentPos) { typeBounds(mods, pname) }
-        if (in.token == VIEWBOUND && (implicitViews != null))
+        if (in.token == VIEWBOUND && (implicitViews ne null))
           implicitViews += atPos(in.skipToken()) {
             makeFunctionTypeTree(List(Ident(pname.toTypeName)), typ())
           }
diff --git a/src/compiler/scala/tools/nsc/ast/parser/Scanners.scala b/src/compiler/scala/tools/nsc/ast/parser/Scanners.scala
index 35f4c7b404..8004976cf5 100644
--- a/src/compiler/scala/tools/nsc/ast/parser/Scanners.scala
+++ b/src/compiler/scala/tools/nsc/ast/parser/Scanners.scala
@@ -81,7 +81,7 @@ trait Scanners requires SyntaxAnalyzer {
     /** add the given character to the documentation buffer
      */
     protected def putDocChar(c: char): unit =
-      if (docBuffer != null) docBuffer.append(c)
+      if (docBuffer ne null) docBuffer.append(c)
 
     /** we need one token lookahead
      */
@@ -883,7 +883,7 @@ trait Scanners requires SyntaxAnalyzer {
       for (val i <- 0 to maxKey)
         key(i) = IDENTIFIER
       for (val j <- 0 until tokenCount)
-        if (tokenName(j) != null)
+        if (tokenName(j) ne null)
           key(tokenName(j).start) = j.asInstanceOf[byte]
 
     }
diff --git a/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala b/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala
index b3bdcce65f..00a1cc4c95 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala
@@ -324,8 +324,7 @@ trait BasicBlocks requires ICodes {
      *  in different code 'chunks' than the rest of the method.
      */
     def predecessors: List[BasicBlock] = {
-//      if (preds == null)
-        preds = code.blocks.elements.filter (p => (p.successors contains this)).toList;
+      preds = code.blocks.elements.filter (.successors.contains(this)).toList;
       preds
     }
 
diff --git a/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala b/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala
index b1e2912e33..4ecd9c7012 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala
@@ -1254,7 +1254,7 @@ abstract class GenICode extends SubComponent  {
             case Pair(expr, Literal(Constant(null))) => expr
             case _ => null
           }
-          if (expr != null) {
+          if (expr ne null) {
             val ctx1 = genLoad(expr, ctx, ANY_REF_CLASS)
             if (code == scalaPrimitives.ID)
               ctx1.bb.emit(CZJUMP(thenCtx.bb, elseCtx.bb, EQ, ANY_REF_CLASS))
@@ -1344,7 +1344,7 @@ abstract class GenICode extends SubComponent  {
 
     /**
      * Generate the "==" code for object references. It is equivalent of
-     * if (l == null) then r == null else l.equals(r);
+     * if (l eq null) then r eq null else l.equals(r);
      *
      * @param l       ...
      * @param r       ...
@@ -1361,7 +1361,7 @@ abstract class GenICode extends SubComponent  {
         case Pair(expr, Literal(Constant(null))) => expr
         case _ => null
       }
-      if (expr != null) {
+      if (expr ne null) {
         val ctx1 = genLoad(expr, ctx, ANY_REF_CLASS)
         ctx1.bb.emit(CZJUMP(thenCtx.bb, elseCtx.bb, EQ, ANY_REF_CLASS))
         ctx1.bb.close
@@ -1799,7 +1799,7 @@ abstract class GenICode extends SubComponent  {
       }
 
       def setParams(p: List[Symbol]): Label = {
-        assert(params == null, "Cannot set label parameters twice!")
+        assert(params eq null, "Cannot set label parameters twice!")
         params = p
         this
       }
diff --git a/src/compiler/scala/tools/nsc/backend/icode/TypeKinds.scala b/src/compiler/scala/tools/nsc/backend/icode/TypeKinds.scala
index 3374696765..e06fd5e2e4 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/TypeKinds.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/TypeKinds.scala
@@ -211,7 +211,7 @@ trait TypeKinds requires ICodes {
 
   /** A class type. */
   case class REFERENCE(cls: Symbol) extends TypeKind {
-    assert(cls != null,
+    assert(cls ne null,
            "REFERENCE to null class symbol.")
     assert(cls != definitions.ArrayClass,
            "REFERENCE to Array is not allowed, should be ARRAY[..] instead")
diff --git a/src/compiler/scala/tools/nsc/backend/jvm/GenJVM.scala b/src/compiler/scala/tools/nsc/backend/jvm/GenJVM.scala
index 946a4a550e..979ed831c9 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/GenJVM.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/GenJVM.scala
@@ -125,7 +125,7 @@ abstract class GenJVM extends SubComponent {
       jclass.writeTo(outfile)
       val file = scala.tools.nsc.io.AbstractFile.getFile(outfile)
       informProgress("wrote " + outfile + " " +
-                     (if (file != null) "" + file.file + " " + file.file.exists()
+                     (if (file ne null) "" + file.file + " " + file.file.exists()
                       else "no file"))
     }
 
diff --git a/src/compiler/scala/tools/nsc/doc/DocGenerator.scala b/src/compiler/scala/tools/nsc/doc/DocGenerator.scala
index 72dab71d7f..8b1bcb17b1 100644
--- a/src/compiler/scala/tools/nsc/doc/DocGenerator.scala
+++ b/src/compiler/scala/tools/nsc/doc/DocGenerator.scala
@@ -40,7 +40,7 @@ abstract class DocGenerator extends Models {
   abstract class Frame extends UrlContext {
     def path: String // relative to outdir
     def relative: String = {
-      assert(path != null)
+      assert(path ne null)
       var idx = 0
       var ct = new StringBuilder
       while (idx != -1) {
@@ -76,7 +76,7 @@ abstract class DocGenerator extends Models {
       val sym = tree.symbol
       if (sym == NoSymbol)
         Text(tree.asInstanceOf[ValOrDefDef].name.toString())
-      else if (sym.sourceFile == null)
+      else if (sym.sourceFile eq null)
         Text(sym.fullNameString('.'))
       else
         aref(urlFor(sym), target, sym.nameString)
@@ -92,11 +92,11 @@ abstract class DocGenerator extends Models {
      *  @return       ...
      */
     def urlFor(tpe: Type, target: String): NodeSeq = try {
-      if (tpe.symbol.hasFlag(Flags.JAVA) || tpe.symbol.sourceFile == null)
+      if (tpe.symbol.hasFlag(Flags.JAVA) || (tpe.symbol.sourceFile eq null))
         <a class={tpe.toString().replace('.', '_')} href=""
           target={target}>{tpe.toString()}</a>
       /*
-      else if (tpe.symbol.sourceFile == null)
+      else if (tpe.symbol.sourceFile eq null)
         Text(tpe.toString())
       */
       else {
@@ -405,7 +405,7 @@ abstract class DocGenerator extends Models {
               else {
                 def aref1(sym: Symbol): NodeSeq = {
                   val isJava = sym hasFlag Flags.JAVA
-                  if (isJava || sym.sourceFile == null) {
+                  if (isJava || (sym.sourceFile eq null)) {
                     val name = sym.nameString
                     val args =
                       if (isJava) "()" // todo: arguments
@@ -1059,7 +1059,7 @@ abstract class DocGenerator extends Models {
 
   def organize0(mmbr: HasTree, map0: ListMap[Kind, TreeSet[HasTree]]) = {
     var map = map0
-    assert(mmbr.kind != null)
+    assert(mmbr.kind ne null)
     if (!map.contains(mmbr.kind))
       map = map.update(mmbr.kind, new TreeSet[HasTree])
     val sz = map(mmbr.kind).size
@@ -1083,7 +1083,7 @@ abstract class DocGenerator extends Models {
     import org.xml.sax.InputSource;
     val isrc1       = new InputSource(new StringReader(str));
     val parsedxml1  = XML.load(isrc1);
-    if (parsedxml1 == null) Text("BAD_COMMENT???");
+    if (parsedxml1 eq null) Text("BAD_COMMENT???");
     else parsedxml1;
     */
   }
@@ -1116,7 +1116,7 @@ abstract class DocGenerator extends Models {
 
   private def comment(comment: String, isShort: Boolean): NodeSeq = {
     var ret: List[Node] = Nil
-    assert(comment != null)
+    assert(comment ne null)
     // strip out any stars.
     var comment0 = comment.trim()
     assert(comment0 startsWith JDOC_START)
@@ -1139,7 +1139,7 @@ abstract class DocGenerator extends Models {
         if (mat2.matches) {
           attr = Triple(mat2.group(1), mat2.group(2), new StringBuilder(mat2.group(3)))
           attributes += attr
-        } else if (attr != null)
+        } else if (attr ne null)
           attr._3.append(s + LINE_SEPARATOR)
         else
           buf.append(s + LINE_SEPARATOR)
@@ -1163,7 +1163,7 @@ abstract class DocGenerator extends Models {
           {tag(attr._1)}
         </dt>
         <dd> {
-          if (attr._2 == null) NodeSeq.Empty
+          if (attr._2 eq null) NodeSeq.Empty
           else if (attr._1.equals("throws"))
             <code>{ exceptions.get(attr._2) match {
               case Some(p) =>
diff --git a/src/compiler/scala/tools/nsc/doc/DocUtil.scala b/src/compiler/scala/tools/nsc/doc/DocUtil.scala
index a2ec4c274b..92373c37fd 100644
--- a/src/compiler/scala/tools/nsc/doc/DocUtil.scala
+++ b/src/compiler/scala/tools/nsc/doc/DocUtil.scala
@@ -39,10 +39,10 @@ object DocUtil {
 
     def aref(href0: String, target: String, text: String): NodeSeq = {
       val href = Utility.escape(href0)
-      if (target != null && target.indexOf('<') != -1) throw new Error(target)
+      if ((target ne null) && target.indexOf('<') != -1) throw new Error(target)
 
       val t0 = Text(text)
-      if (target != null)
+      if ((target ne null))
         <a href={(relative + href)} target={(target)}>{t0}</a>;
       else
         <a href={(relative + href)}>{t0}</a>;
diff --git a/src/compiler/scala/tools/nsc/io/AbstractFile.scala b/src/compiler/scala/tools/nsc/io/AbstractFile.scala
index 9fe5ccfbd7..0ef0a18216 100644
--- a/src/compiler/scala/tools/nsc/io/AbstractFile.scala
+++ b/src/compiler/scala/tools/nsc/io/AbstractFile.scala
@@ -154,7 +154,7 @@ abstract class AbstractFile extends AnyRef with Iterable[AbstractFile] {
       assert(index < 0 || start < index)
       val name = path.substring(start, if (index < 0) length else index)
       file = file.lookupName(name, if (index < 0) directory else true)
-      if (file == null || index < 0) return file
+      if ((file eq null) || index < 0) return file
       start = index + 1
     }
     file
diff --git a/src/compiler/scala/tools/nsc/io/PlainFile.scala b/src/compiler/scala/tools/nsc/io/PlainFile.scala
index 1cf3241b80..c863a30e68 100644
--- a/src/compiler/scala/tools/nsc/io/PlainFile.scala
+++ b/src/compiler/scala/tools/nsc/io/PlainFile.scala
@@ -27,7 +27,7 @@ object PlainFile {
  */
 class PlainFile(val file: File) extends AbstractFile {
 
-  assert(file != null)
+  assert(file ne null)
   assert(file.exists(), "non-existent file: " + file)
 
   //########################################################################
@@ -67,7 +67,7 @@ class PlainFile(val file: File) extends AbstractFile {
   def elements: Iterator[AbstractFile] = {
     assert(isDirectory, "not a directory '" + this + "'")
     val names: Array[String] = file.list()
-    if (names == null || names.length == 0) Iterator.empty
+    if ((names eq null) || names.length == 0) Iterator.empty
     else Iterator.fromArray(names).map { name: String => new File(file, name) }
       .filter(.exists()).map(file => new PlainFile(file))
   }
diff --git a/src/compiler/scala/tools/nsc/io/VirtualFile.scala b/src/compiler/scala/tools/nsc/io/VirtualFile.scala
index 63e8674125..05c4dc8aec 100644
--- a/src/compiler/scala/tools/nsc/io/VirtualFile.scala
+++ b/src/compiler/scala/tools/nsc/io/VirtualFile.scala
@@ -17,7 +17,7 @@ import java.io.{File,InputStream}
  */
 class VirtualFile(val name: String, _path: String) extends AbstractFile {
 
-  assert(name != null && path != null, name + " - " + path)
+  assert((name ne null) && (path ne null), name + " - " + path)
 
   //########################################################################
   // Public Constructors
diff --git a/src/compiler/scala/tools/nsc/io/ZipArchive.scala b/src/compiler/scala/tools/nsc/io/ZipArchive.scala
index 177a13922c..4f2482c112 100644
--- a/src/compiler/scala/tools/nsc/io/ZipArchive.scala
+++ b/src/compiler/scala/tools/nsc/io/ZipArchive.scala
@@ -58,7 +58,7 @@ object ZipArchive {
  */
 final class ZipArchive(file: File, val archive: ZipFile) extends PlainFile(file) {
 
-  assert(archive != null)
+  assert(archive ne null)
   //########################################################################
   // Private Fields
 
@@ -73,7 +73,7 @@ final class ZipArchive(file: File, val archive: ZipFile) extends PlainFile(file)
 
   /** Returns all abstract subfiles of this abstract directory. */
   override def elements: Iterator[AbstractFile] = {
-    if (root == null) load()
+    if (root eq null) load()
     root.elements
   }
 
@@ -84,7 +84,7 @@ final class ZipArchive(file: File, val archive: ZipFile) extends PlainFile(file)
    * or a regular file.
    */
   override def lookupName(name: String, directory: Boolean): AbstractFile = {
-    if (root == null) load()
+    if (root eq null) load()
     root.lookupName(name, directory)
   }
 
@@ -105,7 +105,7 @@ final class ZipArchive(file: File, val archive: ZipFile) extends PlainFile(file)
              this.toString() + " - " + path);
       if (entry.isDirectory()) {
         val dir: DirEntry = getDir(dirs, path)
-        assert(dir.entry == null, this.toString() + " - " + path)
+        assert(dir.entry eq null, this.toString() + " - " + path)
         dir.entry = entry
       } else {
         val index = path.lastIndexOf('/')
@@ -165,7 +165,7 @@ final class ZipArchive(file: File, val archive: ZipFile) extends PlainFile(file)
     override def read = throw new Error("cannot read directories");
 
     override def lastModified: Long =
-      if (entry != null) entry.getTime() else super.lastModified
+      if (entry ne null) entry.getTime() else super.lastModified
 
     override def elements: Iterator[AbstractFile] = entries.values
 
diff --git a/src/compiler/scala/tools/nsc/matching/PatternMatchers.scala b/src/compiler/scala/tools/nsc/matching/PatternMatchers.scala
index 77f68e7153..da942995cb 100644
--- a/src/compiler/scala/tools/nsc/matching/PatternMatchers.scala
+++ b/src/compiler/scala/tools/nsc/matching/PatternMatchers.scala
@@ -391,13 +391,13 @@ trait PatternMatchers requires (transform.ExplicitOuter with PatternNodes) {
 
       case Bind(name, Ident(nme.WILDCARD)) => // x @ _
         val node = pDefaultPat(tree.pos, header.getTpe())
-        if ((env != null) && (tree.symbol != defs.PatternWildcard))
+        if ((env ne null) && (tree.symbol != defs.PatternWildcard))
           env.newBoundVar( tree.symbol, tree.tpe, header.selector);
         node
 
       case Bind(name, pat) =>                // x @ p
         val node = patternNode(pat, header, env)
-        if ((env != null) && (tree.symbol != defs.PatternWildcard)) {
+        if ((env ne null) && (tree.symbol != defs.PatternWildcard)) {
           val theValue = node.symbol match {
             case NoSymbol => header.selector
             case x        => Ident(x) setType x.tpe
@@ -426,7 +426,7 @@ trait PatternMatchers requires (transform.ExplicitOuter with PatternNodes) {
                   //Console.println(av.toString()+" IS  N O T  RIGHTIGNORING");
                   pSequencePat(tree.pos, tree.tpe, ts.length);
           }
-        } else if ((fn.symbol != null) &&
+        } else if ((fn.symbol ne null) &&
                    fn.symbol.isStable &&
                    !(fn.symbol.isModule &&
                      ((fn.symbol.flags & Flags.CASE) != 0))) {
@@ -527,7 +527,7 @@ trait PatternMatchers requires (transform.ExplicitOuter with PatternNodes) {
 */
       case _ =>
         Predef.error("unit = " + cunit + "; tree = " +
-          (if (tree == null) "null" else tree))
+          (if (tree eq null) "null" else tree))
     }
     //Console.print(t);
     t
@@ -609,7 +609,7 @@ print()
     var curHeader: Header = target.and match {
       case null => null
       case h: Header => h    // advance one step in intermediate representation
-      case b: Body if b.or != null => b.or.asInstanceOf[Header]
+      case b: Body if (b.or ne null) => b.or.asInstanceOf[Header]
       case b: Body =>
         if (b.guard(b.guard.length - 1) == EmptyTree) {
           cunit.error(pat.pos, "unreachable code")
@@ -620,7 +620,7 @@ print()
           null
         }
     }
-    if (curHeader == null) {                  // check if we have to add a new header
+    if (curHeader eq null) {                  // check if we have to add a new header
       //Console.println(" -- adding new header")
       //assert index >= 0 : casted;
       if (index < 0) { Predef.error("error entering:" + casted); return null }
@@ -630,7 +630,7 @@ print()
       curHeader  = newHeader(pat.pos, casted, index)
       target.and = curHeader; // (*)
 
-      if (bodycond != null) target.and = bodycond(target.and) // restores body with the guards
+      if (bodycond ne null) target.and = bodycond(target.and) // restores body with the guards
 
       curHeader.or = patternNode(pat, curHeader, env)
       enter(patArgs, curHeader.or, casted, env)
@@ -638,7 +638,7 @@ print()
     } else {
       //Console.println("   enter: using old header for casted = "+casted) // DBG
       // find most recent header
-      while (curHeader.next != null)
+      while (curHeader.next ne null)
         curHeader = curHeader.next
       // create node
       var patNode = patternNode(pat, curHeader, env)
@@ -655,7 +655,7 @@ print()
           }
           return enter(patArgs, next, casted, env);
         } else if (next.isDefaultPat() ||           // default case reached, or
-                   ((next.or == null) &&            //  no more alternatives and
+                   ((next.or eq null) &&            //  no more alternatives and
                     (patNode.isDefaultPat() || next.subsumes(patNode)))) {
                       // new node is default or subsumed
                       var header = pHeader(patNode.pos,
@@ -668,7 +668,7 @@ print()
                                    casted,
                                    env);
                     }
-          else if (next.or == null) {
+          else if (next.or eq null) {
             //Console.println(" -- add new branch!")
             return enter(patArgs, {next.or = patNode; patNode}, casted, env); // add new branch
           } else
@@ -757,9 +757,9 @@ print()
     protected def isSimpleSwitch(): Boolean  = {
       print();
       var patNode = root.and;
-      while (patNode != null) {
+      while (patNode ne null) {
         var node = patNode;
-        while (({node = node.or; node}) != null) {
+        while (({node = node.or; node}) ne null) {
           node match {
                 case VariablePat(tree) =>
                   //Konsole.println(((tree.symbol.flags & Flags.CASE) != 0));
@@ -770,7 +770,7 @@ print()
                       //outer: while (true) {
                       inner match {
                         case _h:Header =>
-                          if (_h.next != null)
+                          if (_h.next ne null)
                             throw Break(false);
                           funct(inner.or)
 
@@ -810,9 +810,9 @@ print()
   protected def isSimpleIntSwitch(): Boolean =
     if (isSameType(selector.tpe.widen, defs.IntClass.tpe)) {
       var patNode = root.and
-      while (patNode != null) {
+      while (patNode ne null) {
         var node = patNode;
-        while (({node = node.or; node}) != null) {
+        while (({node = node.or; node}) ne null) {
           node match {
             case ConstantPat(_) => ;
             case DefaultPat() => // experimental: enable simple int switch with default
@@ -847,7 +847,7 @@ print()
   protected def numCases(patNode1: PatternNode): Int = {
     var patNode = patNode1
     var n = 0
-    while (({patNode = patNode.or; patNode}) != null)
+    while (({patNode = patNode.or; patNode}) ne null)
     patNode match {
       case DefaultPat() => ;
       case _ => n = n + 1
@@ -857,9 +857,9 @@ print()
 
   protected def defaultBody(patNode1: PatternNode, otherwise: Tree ): Tree = {
     var patNode = patNode1;
-    while (patNode != null) {
+    while (patNode ne null) {
       var node = patNode
-      while (({node = node.or; node}) != null)
+      while (({node = node.or; node}) ne null)
       node match {
         case DefaultPat() =>
           return node.and.bodyToTree();
@@ -875,7 +875,7 @@ print()
    */
   def intSwitchToTree(): Tree = {
     def insert1(tag: Int, body: Tree, current: TagBodyPair): TagBodyPair = {
-      if (current == null)
+      if (current eq null)
         new TagBodyPair(tag, body, null)
       else if (tag > current.tag)
         new TagBodyPair(current.tag, current.body, insert1(tag, body, current.next))
@@ -911,9 +911,9 @@ print()
     var mappings: TagBodyPair = null
     var defaultBody1: Tree = matchError
     var patNode = root.and
-    while (patNode != null) {
+    while (patNode ne null) {
       var node = patNode.or
-      while (node != null) {
+      while (node ne null) {
         node match {
           case DefaultPat() =>
             //experimental: allow default body
@@ -935,7 +935,7 @@ print()
 
     var n = mappings.length()
     var nCases: List[CaseDef] = Nil
-    while (mappings != null) {
+    while (mappings ne null) {
       nCases = CaseDef(Literal(mappings.tag),
                        mappings.body) :: nCases;
       mappings = mappings.next;
@@ -944,7 +944,7 @@ print()
     val tags = new Array[Int](n);
     val bodies = new Array[Tree](n);
     n = 0;
-    while (mappings != null) {
+    while (mappings ne null) {
       tags(n) = mappings.tag;
       bodies(n) = mappings.body;
       n = n + 1;
@@ -977,7 +977,7 @@ print()
       if (!optimize || !isSubType(selType, defs.ScalaObjectClass.tpe))
         return false;
       var cases = 0;
-      while (alts != null) {
+      while (alts ne null) {
         alts match {
           case ConstrPat(_) =>
             if (alts.getTpe().symbol.hasFlag(Flags.CASE))
@@ -998,7 +998,7 @@ print()
     var node = node1;
 
     var res: Tree = typed(Literal(Constant(false))); //.setInfo(defs.BooleanClass);
-    while (node != null)
+    while (node ne null)
     node match {
 
       case _h:Header =>
@@ -1039,7 +1039,7 @@ print()
           res = Or(squeezedBlock(ts.toList, res0), res);
           i = i - 1
         }
-      if (_b.or != null)
+      if (_b.or ne null)
         res = Or(res, toTree(_b.or))
       return res;
         case _ =>
@@ -1059,7 +1059,7 @@ print()
 
     protected def toOptTree(node1: PatternNode, selector: Tree): Tree = {
       def insert2(tag: Int, node: PatternNode, current: TagNodePair): TagNodePair = {
-        if (current == null)
+        if (current eq null)
           return new TagNodePair(tag, node, null);
         else if (tag > current.tag)
           return new TagNodePair(current.tag, current.node, insert2(tag, node, current.next));
@@ -1080,7 +1080,7 @@ print()
       //System.err.println("pm.toOptTree called"+node);
       var cases: TagNodePair  = null
       var defaultCase: PatternNode  = null
-      while (node != null)
+      while (node ne null)
       node match {
         case ConstrPat(casted) =>
           cases = insertNode(node.getTpe().symbol.tag, node, cases)
@@ -1115,18 +1115,18 @@ print()
           List()),
         tags,
         bodies,
-        { if (defaultCase == null) Literal(false) else toTree(defaultCase.and) },
+        { if (defaultCase eq null) Literal(false) else toTree(defaultCase.and) },
                         defs.boolean_TYPE());
                         */
       var nCases: List[CaseDef] = Nil
-      while (cases != null) {
+      while (cases ne null) {
         nCases = CaseDef(Literal(Constant(cases.tag)),
                          toTree(cases.node, selector)) :: nCases;
         cases = cases.next
       }
 
       val defBody =
-        if (defaultCase == null) Literal(Constant(false))
+        if (defaultCase eq null) Literal(Constant(false))
         else toTree(defaultCase.and)
 
       nCases = CaseDef(Ident(nme.WILDCARD), defBody) :: nCases;
@@ -1149,9 +1149,9 @@ print()
 
     protected def toTree(node: PatternNode, selector:Tree): Tree = {
       //Konsole.println("pm.toTree("+node+","+selector+") selector.tpe = "+selector.tpe+")")
-      if (selector.tpe == null)
+      if (selector.tpe eq null)
         scala.Predef.error("cannot go on")
-      if (node == null)
+      if (node eq null)
         return Literal(Constant(false));
       else
         node match {
@@ -1248,7 +1248,7 @@ print()
               else And(tpetest, seqLongerThan(treeAsSeq, ntpe, minlen))
 
             var bindings =
-              if(castedRest != null)
+              if(castedRest ne null)
                 List(ValDef(castedRest, seqDrop(treeAsSeq.duplicate, minlen)))
               else
                 List()
diff --git a/src/compiler/scala/tools/nsc/matching/PatternNodes.scala b/src/compiler/scala/tools/nsc/matching/PatternNodes.scala
index eda7336711..b6806c18d5 100644
--- a/src/compiler/scala/tools/nsc/matching/PatternNodes.scala
+++ b/src/compiler/scala/tools/nsc/matching/PatternNodes.scala
@@ -138,7 +138,7 @@ trait PatternNodes requires transform.ExplicitOuter {
       case VariablePat(tree) =>
         q match {
           case VariablePat(other) =>
-            (tree.symbol != null) &&
+            (tree.symbol ne null) &&
             (tree.symbol != NoSymbol) &&
             (!tree.symbol.isError) &&
             (tree.symbol == other.symbol)
@@ -175,7 +175,7 @@ trait PatternNodes requires transform.ExplicitOuter {
     def print(indent: String, sb: StringBuilder): StringBuilder = {
       val patNode = this
 
-      def cont = if (patNode.or != null) patNode.or.print(indent, sb) else sb
+      def cont = if (patNode.or ne null) patNode.or.print(indent, sb) else sb
 
       def newIndent(s: String) = {
         val removeBar: Boolean = (null == patNode.or)
@@ -190,7 +190,7 @@ trait PatternNodes requires transform.ExplicitOuter {
         sb.toString()
       }
 
-      if (patNode == null)
+      if (patNode eq null)
         sb.append(indent).append("NULL")
       else
         patNode match {
@@ -202,7 +202,7 @@ trait PatternNodes requires transform.ExplicitOuter {
           sb.append(indent + "HEADER(" + patNode.getTpe() +
                           ", " + selector + ")").append('\n')
           patNode.or.print(indent + "|", sb)
-          if (next != null)
+          if (next ne null)
             next.print(indent, sb)
           else
             sb
diff --git a/src/compiler/scala/tools/nsc/matching/TransMatcher.scala b/src/compiler/scala/tools/nsc/matching/TransMatcher.scala
index 1ab16f0203..cdd4c5fee2 100644
--- a/src/compiler/scala/tools/nsc/matching/TransMatcher.scala
+++ b/src/compiler/scala/tools/nsc/matching/TransMatcher.scala
@@ -47,7 +47,7 @@ with PatternMatchers */ {
       (treeInfo.isVariableName(name)) && (name != nme.USCOREkw)
 
     def isVariableSymbol(sym: Symbol): Boolean =
-      (sym != null) && (!sym.isPrimaryConstructor)
+      (sym ne null) && (!sym.isPrimaryConstructor)
 
     def traverse(tree: Tree): Unit = {
       tree match {
diff --git a/src/compiler/scala/tools/nsc/models/Models.scala b/src/compiler/scala/tools/nsc/models/Models.scala
index 07286a0153..db000efd1e 100644
--- a/src/compiler/scala/tools/nsc/models/Models.scala
+++ b/src/compiler/scala/tools/nsc/models/Models.scala
@@ -126,8 +126,8 @@ abstract class Models {
         }
         ret = ret + " : " + textFor(vdef.tpt)
       case atd: AbsTypeDef =>
-        ret = ret + ((if(atd.hi != null) " <: " + textFor(atd.hi) else "") +
-                     (if(atd.lo != null) " >: " + textFor(atd.lo) else ""));
+        ret = ret + ((if(atd.hi ne null) " <: " + textFor(atd.hi) else "") +
+                     (if(atd.lo ne null) " >: " + textFor(atd.lo) else ""));
       case _ =>
         ret = ret + tree.toString()
     }
@@ -210,7 +210,7 @@ abstract class Models {
         Console.err.println("PACKAGE: " + mmbr1.symbol + " " + members1.length)
       } else if (isMember(mmbr1)) {
         val mmbr2 = member(mmbr1, members1)
-        if (mmbr2 != null) {
+        if (mmbr2 ne null) {
           var found = false
           for (val mmbr <- members) if (!found && mmbr.replacedBy(mmbr2)) {
             //Console.err.println("REPLACE: " + mmbr + " with " + mmbr2)
@@ -252,7 +252,7 @@ abstract class Models {
       } else false
 
     override def update(tree0: Tree): Boolean = {
-      val updated = tree == null || (treex.mods != tree0.asInstanceOf[MemberDef].mods)
+      val updated = (tree eq null) || (treex.mods != tree0.asInstanceOf[MemberDef].mods)
       super.update(tree0) || updated;
     }
   }
@@ -271,7 +271,7 @@ abstract class Models {
 
     override def update(tree0: Tree): Boolean = {
       val tree1 = tree0.asInstanceOf[ValOrDefDef]
-      val updated = tree == null || treex.tpe != tree1.tpe
+      val updated = (tree eq null) || treex.tpe != tree1.tpe
       update0(flatten(tree1.rhs, (tree2: Tree) => isMember(tree2)))
       super.update(tree0) || updated
     }
@@ -313,7 +313,7 @@ abstract class Models {
       val tree0 = if (tree.isInstanceOf[DefDef]) {
         val ddef = tree.asInstanceOf[DefDef]
         ddef.mods
-        if (ddef.mods.isAccessor && ddef.symbol != null) {
+        if (ddef.mods.isAccessor && (ddef.symbol ne null)) {
           val sym0 = ddef.symbol;
           if (sym0.isSetter) return null;
           assert(sym0.isGetter);
@@ -336,7 +336,7 @@ abstract class Models {
       } else super.member(tree, members)
 
       def sym = tree0.symbol
-      if (tree0 == null || tree0.pos == NoPos) null
+      if ((tree0 eq null) || tree0.pos == NoPos) null
       else if (!acceptPrivate &&
                tree0.isInstanceOf[ValOrDefDef] &&
                tree.asInstanceOf[ValOrDefDef].mods.isPrivate) null
diff --git a/src/compiler/scala/tools/nsc/models/SemanticTokens.scala b/src/compiler/scala/tools/nsc/models/SemanticTokens.scala
index 6404a4fa28..3d4b199304 100644
--- a/src/compiler/scala/tools/nsc/models/SemanticTokens.scala
+++ b/src/compiler/scala/tools/nsc/models/SemanticTokens.scala
@@ -131,10 +131,10 @@ class SemanticTokens(val compiler: Global) {
     def source = unit.source
 
     def dbg(tree : Tree) = {
-      def treePos : Int = if (tree != null) tree.pos else -1;
+      def treePos : Int = if (tree ne null) tree.pos else -1;
       (
         "TREE=" + tree +
-          (if (tree != null) (" CLASS=" + tree.getClass()) else "") +
+          (if (tree ne null) (" CLASS=" + tree.getClass()) else "") +
             " SYM=" + tree.symbol +
               " POS=" +
                 (new Position(source, treePos)).dbgString
@@ -188,7 +188,7 @@ class SemanticTokens(val compiler: Global) {
     class Use(symbol0: Symbol, tpe0: Type) extends Semantic(symbol0) {
       info.uses += this
 
-      override def tpe : Type = if (tpe0 != null) tpe0 else super.tpe;
+      override def tpe : Type = if (tpe0 ne null) tpe0 else super.tpe;
       override def toString() = "use-" + name + "-" + symbol.getClass();
     }
     val list = new TokenList
@@ -244,7 +244,7 @@ class SemanticTokens(val compiler: Global) {
               }
               try {
           //TPT=scala.Iterator[DocGenerator.this.compiler0.CompilationUnit] 260 class scala.tools.nsc.ast.Trees$TypeTree scala.Iterator[DocGenerator.this.compiler0.CompilationUnit] class scala.tools.nsc.symtab.Types$$anon$5
-          if (tree.tpt == null || tree.tpt.tpe == null) {
+          if ((tree.tpt eq null) || (tree.tpt.tpe eq null)) {
             //Console.err.println("BAD: " + tree.tpt + " in " + tree);
           } else {
             //Console.err.println("TPT=" + tree.tpt + " " + tree.tpt.pos + " " + tree.tpt.getClass() + " " + tree.tpt.tpe + " " + tree.tpt.tpe.getClass() + " " + tree.tpt.tpe.getClass().getSuperclass());
@@ -283,14 +283,14 @@ class SemanticTokens(val compiler: Global) {
         build(tree.body)
       case tree : TypeTree =>
         val treex = tree
-        val tree1 = if (tree.original != null) tree.original else tree
+        val tree1 = if (tree.original ne null) tree.original else tree
         def classes(clazz: java.lang.Class): List[java.lang.Class] =
-          if (clazz == null) Nil
+          if (clazz eq null) Nil
           else clazz :: classes(clazz.getSuperclass())
-        if (tree.original == null) {
+        if (tree.original eq null) {
           if (false) Console.err.println("NO_ORIGINAL: " + tree + " " + tree.tpe + " " + classes(tree.tpe.getClass()));
         }
-        if (tree.tpe != null) buildT(tree1, tree.tpe);
+        if (tree.tpe ne null) buildT(tree1, tree.tpe);
         def buildT( tree : Tree, tpe : Type) : Unit = if (tree.pos != NoPos) tpe match {
           case tpe0 : TypeRef => tree match {
             case apt : AppliedTypeTree =>
@@ -315,10 +315,10 @@ class SemanticTokens(val compiler: Global) {
                           throw e;
               }
             case tpt : TypeTree =>
-          if (tpt.symbol != null) {
+          if (tpt.symbol ne null) {
             Console.err.println("SYM0 " + tpt.symbol + " " + unit.source.dbg(tpt.pos));
             buildUse(tpt.symbol, tpt.pos, tpe0);
-          } else if (tpe0.symbol != null) {
+          } else if (tpe0.symbol ne null) {
             //Console.err.println("TYPE_SYM1 " + tpe0.symbol + " " + unit.source.dbg(tpt.pos));
             buildUse(tpe0.symbol, tpt.pos, tpe0);
           } else {
@@ -334,7 +334,7 @@ class SemanticTokens(val compiler: Global) {
           }
           case tpe0 : MethodType => tree match {
             case tpt: TypeTree =>
-              if (tpt.original != null) buildT(tpt.original, tpe);
+              if (tpt.original ne null) buildT(tpt.original, tpe);
               else {
                         Console.err.println("UNKNOWN TPT3: " + tree + " vs. " + tpe0 + " " + unit.source.content(tree.pos));
               }
@@ -389,7 +389,7 @@ class SemanticTokens(val compiler: Global) {
         } else if (trees.isEmpty != types.isEmpty) {
              if (false && doLog) {
         Console.println("" + treex + " vs. " + treex.original);
-        if (treex.original != null)
+        if (treex.original ne null)
           Console.println("" + treex.tpe + " vs. " + treex.original.tpe);
                logError("Tree vs. Type mismatch: " + trees + " " + types + " " + unit.source.dbg(tree.pos), null);
         doLog = false;
@@ -468,7 +468,7 @@ class SemanticTokens(val compiler: Global) {
       case tree : Alternative => build(tree.trees);
       case tree : This    =>
         //Console.err.println("THIS: " + tree.symbol + " " + tree.qual + " " + unit.source.dbg(tree.pos) + " " + tree.tpe);
-        if (tree.symbol != null) buildUse(tree.symbol, tree.pos, tree.tpe);
+        if (tree.symbol ne null) buildUse(tree.symbol, tree.pos, tree.tpe);
         //Thread.dumpStack();
       case tree : AliasTypeDef =>
         //Console.err.println("ALIAS: " + tree);
diff --git a/src/compiler/scala/tools/nsc/reporters/AbstractReporter.scala b/src/compiler/scala/tools/nsc/reporters/AbstractReporter.scala
index c2953e0a5c..b899c04999 100644
--- a/src/compiler/scala/tools/nsc/reporters/AbstractReporter.scala
+++ b/src/compiler/scala/tools/nsc/reporters/AbstractReporter.scala
@@ -44,7 +44,7 @@ abstract class AbstractReporter extends Reporter {
 
   /** Logs a position and returns true if it was already logged. */
   private def testAndLog(pos : Position) : Boolean = {
-    if (pos == null) return false;
+    if (pos eq null) return false;
     if (pos.column == 0) return false;
     if (positions.contains(pos)) return true;
     positions += (pos);
diff --git a/src/compiler/scala/tools/nsc/reporters/ConsoleReporter.scala b/src/compiler/scala/tools/nsc/reporters/ConsoleReporter.scala
index 8c59c21f19..f020e0c6af 100644
--- a/src/compiler/scala/tools/nsc/reporters/ConsoleReporter.scala
+++ b/src/compiler/scala/tools/nsc/reporters/ConsoleReporter.scala
@@ -34,7 +34,7 @@ class ConsoleReporter(reader : BufferedReader, writer : PrintWriter) extends Abs
   }
   def clabel(severity : Severity) = {
     val label0 = label(severity)
-    if (label0 == null) "" else label0 + ": "
+    if (label0 eq null) "" else label0 + ": "
   }
 
 
@@ -69,7 +69,7 @@ class ConsoleReporter(reader : BufferedReader, writer : PrintWriter) extends Abs
 
   /** Prints the message with the given position indication. */
   def printMessage(posIn : Position, msg : String) : Unit = {
-    if (posIn != null) {
+    if (posIn ne null) {
       val pos = posIn.inUltimateSource
       val buf = new StringBuilder(msg)
       buf.insert(0, " ")
@@ -89,12 +89,12 @@ class ConsoleReporter(reader : BufferedReader, writer : PrintWriter) extends Abs
 
   def print(pos : Position, msg : String, severity : Severity) = printMessage(pos, clabel(severity) + msg)
 
-  def printSourceLine(pos : Position) = if (pos != null && pos.offset != Position.NOPOS) {
+  def printSourceLine(pos : Position) = if ((pos ne null) && pos.offset != Position.NOPOS) {
     printMessage(pos.lineContent.stripLineEnd)
     printColumnMarker(pos)
   }
   /** Prints the column marker of the given position. */
-  def printColumnMarker(pos : Position) = if (pos != null) {
+  def printColumnMarker(pos : Position) = if (pos ne null) {
     val buffer = new StringBuilder(pos.column)
     var i = 1
     while (i < pos.column) {
@@ -123,7 +123,7 @@ class ConsoleReporter(reader : BufferedReader, writer : PrintWriter) extends Abs
       writer.print("r)esume, a)bort: ")
       writer.flush()
       var line = reader.readLine()
-      if (line != null) {
+      if (line ne null) {
 	line = line.toLowerCase()
 	if ("abort".startsWith(line))
             throw new Error("user abort")
diff --git a/src/compiler/scala/tools/nsc/symtab/Definitions.scala b/src/compiler/scala/tools/nsc/symtab/Definitions.scala
index 7aa716dde3..59bf1e71a0 100644
--- a/src/compiler/scala/tools/nsc/symtab/Definitions.scala
+++ b/src/compiler/scala/tools/nsc/symtab/Definitions.scala
@@ -397,7 +397,7 @@ trait Definitions requires SymbolTable {
       newMethod(BooleanClass, nme.XOR,  boolparam, booltype)
 
       def initValueClass(clazz: Symbol, isCardinal: Boolean): Unit = {
-        assert (clazz != null)
+        assert (clazz ne null)
 
         def addBinops(params: List[Type], restype: Type, isCardinal: Boolean) = {
           newMethod(clazz, nme.EQ,  params, booltype)
@@ -535,7 +535,7 @@ trait Definitions requires SymbolTable {
 
       JavaLangPackage = getModule("java.lang")
       ScalaPackage = getModule("scala")
-      assert(ScalaPackage != null, "Scala package is null")
+      assert(ScalaPackage ne null, "Scala package is null")
       ScalaPackageClass = ScalaPackage.tpe.symbol
 
       AnyClass = newClass(ScalaPackageClass, nme.Any, List()).setFlag(ABSTRACT)
diff --git a/src/compiler/scala/tools/nsc/symtab/Names.scala b/src/compiler/scala/tools/nsc/symtab/Names.scala
index dc73601a48..a27a2e5197 100644
--- a/src/compiler/scala/tools/nsc/symtab/Names.scala
+++ b/src/compiler/scala/tools/nsc/symtab/Names.scala
@@ -90,9 +90,9 @@ class Names {
   def newTermName(cs: Array[char], offset: int, len: int): Name = {
     val h = hashValue(cs, offset, len) & HASH_MASK;
     var n = termHashtable(h);
-    while ((n != null) && (n.length != len || !equals(n.start, cs, offset, len)))
+    while ((n ne null) && (n.length != len || !equals(n.start, cs, offset, len)))
       n = n.next;
-    if (n == null) {
+    if (n eq null) {
       n = new TermName(nc, len, h)
       enterChars(cs, offset, len)
     }
@@ -370,9 +370,9 @@ class Names {
     def toTypeName = {
       val h = hashValue(chrs, index, len) & HASH_MASK
       var n = typeHashtable(h)
-      while (n != null && n.start != index)
+      while ((n ne null) && n.start != index)
         n = n.next;
-      if (n == null)
+      if (n eq null)
         n = new TypeName(index, len, h);
       n
     }
@@ -388,9 +388,9 @@ class Names {
     def toTermName: Name = {
       val h = hashValue(chrs, index, len) & HASH_MASK
       var n = termHashtable(h)
-      while (n != null && n.start != index)
+      while ((n ne null) && n.start != index)
         n = n.next;
-      if (n == null)
+      if (n eq null)
         n = new TermName(index, len, h);
       n
     }
diff --git a/src/compiler/scala/tools/nsc/symtab/Scopes.scala b/src/compiler/scala/tools/nsc/symtab/Scopes.scala
index 3c2a1e8724..cfaccf44f1 100644
--- a/src/compiler/scala/tools/nsc/symtab/Scopes.scala
+++ b/src/compiler/scala/tools/nsc/symtab/Scopes.scala
@@ -92,7 +92,7 @@ trait Scopes requires SymbolTable {
     def this(base: Scope) = {
       this(base.elems)
 /*
-      if (base.hashtable != null) {
+      if (base.hashtable ne null) {
         this.hashtable = new Array[ScopeEntry](HASHSIZE)
         System.arraycopy(base.hashtable, 0, this.hashtable, 0, HASHSIZE)
       }
@@ -113,13 +113,13 @@ trait Scopes requires SymbolTable {
     }
 
     /** is the scope empty? */
-    def isEmpty: boolean = elems == null
+    def isEmpty: boolean = elems eq null
 
     /** the number of entries in this scope */
     def size: int = {
       var s = 0
       var e = elems
-      while (e != null) {
+      while (e ne null) {
         s = s + 1
         e = e.next
       }
@@ -132,7 +132,7 @@ trait Scopes requires SymbolTable {
      */
     def enter(e: ScopeEntry): unit = {
       elemsCache = null
-      if (hashtable != null) {
+      if (hashtable ne null) {
         val i = e.sym.name.start & HASHMASK
         elems.tail = hashtable(i)
         hashtable(i) = elems
@@ -162,7 +162,7 @@ trait Scopes requires SymbolTable {
     }
 
     private def enterInHash(e: ScopeEntry): unit =
-      if (e != null) {
+      if (e ne null) {
         enterInHash(e.next)
         val i = e.sym.name.start & HASHMASK
         e.tail = hashtable(i)
@@ -181,7 +181,7 @@ trait Scopes requires SymbolTable {
         while (e1.next != e) e1 = e1.next;
         e1.next = e.next
       }
-      if (hashtable != null) {
+      if (hashtable ne null) {
         var e1 = hashtable(e.sym.name.start & HASHMASK)
         if (e1 == e) {
           hashtable(e.sym.name.start & HASHMASK) = e.tail
@@ -196,7 +196,7 @@ trait Scopes requires SymbolTable {
     /** remove symbol */
     def unlink(sym: Symbol): unit = {
       var e = lookupEntry(sym.name)
-      while (e != null) {
+      while (e ne null) {
         if (e.sym == sym) unlink(e);
         e = lookupNextEntry(e)
       }
@@ -209,7 +209,7 @@ trait Scopes requires SymbolTable {
      */
     def lookup(name: Name): Symbol = {
       val e = lookupEntry(name)
-      if (e == null) NoSymbol else e.sym
+      if (e eq null) NoSymbol else e.sym
     }
 
     /** lookup a symbol entry matching given name.
@@ -219,12 +219,12 @@ trait Scopes requires SymbolTable {
      */
     def lookupEntry(name: Name): ScopeEntry = {
       var e: ScopeEntry = null
-      if (false & hashtable != null) {
+      if (false & (hashtable ne null)) {
         e = hashtable(name.start & HASHMASK)
-        while (e != null && e.sym.name != name) e = e.tail;
+        while ((e ne null) && e.sym.name != name) e = e.tail;
       } else {
         e = elems
-        while (e != null && e.sym.name != name) {
+        while ((e ne null) && e.sym.name != name) {
           e = e.next;
         }
       }
@@ -234,20 +234,20 @@ trait Scopes requires SymbolTable {
     /** lookup next entry with same name as this one */
     def lookupNextEntry(entry: ScopeEntry): ScopeEntry = {
       var e = entry
-      if (hashtable != null) //debug
-      do { e = e.tail } while (e != null && e.sym.name != entry.sym.name)
+      if (hashtable ne null) //debug
+      do { e = e.tail } while ((e ne null) && e.sym.name != entry.sym.name)
       else
-        do { e = e.next } while (e != null && e.sym.name != entry.sym.name);
+        do { e = e.next } while ((e ne null) && e.sym.name != entry.sym.name);
       e
     }
 
     /** Return all symbols as a list in the order they were entered in this scope.
      */
     def toList: List[Symbol] = {
-      if (elemsCache == null) {
+      if (elemsCache eq null) {
         elemsCache = Nil
         var e = elems
-        while (e != null && e.owner == this) {
+        while ((e ne null) && e.owner == this) {
           elemsCache = e.sym :: elemsCache
           e = e.next
         }
diff --git a/src/compiler/scala/tools/nsc/symtab/SymbolLoaders.scala b/src/compiler/scala/tools/nsc/symtab/SymbolLoaders.scala
index be4c397d7d..3df8884e50 100644
--- a/src/compiler/scala/tools/nsc/symtab/SymbolLoaders.scala
+++ b/src/compiler/scala/tools/nsc/symtab/SymbolLoaders.scala
@@ -42,8 +42,8 @@ abstract class SymbolLoaders {
     private var ok = false
 /*
     private def setSource(sym: Symbol, sourceFile0: AbstractFile): unit = sym match {
-      case clazz: ClassSymbol => if (sourceFile0 != null) clazz.sourceFile = sourceFile0;
-      case _ => if (sourceFile0 != null) if (false) System.err.println("YYY: " + sym + " " + sourceFile0);
+      case clazz: ClassSymbol => if (sourceFile0 ne null) clazz.sourceFile = sourceFile0;
+      case _ => if (sourceFile0 ne null) if (false) System.err.println("YYY: " + sym + " " + sourceFile0);
     }
 */
     def sourceFile : AbstractFile = null
@@ -66,7 +66,7 @@ abstract class SymbolLoaders {
           if (settings.debug.value) ex.printStackTrace();
           val msg = ex.getMessage()
           error(
-            if (msg == null) "i/o error while loading " + root.name
+            if (msg eq null) "i/o error while loading " + root.name
             else "error while loading " + root.name + ", " + msg);
       }
       initRoot(root)
@@ -120,7 +120,7 @@ abstract class SymbolLoaders {
         owner.info.decls.enter(clazz)
         owner.info.decls.enter(module)
 /*
-        if (completer.sourceFile != null) {
+        if (completer.sourceFile ne null) {
           clazz.sourceFile = completer.sourceFile;
           module.moduleClass.sourceFile = completer.sourceFile
         }
@@ -131,7 +131,7 @@ abstract class SymbolLoaders {
 
       val classes  = new HashMap[String, global.classPath0.Context]
       val packages = new HashMap[String, global.classPath0.Context]
-      for (val dir <- directory.entries) if (dir.location != null) {
+      for (val dir <- directory.entries) if (dir.location ne null) {
         for (val file <- dir.location) {
           if (file.isDirectory && directory.validPackage(file.name) && !packages.isDefinedAt(file.name))
             packages(file.name) = directory.find(file.name, true);
@@ -139,12 +139,12 @@ abstract class SymbolLoaders {
             val name = file.name.substring(0, file.name.length() - (".class").length());
             if (isValid(name) && !classes.isDefinedAt(name)) {
               val clazz = directory.find(name, false)
-              if (clazz != null) classes(name) = clazz
+              if (clazz ne null) classes(name) = clazz
             }
           }
         }
       }
-      for (val dir <- directory.entries) if (dir.source != null) {
+      for (val dir <- directory.entries) if (dir.source ne null) {
         for (val file <- dir.source.location) {
           if (file.isDirectory && directory.validPackage(file.name) && !packages.isDefinedAt(file.name))
             packages(file.name) = directory.find(file.name, true);
@@ -152,7 +152,7 @@ abstract class SymbolLoaders {
             val name = file.name.substring(0, file.name.length() - (".scala").length());
             if (isValid(name) && !classes.isDefinedAt(name)) {
               val source = directory.find(name, false)
-              if (source != null) classes(name) = source
+              if (source ne null) classes(name) = source
             }
           }
         }
@@ -165,7 +165,7 @@ abstract class SymbolLoaders {
         val loader = if (!file.isSourceFile) {
           new ClassfileLoader(file.classFile, file.sourceFile, file.sourcePath);
         } else {
-          assert(file.sourceFile != null)
+          assert(file.sourceFile ne null)
           new SourcefileLoader(file.sourceFile)
         }
         enterClassAndModule(name, loader)
@@ -189,7 +189,7 @@ abstract class SymbolLoaders {
     }
     protected def doComplete(root: Symbol): unit = {
       classfileParser.parse(classFile, root)
-      if (sourceFile != null) root match {
+      if (sourceFile ne null) root match {
         case clazz : ClassSymbol => clazz.sourceFile = sourceFile
         case _ =>
       }
diff --git a/src/compiler/scala/tools/nsc/symtab/SymbolTable.scala b/src/compiler/scala/tools/nsc/symtab/SymbolTable.scala
index ccc33587dd..b1f7a817fd 100644
--- a/src/compiler/scala/tools/nsc/symtab/SymbolTable.scala
+++ b/src/compiler/scala/tools/nsc/symtab/SymbolTable.scala
@@ -41,7 +41,7 @@ abstract class SymbolTable extends Names
 
   def phase_=(p: Phase): unit = {
     //System.out.println("setting phase to " + p)
-    assert(p != null && p != NoPhase)
+    assert((p ne null) && p != NoPhase)
     ph = p
     per = (currentRunId << 8) + p.id
   }
diff --git a/src/compiler/scala/tools/nsc/symtab/Symbols.scala b/src/compiler/scala/tools/nsc/symtab/Symbols.scala
index cd8d3c2ea2..952ba7e582 100644
--- a/src/compiler/scala/tools/nsc/symtab/Symbols.scala
+++ b/src/compiler/scala/tools/nsc/symtab/Symbols.scala
@@ -378,8 +378,8 @@ trait Symbols requires SymbolTable {
       while (runId(validTo) != currentRunId) {
         //if (settings.debug.value) System.out.println("completing " + this);//DEBUG
         var ifs = infos
-        assert(ifs != null, this.name)
-        while (ifs.prev != null) {
+        assert(ifs ne null, this.name)
+        while (ifs.prev ne null) {
           ifs = ifs.prev
         }
         val tp = ifs.info
@@ -408,7 +408,7 @@ trait Symbols requires SymbolTable {
 
     /** Set initial info. */
     def setInfo(info: Type): this.type = {
-      assert(info != null)
+      assert(info ne null)
       var period = currentPeriod
       if (phaseId(period) == 0) {
         // can happen when we initialize NoSymbol before running the compiler
@@ -458,11 +458,11 @@ trait Symbols requires SymbolTable {
             phase = current
             validTo = currentPeriod
           }
-          assert(infos != null, name)
+          assert(infos ne null, name)
           infos.info
       } else {
         var infos = this.infos
-        while (phase.id < infos.start && infos.prev != null) infos = infos.prev
+        while (phase.id < infos.start && (infos.prev ne null)) infos = infos.prev
         infos.info
       }
     }
@@ -476,8 +476,8 @@ trait Symbols requires SymbolTable {
     /** Was symbol's type updated during given phase? */
     final def isUpdatedAt(pid: Phase#Id): boolean = {
       var infos = this.infos
-      while (infos != null && infos.start != pid + 1) infos = infos.prev
-      infos != null
+      while ((infos ne null) && infos.start != pid + 1) infos = infos.prev
+      (infos ne null)
     }
 
     /** The type constructor of a symbol is:
@@ -1082,16 +1082,16 @@ trait Symbols requires SymbolTable {
           tpeCache = typeRef(if (isTypeParameterOrSkolem) NoPrefix else owner.thisType, this, targs)
         }
       }
-      assert(tpeCache != null/*, "" + this + " " + phase*/)//debug
+      assert(tpeCache ne null/*, "" + this + " " + phase*/)//debug
       tpeCache
     }
 
     override def typeConstructor: Type = {
-      if (tyconCache == null || tyconRunId != currentRunId) {
+      if ((tyconCache eq null) || tyconRunId != currentRunId) {
         tyconCache = typeRef(if (isTypeParameter) NoPrefix else owner.thisType, this, List())
         tyconRunId = currentRunId
       }
-      assert(tyconCache != null)
+      assert(tyconCache ne null)
       tyconCache
     }
 
@@ -1148,7 +1148,7 @@ trait Symbols requires SymbolTable {
       source = f
     }
     override def isFromClassFile = {
-      if (classFile != null) true
+      if (classFile ne null) true
       else if (owner.isPackageClass) false
       else super.isFromClassFile
     }
@@ -1264,7 +1264,7 @@ trait Symbols requires SymbolTable {
 
   /** A class for type histories */
   private case class TypeHistory(start: Phase#Id, info: Type, prev: TypeHistory) {
-    assert(prev == null || start > prev.start, this)
+    assert((prev eq null) || start > prev.start, this)
     assert(start != 0)
     override def toString() =
       "TypeHistory(" + phaseWithId(start) + "," + info + "," + prev + ")"
diff --git a/src/compiler/scala/tools/nsc/symtab/Types.scala b/src/compiler/scala/tools/nsc/symtab/Types.scala
index 091d7117ef..6ecf89ad04 100644
--- a/src/compiler/scala/tools/nsc/symtab/Types.scala
+++ b/src/compiler/scala/tools/nsc/symtab/Types.scala
@@ -386,7 +386,7 @@ trait Types requires SymbolTable {
       var alts: List[Symbol] = List()
       var sym: Symbol = NoSymbol
       var e: ScopeEntry = decls.lookupEntry(name)
-      while (e != null) {
+      while (e ne null) {
         if (!e.sym.hasFlag(excludedFlags)) {
           if (sym == NoSymbol) sym = e.sym
           else {
@@ -428,7 +428,7 @@ trait Types requires SymbolTable {
           bcs = if (name == nme.CONSTRUCTOR) Nil else bcs.tail
           var entry =
             if (name == nme.ANYNAME) decls.elems else decls lookupEntry name
-          while (entry != null) {
+          while (entry ne null) {
             val sym = entry.sym
             if (sym.getFlag(requiredFlags) == requiredFlags) {
               val excl = sym.getFlag(excluded)
@@ -440,28 +440,28 @@ trait Types requires SymbolTable {
                   return sym
                 } else if (member == NoSymbol) {
                   member = sym
-                } else if (members == null) {
+                } else if (members eq null) {
                   if (member.name != sym.name ||
                       !(member == sym ||
                         member.owner != sym.owner &&
                         !sym.hasFlag(PRIVATE) && {
-                          if (self == null) self = this.narrow;
+                          if (self eq null) self = this.narrow;
                           (self.memberType(member) matches self.memberType(sym))
                         })) {
                     members = newScope(List(member, sym))
                   }
                 } else {
                   var prevEntry = members lookupEntry sym.name
-                  while (prevEntry != null &&
+                  while ((prevEntry ne null) &&
                          !(prevEntry.sym == sym ||
                            prevEntry.sym.owner != sym.owner &&
                            !sym.hasFlag(PRIVATE) && {
-                             if (self == null) self = this.narrow;
+                             if (self eq null) self = this.narrow;
                              (self.memberType(prevEntry.sym) matches self.memberType(sym))
                            })) {
                     prevEntry = members lookupNextEntry prevEntry
                   }
-                  if (prevEntry == null) {
+                  if (prevEntry eq null) {
                     members enter sym
                   }
                 }
@@ -470,7 +470,7 @@ trait Types requires SymbolTable {
               }
             }
             entry = if (name == nme.ANYNAME) entry.next else decls lookupNextEntry entry
-          } // while (entry != null)
+          } // while (entry ne null)
           // excluded = excluded | LOCAL
         } // while (!bcs.isEmpty)
         excluded = excludedFlags
@@ -478,7 +478,7 @@ trait Types requires SymbolTable {
       checkMalformedSwitch = savedCheckMalformedSwitch
       if (util.Statistics.enabled)
         findMemberMillis = findMemberMillis + currentTime - startTime
-      if (members == null) {
+      if (members eq null) {
         if (util.Statistics.enabled) if (member == NoSymbol) noMemberCount = noMemberCount + 1;
         member
       } else {
@@ -679,7 +679,7 @@ trait Types requires SymbolTable {
             val index = new Array[int](nparents)
             var i = 0
             for (val p <- parents) {
-              pclosure(i) = if (p.closure == null) AnyClass.info.closure // cyclic reference
+              pclosure(i) = if (p.closure eq null) AnyClass.info.closure // cyclic reference
                             else p.closure
               index(i) = 0
               i = i + 1
@@ -747,7 +747,7 @@ trait Types requires SymbolTable {
         }
         //Console.println("closure(" + symbol + ") = " + List.fromArray(closureCache));//DEBUG
       }
-      if (closureCache == null)
+      if (closureCache eq null)
         throw new TypeError("illegal cyclic reference involving " + symbol)
       closureCache
     }
@@ -787,7 +787,7 @@ trait Types requires SymbolTable {
           baseClassesCache = computeBaseClasses
         }
       }
-      if (baseClassesCache == null)
+      if (baseClassesCache eq null)
         throw new TypeError("illegal cyclic reference involving " + symbol)
       baseClassesCache
     }
@@ -806,7 +806,7 @@ trait Types requires SymbolTable {
 
     override def toString(): String = (
       parents.mkString("", " with ", "") +
-      (if (settings.debug.value || parents.isEmpty || decls.elems != null)
+      (if (settings.debug.value || parents.isEmpty || (decls.elems ne null))
         decls.mkString("{", "; ", "}") else "")
     );
   }
@@ -848,8 +848,8 @@ trait Types requires SymbolTable {
     override def deconst: Type = value.tpe
     override def toString(): String =
       value.tpe.toString() + "(" + value.escapedStringValue + ")"
-    // override def isNullable: boolean = value.value == null
-    // override def isNonNull: boolean = value.value != null
+    // override def isNullable: boolean = value.value eq null
+    // override def isNonNull: boolean = value.value ne null
   }
 
   /** A class for named types of the form
@@ -1060,7 +1060,7 @@ trait Types requires SymbolTable {
   case class TypeVar(origin: Type, constr: TypeConstraint) extends Type {
     override def symbol = origin.symbol
     override def toString(): String =
-      if (constr.inst == null) "<null " + origin + ">"
+      if (constr.inst eq null) "<null " + origin + ">"
       else if (constr.inst eq NoType) "?" + origin
       else constr.inst.toString();
   }
@@ -1286,7 +1286,7 @@ trait Types requires SymbolTable {
       uniqueRunId = currentRunId
     }
     val tp1 = uniques.findEntry(tp)
-    if (tp1 == null) {
+    if (tp1 eq null) {
       uniques.addEntry(tp); tp
     } else {
       tp1.asInstanceOf[T]
@@ -1626,7 +1626,7 @@ trait Types requires SymbolTable {
     var result: Symbol = _
     def init = { result = NoSymbol }
     def apply(tp: Type): Type = {
-      assert(tp != null)
+      assert(tp ne null)
       tp match {
         case ThisType(sym) =>
           register(sym)
diff --git a/src/compiler/scala/tools/nsc/symtab/classfile/ClassfileParser.scala b/src/compiler/scala/tools/nsc/symtab/classfile/ClassfileParser.scala
index f005b53921..3640cbbb5e 100644
--- a/src/compiler/scala/tools/nsc/symtab/classfile/ClassfileParser.scala
+++ b/src/compiler/scala/tools/nsc/symtab/classfile/ClassfileParser.scala
@@ -143,7 +143,7 @@ abstract class ClassfileParser {
     def getName(index: int): Name = {
       if (index <= 0 || len <= index) errorBadIndex(index)
       var name = values(index).asInstanceOf[Name]
-      if (name == null) {
+      if (name eq null) {
         val start = starts(index)
         if (in.buf(start) != CONSTANT_UTF8) errorBadTag(start)
         name = newTermName(in.buf, start + 3, in.getChar(start + 1))
@@ -154,7 +154,7 @@ abstract class ClassfileParser {
 
     def getExternalName(index: int): Name = {
       if (index <= 0 || len <= index) errorBadIndex(index)
-      if (internalized(index) == null) {
+      if (internalized(index) eq null) {
         internalized(index) = getName(index).replace('/', '.')
       }
       internalized(index)
@@ -163,7 +163,7 @@ abstract class ClassfileParser {
     def getClassSymbol(index: int): Symbol = {
       if (index <= 0 || len <= index) errorBadIndex(index)
       var c = values(index).asInstanceOf[Symbol]
-      if (c == null) {
+      if (c eq null) {
         val start = starts(index)
         if (in.buf(start) != CONSTANT_CLASS) errorBadTag(start)
         val name = getExternalName(in.getChar(start + 1))
@@ -185,7 +185,7 @@ abstract class ClassfileParser {
     def getMemberSymbol(index: Int, static: Boolean): Symbol = {
       if (index <= 0 || len <= index) errorBadIndex(index)
       var f = values(index).asInstanceOf[Symbol]
-      if (f == null) {
+      if (f eq null) {
         val start = starts(index)
         if (in.buf(start) != CONSTANT_FIELDREF &&
             in.buf(start) != CONSTANT_METHODREF &&
@@ -215,7 +215,7 @@ abstract class ClassfileParser {
     def getNameAndType(index: Int, ownerClass: Symbol): Pair[Name, Type] = {
       if (index <= 0 || len <= index) errorBadIndex(index)
       var p = values(index).asInstanceOf[Pair[Name, Type]]
-      if (p == null) {
+      if (p eq null) {
         val start = starts(index)
         if (in.buf(start) != CONSTANT_NAMEANDTYPE) errorBadTag(start)
         val name = getName(in.getChar(start + 1))
@@ -239,7 +239,7 @@ abstract class ClassfileParser {
       if (index <= 0 || len <= index) errorBadIndex(index)
       val value = values(index)
       var c: Type = null
-      if (value == null) {
+      if (value eq null) {
         val start = starts(index)
         if (in.buf(start) != CONSTANT_CLASS) errorBadTag(start)
         val name = getExternalName(in.getChar(start + 1))
@@ -264,7 +264,7 @@ abstract class ClassfileParser {
     def getConstant(index: int): Constant = {
       if (index <= 0 || len <= index) errorBadIndex(index)
       var value = values(index)
-      if (value == null) {
+      if (value eq null) {
         val start = starts(index)
         value = in.buf(start) match {
           case CONSTANT_STRING =>
@@ -610,7 +610,7 @@ abstract class ClassfileParser {
         case nme.ConstantValueATTR =>
           val c = pool.getConstant(in.nextChar)
           val c1 = convertTo(c, symtype)
-          if (c1 != null) sym.setInfo(ConstantType(c1))
+          if (c1 ne null) sym.setInfo(ConstantType(c1))
           else Console.println("failure to convert " + c + " to " + symtype); //debug
         case nme.InnerClassesATTR =>
           if (!isScala) parseInnerClasses() else in.skip(attrLen)
@@ -625,9 +625,9 @@ abstract class ClassfileParser {
         case nme.SourceFileATTR =>
           assert(attrLen == 2)
           val source = pool.getName(in.nextChar)
-          if (sourcePath != null) {
+          if (sourcePath ne null) {
             val sourceFile0 = sourcePath.lookupPath(source.toString(), false)
-            if (sourceFile0 != null && clazz.sourceFile == null) {
+            if ((sourceFile0 ne null) && (clazz.sourceFile eq null)) {
               clazz.sourceFile = sourceFile0
             }
             staticModule.moduleClass.sourceFile = clazz.sourceFile
diff --git a/src/compiler/scala/tools/nsc/symtab/classfile/MetaParser.scala b/src/compiler/scala/tools/nsc/symtab/classfile/MetaParser.scala
index b5fc245c62..83b5147ef9 100644
--- a/src/compiler/scala/tools/nsc/symtab/classfile/MetaParser.scala
+++ b/src/compiler/scala/tools/nsc/symtab/classfile/MetaParser.scala
@@ -128,7 +128,7 @@ abstract class MetaParser{
 
   protected def parseMethod(): unit = {
     val globals = locals
-    locals = if (locals == null) newScope else newScope(locals);
+    locals = if (locals eq null) newScope else newScope(locals);
     def parse(): Type = {
       nextToken();
       if (token == "[") PolyType(parseTypeParams(), parse())
diff --git a/src/compiler/scala/tools/nsc/symtab/classfile/SymblfileParser.scala b/src/compiler/scala/tools/nsc/symtab/classfile/SymblfileParser.scala
index a9af8bb794..99d64a3018 100644
--- a/src/compiler/scala/tools/nsc/symtab/classfile/SymblfileParser.scala
+++ b/src/compiler/scala/tools/nsc/symtab/classfile/SymblfileParser.scala
@@ -25,7 +25,7 @@ abstract class SymblfileParser {
   }
 
   def parse(file: AbstractFile, root: Symbol): unit = {
-    assert(current == null, current)
+    assert(current eq null, current)
     current = file
     val bytes  = new AbstractFileReader(file).buf
     if (root.isModule)
diff --git a/src/compiler/scala/tools/nsc/symtab/classfile/UnPickler.scala b/src/compiler/scala/tools/nsc/symtab/classfile/UnPickler.scala
index 27f355007b..ed09bc2433 100644
--- a/src/compiler/scala/tools/nsc/symtab/classfile/UnPickler.scala
+++ b/src/compiler/scala/tools/nsc/symtab/classfile/UnPickler.scala
@@ -99,11 +99,11 @@ abstract class UnPickler {
      *  readIndex at start of i'th entry. Restore readIndex afterwards. */
     private def at[T <: AnyRef](i: int, op: () => T): T = {
       var r = entries(i)
-      if (r == null) {
+      if (r eq null) {
         val savedIndex = readIndex
         readIndex = index(i)
         r = op()
-        assert(entries(i) == null, entries(i))
+        assert(entries(i) eq null, entries(i))
         entries(i) = r
         readIndex = savedIndex
       }
diff --git a/src/compiler/scala/tools/nsc/transform/AddInterfaces.scala b/src/compiler/scala/tools/nsc/transform/AddInterfaces.scala
index b58d47ef05..37138d2638 100644
--- a/src/compiler/scala/tools/nsc/transform/AddInterfaces.scala
+++ b/src/compiler/scala/tools/nsc/transform/AddInterfaces.scala
@@ -77,7 +77,7 @@ abstract class AddInterfaces extends InfoTransform {
             atPhase(phase.next) {
               val decls = iface.owner.info.decls
               val e = decls.lookupEntry(impl.name)
-              if (e == null) {
+              if (e eq null) {
                 decls enter impl
               } else {
                 decls.unlink(e)
diff --git a/src/compiler/scala/tools/nsc/transform/Constructors.scala b/src/compiler/scala/tools/nsc/transform/Constructors.scala
index d0d77808ce..e7a8023c5f 100644
--- a/src/compiler/scala/tools/nsc/transform/Constructors.scala
+++ b/src/compiler/scala/tools/nsc/transform/Constructors.scala
@@ -47,7 +47,7 @@ abstract class Constructors extends Transform {
           case _ =>
         }
       }
-      assert(constr != null && constrBody != null, impl)
+      assert((constr ne null) && (constrBody ne null), impl)
 
       val paramAccessors = clazz.constrParamAccessors
 
diff --git a/src/compiler/scala/tools/nsc/transform/Erasure.scala b/src/compiler/scala/tools/nsc/transform/Erasure.scala
index f8a1335084..8bffb80b2b 100644
--- a/src/compiler/scala/tools/nsc/transform/Erasure.scala
+++ b/src/compiler/scala/tools/nsc/transform/Erasure.scala
@@ -536,10 +536,10 @@ abstract class Erasure extends AddInterfaces with typechecker.Analyzer {
 
       val decls = root.info.decls
       var e = decls.elems
-      while (e != null) {
+      while (e ne null) {
         if (e.sym.isTerm && !e.sym.isConstructor) {
           var e1 = decls.lookupNextEntry(e)
-          while (e1 != null) {
+          while (e1 ne null) {
             if (atPhase(phase.next)(e1.sym.info =:= e.sym.info)) doubleDefError(e.sym, e1.sym)
             e1 = decls.lookupNextEntry(e1)
           }
@@ -626,9 +626,9 @@ abstract class Erasure extends AddInterfaces with typechecker.Analyzer {
             !(other.tpe =:= member.tpe) &&
             !(deconstMap(other.tpe) =:= deconstMap(member.tpe)) &&
             { var e = bridgesScope.lookupEntry(member.name)
-              while (e != null && !((e.sym.tpe =:= otpe) && (bridgeTarget(e.sym) == member)))
+              while ((e ne null) && !((e.sym.tpe =:= otpe) && (bridgeTarget(e.sym) == member)))
                 e = bridgesScope.lookupNextEntry(e);
-              e == null
+              (e eq null)
             }
           );
           if (bridgeNeeded) {
@@ -742,7 +742,7 @@ abstract class Erasure extends AddInterfaces with typechecker.Analyzer {
             if (fn.symbol == Any_asInstanceOf || fn.symbol == Any_asInstanceOfErased)
               fn match {
                 case TypeApply(Select(qual, _), List(targ)) =>
-                  assert(qual.tpe != null, tree)
+                  assert(qual.tpe ne null, tree)
                   if (qual.tpe <:< targ.tpe) atPos(tree.pos) { Typed(qual, TypeTree(qual.tpe)) }
                   else tree
               }
diff --git a/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala b/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala
index 091c4e4655..d38c7e144a 100644
--- a/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala
+++ b/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala
@@ -49,8 +49,8 @@ abstract class ExplicitOuter extends InfoTransform with TransMatcher with Patter
     if (firstTry != NoSymbol && firstTry.outerSource == clazz) firstTry
     else {
       var e = clazz.info.decls.elems
-      while (e != null && e.sym.outerSource != clazz) e = e.next
-      if (e != null) e.sym else NoSymbol
+      while ((e ne null) && e.sym.outerSource != clazz) e = e.next
+      if (e ne null) e.sym else NoSymbol
     }
   }
 
@@ -309,7 +309,7 @@ abstract class ExplicitOuter extends InfoTransform with TransMatcher with Patter
     /** The main transformation method */
     override def transform(tree: Tree): Tree = {
       val sym = tree.symbol
-      if (sym != null && sym.isType) {//(9)
+      if ((sym ne null) && sym.isType) {//(9)
         if (sym hasFlag PRIVATE) sym setFlag notPRIVATE
         if (sym hasFlag PROTECTED) sym setFlag notPROTECTED
       }
diff --git a/src/compiler/scala/tools/nsc/transform/Mixin.scala b/src/compiler/scala/tools/nsc/transform/Mixin.scala
index c8d00acd59..e134c6b72c 100644
--- a/src/compiler/scala/tools/nsc/transform/Mixin.scala
+++ b/src/compiler/scala/tools/nsc/transform/Mixin.scala
@@ -561,7 +561,7 @@ abstract class Mixin extends InfoTransform {
       // change every node type that refers to an implementation class to its
       // corresponding interface, unless the node's symbol is an implementation class.
       if (tree.tpe.symbol.isImplClass &&
-          (tree.symbol == null || !tree.symbol.isImplClass))
+          ((tree.symbol eq null) || !tree.symbol.isImplClass))
         tree.tpe = toInterface(tree.tpe);
 
       tree match {
diff --git a/src/compiler/scala/tools/nsc/transform/OverridingPairs.scala b/src/compiler/scala/tools/nsc/transform/OverridingPairs.scala
index 444077f838..f170c132e7 100644
--- a/src/compiler/scala/tools/nsc/transform/OverridingPairs.scala
+++ b/src/compiler/scala/tools/nsc/transform/OverridingPairs.scala
@@ -56,7 +56,7 @@ abstract class OverridingPairs {
         if (!bcs.isEmpty) {
           fillDecls(bcs.tail, deferredflag)
           var e = bcs.head.info.decls.elems;
-          while (e != null) {
+          while (e ne null) {
             if (e.sym.getFlag(DEFERRED) == deferredflag && !exclude(e.sym))
               decls enter e.sym;
             e = e.next
@@ -102,29 +102,29 @@ abstract class OverridingPairs {
     var overriding: Symbol = _
     var overridden: Symbol = _
 
-    def hasNext: boolean = curEntry != null
+    def hasNext: boolean = curEntry ne null
 
     def next: unit =
-      if (curEntry != null) {
+      if (curEntry ne null) {
         overriding = curEntry.sym
-        if (nextEntry != null) {
+        if (nextEntry ne null) {
           do {
             nextEntry = decls.lookupNextEntry(nextEntry);
-          } while (nextEntry != null &&
+          } while ((nextEntry ne null) &&
                    ((nextEntry.sym hasFlag PRIVATE) ||
                     (overriding.owner == nextEntry.sym.owner) ||
                     (!matches(overriding, nextEntry.sym)) ||
                     (hasCommonParent(overriding, nextEntry.sym)) ||
                     (overriding hasFlag LOCAL)))
         }
-        if (nextEntry != null) {
+        if (nextEntry ne null) {
           overridden = nextEntry.sym;
           //Console.println("yield: " + overriding + overriding.locationString + " / " + overridden + overridden.locationString);//DEBUG
           visited addEntry nextEntry
         } else {
           do {
             curEntry = curEntry.next
-          } while (curEntry != null && (visited contains curEntry));
+          } while ((curEntry ne null) && (visited contains curEntry));
           nextEntry = curEntry
           next
         }
diff --git a/src/compiler/scala/tools/nsc/transform/UnCurry.scala b/src/compiler/scala/tools/nsc/transform/UnCurry.scala
index be832a0a49..668730f36e 100644
--- a/src/compiler/scala/tools/nsc/transform/UnCurry.scala
+++ b/src/compiler/scala/tools/nsc/transform/UnCurry.scala
@@ -370,7 +370,7 @@ abstract class UnCurry extends InfoTransform with TypingTransformers {
         }
         case Apply(fn, args) =>
           if (settings.noassertions.value &&
-              fn.symbol != null &&
+              (fn.symbol ne null) &&
               (fn.symbol.name == nme.assert_ || fn.symbol.name == nme.assume_) &&
               fn.symbol.owner == PredefModule.moduleClass) {
             Literal(()).setPos(tree.pos).setType(UnitClass.tpe)
diff --git a/src/compiler/scala/tools/nsc/typechecker/ConstantFolder.scala b/src/compiler/scala/tools/nsc/typechecker/ConstantFolder.scala
index adb314cf1e..21f8afe7ac 100644
--- a/src/compiler/scala/tools/nsc/typechecker/ConstantFolder.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/ConstantFolder.scala
@@ -41,7 +41,7 @@ abstract class ConstantFolder {
   private def fold(tree: Tree, compX: => Constant): Tree =
     try {
       val x = compX
-      if (x != null && x.tag != UnitTag) tree setType ConstantType(x)
+      if ((x ne null) && x.tag != UnitTag) tree setType ConstantType(x)
       else tree
     } catch {
       case _: ArithmeticException => tree   // the code will crash at runtime,
diff --git a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
index b33caf6d2a..7d13a8f347 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
@@ -38,7 +38,7 @@ trait Contexts requires Analyzer {
     import definitions._
     var sc = startContext
     def addImport(pkg: Symbol): unit = {
-      assert(pkg != null)
+      assert(pkg ne null)
       val qual = gen.mkAttributedStableRef(pkg)
       sc = sc.makeNewImport(
         Import(qual, List(Pair(nme.WILDCARD, null)))
@@ -49,7 +49,7 @@ trait Contexts requires Analyzer {
     if (!settings.noimports.value) {
       assert(isDefinitionsInitialized)
       addImport(JavaLangPackage)
-      assert(ScalaPackage != null, "Scala package is null")
+      assert(ScalaPackage ne null, "Scala package is null")
       addImport(ScalaPackage)
       if (!settings.nopredefs.value/* || unit.source.file.name != "Predef.scala"*/)
         addImport(PredefModule)
@@ -101,7 +101,7 @@ trait Contexts requires Analyzer {
       case that if (super.equals(that)) => true
       case NoContext => false
       case that : Context =>
-        val a0 = if (tree == null) tree == that.tree else tree equalsStructure that.tree;
+        val a0 = if (tree eq null) tree == that.tree else tree equalsStructure that.tree;
         val a1 = owner == that.owner;
         val a2 = scope == that.scope;
         val a3 = outer == that.outer;
@@ -326,8 +326,8 @@ trait Contexts requires Analyzer {
       def accessWithin(owner: Symbol): boolean = {
         var c = this
         while (c != NoContext && c.owner != owner) {
-          if (c.outer == null) assert(false, "accessWithin(" + owner + ") " + c);//debug
-          if (c.outer.enclClass == null) assert(false, "accessWithin(" + owner + ") " + c);//debug
+          if (c.outer eq null) assert(false, "accessWithin(" + owner + ") " + c);//debug
+          if (c.outer.enclClass eq null) assert(false, "accessWithin(" + owner + ") " + c);//debug
           c = c.outer.enclClass
         }
         c != NoContext
@@ -462,7 +462,7 @@ trait Contexts requires Analyzer {
   class ImplicitInfo(val name: Name, val pre: Type, val sym: Symbol) {
     private var tpeCache: Type = null
     def tpe: Type = {
-      if (tpeCache == null) tpeCache = pre.memberType(sym)
+      if (tpeCache eq null) tpeCache = pre.memberType(sym)
       tpeCache
     }
     override def toString = "ImplicitInfo(" + name + "," + pre + "," + sym + ")"
diff --git a/src/compiler/scala/tools/nsc/typechecker/Infer.scala b/src/compiler/scala/tools/nsc/typechecker/Infer.scala
index a758f8abe6..93be3da36c 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Infer.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Infer.scala
@@ -137,7 +137,7 @@ trait Infer requires Analyzer {
               ((bound contains tparam2) ||
                up && (tparam2.info.bounds.lo =:= tparam.tpe) ||
                !up && (tparam2.info.bounds.hi =:= tparam.tpe))) {
-            if (tvar2.constr.inst == null) cyclic = true
+            if (tvar2.constr.inst eq null) cyclic = true
             solveOne(tvar2, tparam2, variance2)
           }
         }
@@ -221,7 +221,7 @@ trait Infer requires Analyzer {
       (if (name.isTypeName) "type " else "value ") + name.decode
 
     def treeSymTypeMsg(tree: Tree): String =
-      if (tree.symbol == null)
+      if (tree.symbol eq null)
         "expression of type " + tree.tpe
       else if (tree.symbol.hasFlag(OVERLOADED))
         "overloaded method " + tree.symbol + " with alternatives " + tree.tpe
@@ -326,7 +326,7 @@ trait Infer requires Analyzer {
         sym.toplevelClass match {
           case clazz : ClassSymbol =>
             // System.err.println("TOP: " + clazz + " " + clazz.sourceFile)
-            if (clazz.sourceFile != null)
+            if (clazz.sourceFile ne null)
               global.currentRun.currentUnit.depends += clazz.sourceFile
 
           case _ =>
@@ -524,7 +524,7 @@ trait Infer requires Analyzer {
               val uninstantiated = new ListBuffer[Symbol]
               val targs = methTypeArgs(undetparams, formals, restpe, argtpes, pt, uninstantiated)
               val result = (
-                exprTypeArgs(uninstantiated.toList, restpe.subst(undetparams, targs), pt) != null &&
+                (exprTypeArgs(uninstantiated.toList, restpe.subst(undetparams, targs), pt) ne null) &&
                 isWithinBounds(undetparams, targs)
               )
               result
@@ -602,7 +602,7 @@ trait Infer requires Analyzer {
     def inferArgumentInstance(tree: Tree, undetparams: List[Symbol],
                               strictPt: Type, lenientPt: Type): unit = {
       var targs = exprTypeArgs(undetparams, tree.tpe, strictPt)
-      if (targs == null) targs = exprTypeArgs(undetparams, tree.tpe, lenientPt)
+      if (targs eq null) targs = exprTypeArgs(undetparams, tree.tpe, lenientPt)
       substExpr(tree, undetparams, targs, lenientPt)
     }
 
@@ -626,7 +626,7 @@ trait Infer requires Analyzer {
      */
     private def substExpr(tree: Tree, undetparams: List[Symbol],
                           targs: List[Type], pt: Type): unit =
-      if (targs == null) {
+      if (targs eq null) {
         if (!tree.tpe.isErroneous && !pt.isErroneous)
           error(tree.pos, "polymorphic expression cannot be instantiated to expected type" +
                 foundReqMsg(PolyType(undetparams, skipImplicit(tree.tpe)), pt))
@@ -793,7 +793,7 @@ trait Infer requires Analyzer {
         sym.isAbstractType &&
         (sym.name == nme.WILDCARD.toTypeName || {
           val e = context.scope.lookupEntry(sym.name)
-          e != null && e.sym == sym && e.owner == context.scope
+          (e ne null) && e.sym == sym && e.owner == context.scope
         })
       tp match {
         case SingleType(pre, _) =>
diff --git a/src/compiler/scala/tools/nsc/typechecker/Namers.scala b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
index b01227da01..c527bb981b 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Namers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
@@ -83,7 +83,7 @@ trait Namers requires Analyzer {
     def namerOf(sym: Symbol): Namer = {
 
       def innerNamer: Namer = {
-        if (innerNamerCache == null)
+        if (innerNamerCache eq null)
           innerNamerCache =
             if (!isTemplateContext(context)) this
             else new Namer(context.make(context.tree, context.owner, newScope))
@@ -114,7 +114,7 @@ trait Namers requires Analyzer {
       // allow for overloaded methods
       if (!(sym.isSourceMethod && sym.owner.isClass && !sym.owner.isPackageClass)) {
       	val prev = context.scope.lookupEntry(sym.name);
-      	if (prev != null && prev.owner == context.scope &&
+      	if ((prev ne null) && prev.owner == context.scope &&
             (!prev.sym.isSourceMethod ||
              nme.isSetterName(sym.name) ||
              sym.owner.isPackageClass)) {
@@ -154,11 +154,11 @@ trait Namers requires Analyzer {
       if (c.owner.isPackageClass) {
       	val file = context.unit.source.getFile()
       	val clazz = c.asInstanceOf[ClassSymbol]
-      	if (settings.debug.value && clazz.sourceFile != null && !clazz.sourceFile.equals(file)) {
+      	if (settings.debug.value && (clazz.sourceFile ne null) && !clazz.sourceFile.equals(file)) {
           Console.err.println("SOURCE MISMATCH: " + clazz.sourceFile + " vs. " + file + " SYM=" + c);
         }
         clazz.sourceFile = file
-        if (clazz.sourceFile != null) {
+        if (clazz.sourceFile ne null) {
           assert(!currentRun.compiles(clazz) || clazz.sourceFile == currentRun.symSource(c));
           currentRun.symSource(c) = clazz.sourceFile
         }
@@ -596,14 +596,14 @@ trait Namers requires Analyzer {
               typer.checkStable(expr1)
               def checkNotRedundant(pos: PositionType, from: Name, to: Name): boolean = {
                 if (!tree.symbol.hasFlag(SYNTHETIC) &&
-                    !(expr1.symbol != null && expr1.symbol.isInterpreterWrapper) &&
+                    !((expr1.symbol ne null) && expr1.symbol.isInterpreterWrapper) &&
                     base.member(from) != NoSymbol) {
                   val e = context.scope.lookupEntry(to)
                   def warnRedundant(sym: Symbol) =
                     context.unit.warning(pos, "imported `"+to+
                                          "' is permanently hidden by definition of "+sym+
                                          sym.locationString)
-                  if (e != null && e.owner == context.scope) {
+                  if ((e ne null) && e.owner == context.scope) {
                     warnRedundant(e.sym); return false
                   } else if (context eq context.enclClass) {
                     val defSym = context.prefix.member(to) filter (
@@ -623,7 +623,7 @@ trait Namers requires Analyzer {
                   }
         	  if (from != nme.WILDCARD && (rest.exists (sel => sel._1 == from)))
         	    context.error(tree.pos, from.decode + " is renamed twice");
-        	  if (to != null && to != nme.WILDCARD && (rest exists (sel => sel._2 == to)))
+        	  if ((to ne null) && to != nme.WILDCARD && (rest exists (sel => sel._2 == to)))
         	    context.error(tree.pos, to.decode + " appears twice as a target of a renaming");
         	  checkSelectors(rest)
                 case Nil =>
diff --git a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
index 728cca7453..e2c04090da 100644
--- a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
@@ -278,7 +278,7 @@ abstract class RefChecks extends InfoTransform {
 	if (baseClass.isClass) {
 	  val index = clazz.info.closurePos(baseClass)
 	  if (index >= 0) {
-	    if (seenTypes(index) != null && !(seenTypes(index) <:< tp))
+	    if ((seenTypes(index) ne null) && !(seenTypes(index) <:< tp))
 	      unit.error(clazz.pos, "illegal inheritance;\n " + clazz +
 			 " inherits different type instances of " + baseClass +
 			 ":\n" + tp + " and " + seenTypes(index));
@@ -382,7 +382,7 @@ abstract class RefChecks extends InfoTransform {
 // Forward reference checking ---------------------------------------------------
 
     class LevelInfo(val outer: LevelInfo) {
-      val scope: Scope = if (outer == null) newScope else newScope(outer.scope)
+      val scope: Scope = if (outer eq null) newScope else newScope(outer.scope)
       var maxindex: int = MIN_INT
       var refpos: int = _
       var refsym: Symbol = _
@@ -416,7 +416,7 @@ abstract class RefChecks extends InfoTransform {
     private def enterReference(pos: int, sym: Symbol): unit =
       if (sym.isLocal) {
 	val e = currentLevel.scope.lookupEntry(sym.name)
-	if (e != null && sym == e.sym) {
+	if ((e ne null) && sym == e.sym) {
           var l = currentLevel
           while (l.scope != e.owner) l = l.outer;
 	  val symindex = symIndex(sym)
diff --git a/src/compiler/scala/tools/nsc/typechecker/TreeCheckers.scala b/src/compiler/scala/tools/nsc/typechecker/TreeCheckers.scala
index dd24c7b32e..d2d0d64805 100644
--- a/src/compiler/scala/tools/nsc/typechecker/TreeCheckers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/TreeCheckers.scala
@@ -95,7 +95,7 @@ abstract class TreeCheckers extends Analyzer {
           }
           if (tree.pos == NoPos && tree != EmptyTree) {
             error(tree.pos, "tree without position: " + tree)
-          } else if (tree.tpe == null && phase.id >= currentRun.typerPhase.id) {
+          } else if ((tree.tpe eq null) && phase.id >= currentRun.typerPhase.id) {
             error(tree.pos, "tree without type: " + tree)
           } else if (tree.isDef && tree.symbol.owner != currentOwner) {
             var owner = currentOwner
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index 35a728dbbb..1b1b1823a3 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -176,7 +176,7 @@ trait Typers requires Analyzer {
 
     private var namerCache: Namer = null
     def namer = {
-      if (namerCache == null || namerCache.context != context)
+      if ((namerCache eq null) || namerCache.context != context)
         namerCache = new Namer(context)
       namerCache
     }
@@ -196,9 +196,9 @@ trait Typers requires Analyzer {
         case CyclicReference(sym, info: TypeCompleter) =>
           val msg =
             info.tree match {
-              case ValDef(_, _, tpt, _) if (tpt.tpe == null) =>
+              case ValDef(_, _, tpt, _) if (tpt.tpe eq null) =>
                 "recursive "+sym+" needs type"
-              case DefDef(_, _, _, _, tpt, _) if (tpt.tpe == null) =>
+              case DefDef(_, _, _, _, tpt, _) if (tpt.tpe eq null) =>
                 (if (sym.owner.isClass && sym.owner.info.member(sym.name).hasFlag(OVERLOADED)) "overloaded "
                  else "recursive ")+sym+" needs result type"
               case _ =>
@@ -321,7 +321,7 @@ trait Typers requires Analyzer {
         this.owner = owner
         this.scope = scope
         badSymbol = NoSymbol
-        assert(tree.tpe != null, tree)//debug
+        assert(tree.tpe ne null, tree)//debug
         apply(tree.tpe)
         if (badSymbol == NoSymbol) tree
         else if (badSymbol.isErroneous) setError(tree)
@@ -368,7 +368,7 @@ trait Typers requires Analyzer {
             if (o == sym.owner) badSymbol = sym
           } else if (sym.owner.isTerm && !sym.isTypeParameterOrSkolem) {
             var e = scope.lookupEntry(sym.name)
-            while (e != null && e.owner == scope && badSymbol == NoSymbol) {
+            while ((e ne null) && e.owner == scope && badSymbol == NoSymbol) {
               if (e.sym == sym) badSymbol = e.sym
               e = scope.lookupNextEntry(e)
             }
@@ -620,7 +620,7 @@ trait Typers requires Analyzer {
         } else if (tree.tpe <:< pt) {
           tree
         } else if ((mode & PATTERNmode) != 0) {
-          if (tree.symbol != null && tree.symbol.isModule) inferModulePattern(tree, pt)
+          if ((tree.symbol ne null) && tree.symbol.isModule) inferModulePattern(tree, pt)
           tree
         } else {
           val tree1 = constfold(tree, pt) // (10) (11)
@@ -678,7 +678,7 @@ trait Typers requires Analyzer {
      */
     def adaptToMember(qual: Tree, name: Name, tp: Type): Tree = {
       val qtpe = qual.tpe.widen
-      if (qual.isTerm && (qual.symbol == null || !qual.symbol.isTerm || qual.symbol.isValue) &&
+      if (qual.isTerm && ((qual.symbol eq null) || !qual.symbol.isTerm || qual.symbol.isValue) &&
           phase.id <= currentRun.typerPhase.id && !qtpe.isError && !tp.isError &&
           qtpe.symbol != AllRefClass && qtpe.symbol != AllClass && qtpe != WildcardType) {
         val coercion = inferView(qual.pos, qtpe, name, tp, true)
@@ -708,7 +708,7 @@ trait Typers requires Analyzer {
         var supertpt = typedTypeConstructor(templ.parents.head)
         var mixins = templ.parents.tail map typedType
         // If first parent is a trait, make it first mixin and add its superclass as first parent
-        while (supertpt.tpe.symbol != null && supertpt.tpe.symbol.initialize.isTrait) {
+        while ((supertpt.tpe.symbol ne null) && supertpt.tpe.symbol.initialize.isTrait) {
           val supertpt1 = typedType(supertpt)
           if (!supertpt1.tpe.isError) {
             mixins = supertpt1 :: mixins
@@ -952,7 +952,7 @@ trait Typers requires Analyzer {
           Pair(call, List())
       }
       val Pair(superConstr, superArgs) = decompose(rhs)
-      assert(superConstr.symbol != null)//debug
+      assert(superConstr.symbol ne null)//debug
       if (superConstr.symbol.isPrimaryConstructor) {
         val superClazz = superConstr.symbol.owner
         if (!superClazz.hasFlag(JAVA)) {
@@ -1247,7 +1247,7 @@ trait Typers requires Analyzer {
         stat match {
           case imp @ Import(_, _) =>
             val imp0 = typedImport(imp)
-            if (imp0 != null) {
+            if (imp0 ne null) {
               context = context.makeNewImport(imp0)
               imp0.symbol.initialize
             }
@@ -1261,10 +1261,10 @@ trait Typers requires Analyzer {
       def checkNoDoubleDefs(stats: List[Tree]) = {
         val scope = if (inBlock) context.scope else context.owner.info.decls;
         var e = scope.elems;
-        while (e != null && e.owner == scope) {
+        while ((e ne null) && e.owner == scope) {
           if (!e.sym.hasFlag(LOCAL)) {
             var e1 = scope.lookupNextEntry(e);
-            while (e1 != null && e1.owner == scope) {
+            while ((e1 ne null) && e1.owner == scope) {
               if (!e1.sym.hasFlag(LOCAL) &&
                   (e.sym.isType || inBlock || (e.sym.tpe matches e1.sym.tpe)))
                 if (!e.sym.isErroneous && !e1.sym.isErroneous)
@@ -1572,7 +1572,7 @@ trait Typers requires Analyzer {
           val Select(qual, name) = fun
           val args1 = tryTypedArgs(args)
           val qual1 =
-            if (args1 != null && !pt.isError) {
+            if ((args1 ne null) && !pt.isError) {
               def templateArgType(arg: Tree) =
                 new BoundedWildcardType(TypeBounds(arg.tpe, AnyClass.tpe))
               adaptToMember(qual, name, MethodType(args1 map templateArgType, pt))
@@ -1605,7 +1605,7 @@ trait Typers requires Analyzer {
             context.reportGeneralErrors = reportGeneralErrors
             def templateArgType(arg: Tree) =
               new BoundedWildcardType(TypeBounds(arg.tpe, AnyClass.tpe))
-            val qual1 = if (args1 == null || pt.isError) qual
+            val qual1 = if ((args1 eq null) || pt.isError) qual
                         else adaptToMember(qual, name, MethodType(args1 map templateArgType, pt))
             val tree1 = Apply(Select(qual1, name) setPos fun.pos, args map (arg => UnTyper.apply(arg))) setPos tree.pos
             typed1(tree1, mode | SNDTRYmode, pt)
@@ -1650,10 +1650,10 @@ trait Typers requires Analyzer {
         if (!sym.exists) {
           if (settings.debug.value) Console.err.println("qual = "+qual+":"+qual.tpe+"\nSymbol="+qual.tpe.symbol+"\nsymbol-info = "+qual.tpe.symbol.info+"\nscope-id = "+qual.tpe.symbol.info.decls.hashCode()+"\nmembers = "+qual.tpe.members+"\nname = "+name+"\nfound = "+sym+"\nowner = "+context.enclClass.owner)
           if (!qual.tpe.widen.isErroneous) {
-            if (false && context.unit == null) assert(false, "("+qual+":"+qual.tpe+")."+name)
+            if (false && (context.unit eq null)) assert(false, "("+qual+":"+qual.tpe+")."+name)
             error(tree.pos,
               decode(name)+" is not a member of "+qual.tpe.widen +
-              (if (context.unit != null && Position.line(context.unit.source, qual.pos) <
+              (if ((context.unit ne null) && Position.line(context.unit.source, qual.pos) <
                    Position.line(context.unit.source, tree.pos))
                 "\npossible cause: maybe a semicolon is missing before `"+name+"'?"
                else ""))
@@ -1680,7 +1680,7 @@ trait Typers requires Analyzer {
         while (cx != NoContext) {
           val pre = cx.enclClass.prefix
           val defEntry = cx.scope.lookupEntry(name)
-          if (defEntry != null && defEntry.sym.exists) return true
+          if ((defEntry ne null) && defEntry.sym.exists) return true
           cx = cx.enclClass
           if ((pre.member(name) filter (
             sym => sym.exists && context.isAccessible(sym, pre, false))) != NoSymbol) return true
@@ -1716,7 +1716,7 @@ trait Typers requires Analyzer {
           while (defSym == NoSymbol && cx != NoContext) {
             pre = cx.enclClass.prefix
             defEntry = cx.scope.lookupEntry(name)
-            if (defEntry != null && defEntry.sym.exists) {
+            if ((defEntry ne null) && defEntry.sym.exists) {
               defSym = defEntry.sym
             } else {
               cx = cx.enclClass
@@ -1726,7 +1726,7 @@ trait Typers requires Analyzer {
             }
           }
 
-          val symDepth = if (defEntry == null) cx.depth
+          val symDepth = if (defEntry eq null) cx.depth
                          else cx.depth - (cx.scope.nestingLevel - defEntry.owner.nestingLevel)
           var impSym: Symbol = NoSymbol;      // the imported symbol
           var imports = context.imports;      // impSym != NoSymbol => it is imported from imports.head
@@ -1745,7 +1745,7 @@ trait Typers requires Analyzer {
           if (defSym.exists && impSym.exists &&
               defSym.owner.isPackageClass &&
               (!currentRun.compiles(defSym) ||
-               context.unit != null && defSym.sourceFile != context.unit.source.file))
+               (context.unit ne null) && defSym.sourceFile != context.unit.source.file))
             defSym = NoSymbol
 
           /*<unapply>*/
@@ -1825,7 +1825,7 @@ trait Typers requires Analyzer {
 
       // begin typed1
       val sym: Symbol = tree.symbol
-      if (sym != null) sym.initialize
+      if (sym ne null) sym.initialize
       //if (settings.debug.value && tree.isDef) log("typing definition of "+sym);//DEBUG
       tree match {
         case PackageDef(name, stats) =>
@@ -1862,7 +1862,7 @@ trait Typers requires Analyzer {
 
         case DocDef(comment, defn) => {
           val ret = typed(defn, mode, pt)
-          if (comments != null) comments(defn . symbol) = comment;
+          if (comments ne null) comments(defn . symbol) = comment;
           ret
         }
         case tree @ Block(_, _) =>
@@ -1938,7 +1938,7 @@ trait Typers requires Analyzer {
           }
           val lhs1 = typed(lhs, EXPRmode | LHSmode, WildcardType)
           val varsym = lhs1.symbol
-          if (varsym != null && mayBeVarGetter(varsym)) {
+          if ((varsym ne null) && mayBeVarGetter(varsym)) {
             lhs1 match {
               case Select(qual, name) =>
                 typed(
@@ -1946,7 +1946,7 @@ trait Typers requires Analyzer {
                     Select(qual, nme.getterToSetter(name)) setPos lhs.pos,
                     List(rhs)) setPos tree.pos, mode, pt)
             }
-          } else if (varsym != null && (varsym.isVariable || varsym.isValue && phase.erasedTypes)) {
+          } else if ((varsym ne null) && (varsym.isVariable || varsym.isValue && phase.erasedTypes)) {
             val rhs1 = typed(rhs, lhs1.tpe)
             copy.Assign(tree, lhs1, rhs1) setType UnitClass.tpe
           } else {
@@ -1976,7 +1976,7 @@ trait Typers requires Analyzer {
             errorTree(tree, "return outside method definition")
           } else {
             val DefDef(_, _, _, _, restpt, _) = enclMethod.tree
-            if (restpt.tpe == null) {
+            if (restpt.tpe eq null) {
               errorTree(tree, "method " + enclMethod.owner +
                         " has return statement; needs result type")
             } else {
@@ -2049,7 +2049,7 @@ trait Typers requires Analyzer {
           typed1(atPos(tree.pos)(Block(stats, Apply(expr, args))), mode, pt)
 
         case Apply(fun, args) =>
-          val stableApplication = fun.symbol != null && fun.symbol.isMethod && fun.symbol.isStable
+          val stableApplication = (fun.symbol ne null) && fun.symbol.isMethod && fun.symbol.isStable
           if (stableApplication && (mode & PATTERNmode) != 0) {
             // treat stable function applications f() as expressions.
             typed1(tree, mode & ~PATTERNmode | EXPRmode, pt)
@@ -2063,7 +2063,7 @@ trait Typers requires Analyzer {
             if (phase.id <= currentRun.typerPhase.id &&
                 fun1.isInstanceOf[Select] &&
                 !fun1.tpe.isInstanceOf[ImplicitMethodType] &&
-                (fun1.symbol == null || !fun1.symbol.isConstructor) &&
+                ((fun1.symbol eq null) || !fun1.symbol.isConstructor) &&
                 (mode & (EXPRmode | SNDTRYmode)) == EXPRmode) tryTypedApply(fun1, args)
             else {
               typedApply(tree, fun1, args, mode, pt)
@@ -2203,14 +2203,14 @@ trait Typers requires Analyzer {
     def typed(tree: Tree, mode: int, pt: Type): Tree =
       try {
         if (settings.debug.value)
-          assert(pt != null, tree)//debug
+          assert(pt ne null, tree)//debug
         if (context.retyping &&
-            tree.tpe != null && (tree.tpe.isErroneous || !(tree.tpe <:< pt))) {
+            (tree.tpe ne null) && (tree.tpe.isErroneous || !(tree.tpe <:< pt))) {
           tree.tpe = null
           if (tree.hasSymbol) tree.symbol = NoSymbol
         }
         //Console.println("typing "+tree+", "+context.undetparams);//DEBUG
-        val tree1 = if (tree.tpe != null) tree else typed1(tree, mode, pt)
+        val tree1 = if (tree.tpe ne null) tree else typed1(tree, mode, pt)
         //Console.println("typed "+tree1+":"+tree1.tpe+", "+context.undetparams);//DEBUG
         val result = if (tree1.isEmpty) tree1 else adapt(tree1, mode, pt)
         //Console.println("adapted "+tree1+":"+tree1.tpe+" to "+pt+", "+context.undetparams);//DEBUG
@@ -2224,8 +2224,8 @@ trait Typers requires Analyzer {
         case ex: Throwable =>
           if (settings.debug.value)
             Console.println("exception when typing "+tree+", pt = "+pt)
-          if (context != null && context.unit != null &&
-              context.unit.source != null && tree != null)
+          if ((context ne null) && (context.unit ne null) &&
+              (context.unit.source ne null) && (tree ne null))
             logError("AT: " + context.unit.source.dbg(tree.pos), ex);
           throw(ex)
       }
diff --git a/src/compiler/scala/tools/nsc/util/ClassPath.scala b/src/compiler/scala/tools/nsc/util/ClassPath.scala
index a2ec9d945b..e01c577a65 100644
--- a/src/compiler/scala/tools/nsc/util/ClassPath.scala
+++ b/src/compiler/scala/tools/nsc/util/ClassPath.scala
@@ -43,13 +43,13 @@ class ClassPath(onlyPresentation: Boolean) {
   }
 
   class Output(location0: AbstractFile, val sourceFile: AbstractFile) extends Entry(location0) {
-    def source = if (sourceFile != null) new Source(sourceFile, true) else null
+    def source = if (sourceFile ne null) new Source(sourceFile, true) else null
   }
 
   class Library(location0: AbstractFile) extends Entry(location0) {
     def doc: AbstractFile = null
     def sourceFile: AbstractFile = null
-    def source = if (sourceFile == null) null else new Source(sourceFile, false)
+    def source = if (sourceFile eq null) null else new Source(sourceFile, false)
   }
 
   class Context(val entries: List[Entry]) {
@@ -60,24 +60,24 @@ class ClassPath(onlyPresentation: Boolean) {
           val ret = find0(entries.tail)
           val head = entries.head
           val name0 = name + (if (!isDir) ".class" else "")
-          val clazz = if (head.location == null) null
+          val clazz = if (head.location eq null) null
                       else head.location.lookupPath(name0, isDir)
 
           val source0 =
-            if (head.source == null) null
-            else if (clazz == null || isDir) {
+            if (head.source eq null) null
+            else if ((clazz eq null) || isDir) {
               val source1 = head.source.location.lookupPath(
                 name + (if (isDir) "" else ".scala"), isDir)
-              if (source1 == null && !isDir && clazz != null) head.source.location
+              if ((source1 eq null) && !isDir && (clazz ne null)) head.source.location
               else source1
             }
             else head.source.location
 
-          if (clazz == null && source0 == null) ret
+          if ((clazz eq null) && (source0 eq null)) ret
           else {
             val entry = new Entry(clazz) {
               override def source =
-                if (source0 == null) null
+                if (source0 eq null) null
                 else new Source(source0, head.source.compile)
             }
             try {
@@ -100,14 +100,14 @@ class ClassPath(onlyPresentation: Boolean) {
 
     def isPackage: Boolean =
       if (entries.isEmpty) false
-      else if (entries.head.location != null) entries.head.location.isDirectory
+      else if (entries.head.location ne null) entries.head.location.isDirectory
       else entries.head.source.location.isDirectory
 
     def name =
       if (entries.isEmpty) "<none>"
       else {
         val head = entries.head
-        val name = if (head.location != null) head.location.name
+        val name = if (head.location ne null) head.location.name
                    else head.source.location.name
         if (isPackage) name
         else name.substring(0, name.length() - (".class").length())
@@ -116,9 +116,9 @@ class ClassPath(onlyPresentation: Boolean) {
     override def toString(): String = toString(entries)
 
     def toString(entry: Entry): String =
-      ((if (entry.location == null) "<none>"
+      ((if (entry.location eq null) "<none>"
         else entry.location.toString()) +
-       (if (entry.source == null) ""
+       (if (entry.source eq null) ""
         else " with_source=" + entry.source.location.toString()))
 
     def toString(entries0: List[Entry]): String =
@@ -128,27 +128,27 @@ class ClassPath(onlyPresentation: Boolean) {
     def isSourceFile = {
       def head = entries.head
       def clazz = head.location
-      def source = if (head.source == null) null else head.source.location
+      def source = if (head.source eq null) null else head.source.location
       def isPredef = source.name.equals("Predef.scala") ||
                      source.path.startsWith("scala/runtime")
 
-      if (entries.isEmpty || entries.isEmpty || source == null) false
+      if (entries.isEmpty || entries.isEmpty || (source eq null)) false
       else if (!onlyPresentation && !head.source.compile) false
       else if (source.isDirectory) false
-      else if (clazz == null) true
+      else if (clazz eq null) true
       else if (onlyPresentation && !isPredef) true
       else if (source.lastModified > clazz.lastModified) true
       else false
     }
 
-    def sourceFile = if (entries.head.source != null && !entries.head.source.location.isDirectory)
+    def sourceFile = if ((entries.head.source ne null) && !entries.head.source.location.isDirectory)
       entries.head.source.location else null
 
     def classFile = if (!isSourceFile) entries.head.location else null
 
     {
       val sourcePath0 = sourcePath
-      if (sourcePath0 != null) {
+      if (sourcePath0 ne null) {
         if (!sourcePath0.isDirectory) {
           Console.err.println(""+sourcePath0 + " cannot be a directory")
           assert(false)
@@ -157,7 +157,7 @@ class ClassPath(onlyPresentation: Boolean) {
     }
 
     def sourcePath =
-      if (!isSourceFile && !entries.isEmpty && entries.head.source != null) {
+      if (!isSourceFile && !entries.isEmpty && (entries.head.source ne null)) {
         val ret = entries.head.source.location
         ret
       }
@@ -183,7 +183,7 @@ class ClassPath(onlyPresentation: Boolean) {
       addFilesInPath(boot)
       addArchivesInExtDirPath(extdirs)
       val clazzes = AbstractFile.getDirectory(output)
-      if (clazzes == null) {
+      if (clazzes eq null) {
         Console.err.println("Output location \"" + output + "\" not found")
         exit(1)
       }
@@ -207,9 +207,9 @@ class ClassPath(onlyPresentation: Boolean) {
      */
     def lookupPath(path: String, isDir: Boolean) = {
       val ctx = root.find(path, isDir)
-      if (ctx == null) null
+      if (ctx eq null) null
       else if (ctx.entries.isEmpty) null
-      else if (ctx.entries.head == null) null
+      else if (ctx.entries.head eq null) null
       else ctx.entries.head.location
     }
 
@@ -218,10 +218,10 @@ class ClassPath(onlyPresentation: Boolean) {
      *  @param sources ...
      */
     def library(classes: String, sources: String) = {
-      assert(classes != null)
+      assert(classes ne null)
       val location = AbstractFile.getDirectory(classes)
       val sourceFile0 =
-        if (sources != null) AbstractFile.getDirectory(sources)
+        if (sources ne null) AbstractFile.getDirectory(sources)
         else null
       class Library0 extends Library(location) {
         override def sourceFile = sourceFile0
@@ -233,7 +233,7 @@ class ClassPath(onlyPresentation: Boolean) {
       val strtok = new StringTokenizer(path, File.pathSeparator)
       while (strtok.hasMoreTokens()) {
         val file = AbstractFile.getDirectory(strtok.nextToken())
-        if (file != null) entries += (new Library(file))
+        if (file ne null) entries += (new Library(file))
       }
     }
 
@@ -241,12 +241,12 @@ class ClassPath(onlyPresentation: Boolean) {
       val strtok = new StringTokenizer(path, File.pathSeparator)
       while (strtok.hasMoreTokens()) {
         val file = AbstractFile.getDirectory(strtok.nextToken())
-        if (file != null) {
+        if (file ne null) {
           for (val file0 <- file) {
             val name = file0.name
             if (name.endsWith(".jar") || name.endsWith(".zip") || file0.isDirectory) {
               val archive = AbstractFile.getDirectory(new File(file.file, name))
-              if (archive != null) entries += (new Library(archive))
+              if (archive ne null) entries += (new Library(archive))
             }
           }
         }
diff --git a/src/compiler/scala/tools/nsc/util/HashSet.scala b/src/compiler/scala/tools/nsc/util/HashSet.scala
index 2b2b8bdc53..fea6e8886e 100644
--- a/src/compiler/scala/tools/nsc/util/HashSet.scala
+++ b/src/compiler/scala/tools/nsc/util/HashSet.scala
@@ -19,7 +19,7 @@ class HashSet[T >: Null <: AnyRef](initialCapacity: int) extends Set[T] {
   def findEntry(x: T): T = {
     var h = x.hashCode() % capacity
     var entry = table(h)
-    while (entry != null && entry != x) {
+    while ((entry ne null) && entry != x) {
       h = (h + 1) % capacity
       entry = table(h)
     }
@@ -29,7 +29,7 @@ class HashSet[T >: Null <: AnyRef](initialCapacity: int) extends Set[T] {
   def addEntry(x: T): unit = {
     var h = x.hashCode() % capacity
     var entry = table(h)
-    while (entry != null) {
+    while (entry ne null) {
       if (entry == x) return
       h = (h + 1) % capacity
       entry = table(h)
@@ -42,7 +42,7 @@ class HashSet[T >: Null <: AnyRef](initialCapacity: int) extends Set[T] {
   def elements = new Iterator[T] {
     private var i = 0
     def hasNext: boolean = {
-      while (i < capacity && table(i) == null) i = i + 1;
+      while (i < capacity && (table(i) eq null)) i = i + 1;
       i < capacity
     }
     def next: T =
@@ -57,7 +57,7 @@ class HashSet[T >: Null <: AnyRef](initialCapacity: int) extends Set[T] {
     var i = 0
     while (i < oldtable.length) {
       val entry = oldtable(i)
-      if (entry != null) addEntry(entry.asInstanceOf[T])
+      if (entry ne null) addEntry(entry.asInstanceOf[T])
       i = i + 1
     }
   }
diff --git a/src/compiler/scala/tools/nsc/util/NameTransformer.scala b/src/compiler/scala/tools/nsc/util/NameTransformer.scala
index 54c444f118..23ed83eb54 100644
--- a/src/compiler/scala/tools/nsc/util/NameTransformer.scala
+++ b/src/compiler/scala/tools/nsc/util/NameTransformer.scala
@@ -53,18 +53,18 @@ object NameTransformer {
     var i = 0
     while (i < len) {
       val c = name charAt i
-      if (c < nops && op2code(c) != null) {
-        if (buf == null) {
+      if (c < nops && (op2code(c) ne null)) {
+        if (buf eq null) {
           buf = new StringBuilder()
           buf.append(name.substring(0, i))
         }
         buf.append(op2code(c))
-      } else if (buf != null) {
+      } else if (buf ne null) {
         buf.append(c)
       }
       i = i + 1
     }
-    if (buf == null) name else buf.toString()
+    if (buf eq null) name else buf.toString()
   }
 
   /** Replace <code>$op_name</code> by corresponding operator symbol.
@@ -88,9 +88,9 @@ object NameTransformer {
           val ch2 = name.charAt(i+2)
           if ('a' <= ch2 && ch2 <= 'z') {
             ops = code2op((ch1 - 'a') * 26 + ch2 - 'a')
-            while (ops != null && !name.startsWith(ops.code, i)) ops = ops.next;
-            if (ops != null) {
-              if (buf == null) {
+            while ((ops ne null) && !name.startsWith(ops.code, i)) ops = ops.next;
+            if (ops ne null) {
+              if (buf eq null) {
                 buf = new StringBuilder()
                 buf.append(name.substring(0, i))
               }
@@ -100,12 +100,12 @@ object NameTransformer {
           }
         }
       }
-      if (ops == null) {
-        if (buf != null) buf.append(c)
+      if (ops eq null) {
+        if (buf ne null) buf.append(c)
         i = i + 1
       }
     }
     //System.out.println("= " + (if (buf == null) name else buf.toString()));//DEBUG
-    if (buf == null) name else buf.toString()
+    if (buf eq null) name else buf.toString()
   }
 }
diff --git a/src/compiler/scala/tools/nsc/util/Position.scala b/src/compiler/scala/tools/nsc/util/Position.scala
index a7bd8f211e..70988b771c 100644
--- a/src/compiler/scala/tools/nsc/util/Position.scala
+++ b/src/compiler/scala/tools/nsc/util/Position.scala
@@ -80,7 +80,7 @@ class Position( val source : SourceFile, val offset: Int) {
   def inUltimateSource = source.positionInUltimateSource(this)
 
   def dbgString = {
-    "source: " + (if (source == null) source else source . path) + " " +
+    "source: " + (if (source eq null) source else source . path) + " " +
     (if (isLine) "line-" + line
     else if (!hasOffset) "NOP"
     else if (offset >= source.content.length) "out-of-bounds-" + offset else {
@@ -102,7 +102,7 @@ class Position( val source : SourceFile, val offset: Int) {
       return inUltimateSource.toString
 
     val sb = new StringBuilder()
-    if (source != null) {
+    if (source ne null) {
       sb.append(source.file.path)
       if (hasOffset) {
         sb.append(line)
diff --git a/src/compiler/scala/tools/nsc/util/Set.scala b/src/compiler/scala/tools/nsc/util/Set.scala
index 26305972d3..9101841e3f 100644
--- a/src/compiler/scala/tools/nsc/util/Set.scala
+++ b/src/compiler/scala/tools/nsc/util/Set.scala
@@ -17,7 +17,7 @@ abstract class Set[T <: AnyRef] {
   def elements: Iterator[T]
 
   def contains(x: T): boolean =
-    findEntry(x) != null
+    findEntry(x) ne null
 
   def toList = elements.toList
 
diff --git a/src/compiler/scala/tools/nsc/util/TreeSet.scala b/src/compiler/scala/tools/nsc/util/TreeSet.scala
index 5939d914c1..e4dc8f4fd6 100644
--- a/src/compiler/scala/tools/nsc/util/TreeSet.scala
+++ b/src/compiler/scala/tools/nsc/util/TreeSet.scala
@@ -22,7 +22,7 @@ class TreeSet[T >: Null <: AnyRef](less: (T, T) => boolean) extends Set[T] {
 
   def findEntry(x: T): T = {
     def find(t: Tree): T = {
-      if (t == null) null
+      if (t eq null) null
       else if (less(x, t.elem)) find(t.l)
       else if (less(t.elem, x)) find(t.r)
       else t.elem
@@ -32,7 +32,7 @@ class TreeSet[T >: Null <: AnyRef](less: (T, T) => boolean) extends Set[T] {
 
   def addEntry(x: T): unit = {
     def add(t: Tree): Tree = {
-      if (t == null) new Tree(x)
+      if (t eq null) new Tree(x)
       else if (less(x, t.elem)) { t.l = add(t.l); t }
       else if (less(t.elem, x)) { t.r = add(t.r); t }
       else t
@@ -43,14 +43,14 @@ class TreeSet[T >: Null <: AnyRef](less: (T, T) => boolean) extends Set[T] {
   def elements = {
     def elems(t: Tree): Iterator[T] = {
       var it = Iterator.single(t.elem)
-      if (t.l != null) it = elems(t.l) append it
-      if (t.r != null) it = it append elems(t.r)
+      if (t.l ne null) it = elems(t.l) append it
+      if (t.r ne null) it = it append elems(t.r)
       it
     }
-    if (tree == null) Iterator.empty else elems(tree)
+    if (tree eq null) Iterator.empty else elems(tree)
   }
 
   override def toString(): String = {
-    if (tree == null) "<empty>" else "(..." + tree.elem + "...)"
+    if (tree eq null) "<empty>" else "(..." + tree.elem + "...)"
   }
 }
diff --git a/src/library/scala/Application.scala b/src/library/scala/Application.scala
index 9b268abeae..672969e91c 100644
--- a/src/library/scala/Application.scala
+++ b/src/library/scala/Application.scala
@@ -50,7 +50,7 @@ trait Application {
    *  @param args the arguments passed to the main method
    */
   def main(args: Array[String]) = {
-    if (getProperty("scala.time") != null) {
+    if (getProperty("scala.time") ne null) {
       val total = currentTime - executionStart
       Console.println("[total " + total + "ms]")
     }
diff --git a/src/library/scala/BigInt.scala b/src/library/scala/BigInt.scala
index 8efad433b1..9be8a45dbd 100644
--- a/src/library/scala/BigInt.scala
+++ b/src/library/scala/BigInt.scala
@@ -32,7 +32,7 @@ object BigInt {
   def apply(i: Int): BigInt =
     if (minCached <= i && i <= maxCached) {
       var n = cache(i)
-      if (n == null) { n = new BigInt(BigInteger.valueOf(i)); cache(i) = n }
+      if (n eq null) { n = new BigInt(BigInteger.valueOf(i)); cache(i) = n }
       n
     } else new BigInt(BigInteger.valueOf(i))
 
diff --git a/src/library/scala/Console.scala b/src/library/scala/Console.scala
index 8fa4285ab6..7cc8e9d4e9 100644
--- a/src/library/scala/Console.scala
+++ b/src/library/scala/Console.scala
@@ -142,7 +142,7 @@ object Console {
    *  @param obj the object to print.
    */
   def print(obj: Any): Unit =
-    out.print(if (obj == null) "null" else obj.toString())
+    out.print(if (null == obj) "null" else obj.toString())
 
   /** Flush the output stream. This function is required when partial
    *  output (i.e. output not terminated by a new line character) has
@@ -173,7 +173,7 @@ object Console {
   // todo: Uncurry
   def printf(text: String)(args: Any*): Unit =
     out.print(
-      if (text == null) "null"
+      if (text eq null) "null"
       else MessageFormat.format(text, textParams(args))
     )
 
diff --git a/src/library/scala/Enumeration.scala b/src/library/scala/Enumeration.scala
index b92ad6ca4e..cff1c41238 100644
--- a/src/library/scala/Enumeration.scala
+++ b/src/library/scala/Enumeration.scala
@@ -66,7 +66,7 @@ abstract class Enumeration(initial: Int, names: String*) {
   private var vcache: List[Value] = null
 
   private def updateCache: List[Value] =
-    if (vcache == null) {
+    if (vcache eq null) {
       vcache = values.values.toList.sort((p1, p2) => p1.id < p2.id);
       vcache
     } else
@@ -132,7 +132,7 @@ abstract class Enumeration(initial: Int, names: String*) {
       topId = nextId
     def id = i
     override def toString() =
-      if (name == null) Enumeration.this.name + "(" + i + ")"
+      if (name eq null) Enumeration.this.name + "(" + i + ")"
       else name
   }
 }
diff --git a/src/library/scala/MatchError.scala b/src/library/scala/MatchError.scala
index 6ef969b97c..57ada9efbd 100644
--- a/src/library/scala/MatchError.scala
+++ b/src/library/scala/MatchError.scala
@@ -24,7 +24,7 @@ import Predef._
 object MatchError {
 
   def string(obj: Any) =
-    if(obj != null) obj.toString() else "null"
+    if (null != obj) obj.toString() else "null"
 
   // todo: change pattern matcher so that dummy type parameter T can be removed.
   def fail[T](source: String, line: Int): Nothing =
diff --git a/src/library/scala/collection/mutable/DoubleLinkedList.scala b/src/library/scala/collection/mutable/DoubleLinkedList.scala
index f2916d39e9..5ed7a5dbb8 100644
--- a/src/library/scala/collection/mutable/DoubleLinkedList.scala
+++ b/src/library/scala/collection/mutable/DoubleLinkedList.scala
@@ -28,24 +28,24 @@ abstract class DoubleLinkedList[A, This >: Null <: DoubleLinkedList[A, This]]
   var prev: This
 
   override def append(that: This): Unit =
-    if (that == null)
+    if (that eq null)
       ()
-    else if (next == null) {
+    else if (next eq null) {
       next = that
       that.prev = this
     } else
       next.append(that)
 
-  override def insert(that: This): Unit = if (that != null) {
+  override def insert(that: This): Unit = if (that ne null) {
     that.append(next)
     next = that
     that.prev = this
   }
 
   def remove: Unit = {
-    if (next != null)
+    if (next ne null)
       next.prev = prev
-    if (prev != null)
+    if (prev ne null)
       prev.next = next
     prev = null
     next = null
diff --git a/src/library/scala/collection/mutable/ListBuffer.scala b/src/library/scala/collection/mutable/ListBuffer.scala
index 5ec6e6eb7c..1c248835e9 100644
--- a/src/library/scala/collection/mutable/ListBuffer.scala
+++ b/src/library/scala/collection/mutable/ListBuffer.scala
@@ -248,7 +248,7 @@ final class ListBuffer[A] extends Buffer[A] {
       if (!hasNext) {
         throw new NoSuchElementException("next on empty Iterator")
       } else {
-        if (cursor == null) cursor = start else cursor = cursor.tail
+        if (cursor eq null) cursor = start else cursor = cursor.tail
         cursor.head
       }
   }
diff --git a/src/library/scala/collection/mutable/MutableList.scala b/src/library/scala/collection/mutable/MutableList.scala
index 6e57074641..8983949aaa 100644
--- a/src/library/scala/collection/mutable/MutableList.scala
+++ b/src/library/scala/collection/mutable/MutableList.scala
@@ -69,12 +69,12 @@ trait MutableList[A] extends Seq[A] with PartialFunction[Int, A] {
   /** Returns an iterator over all elements of this list.
    */
   def elements: Iterator[A] =
-    if (first == null) Nil.elements else first.elements
+    if (first eq null) Nil.elements else first.elements
 
   /** Returns an instance of <code>scala.List</code> containing the same
    *  sequence of elements.
    */
-  override def toList: List[A] = if (first == null) Nil else first.toList
+  override def toList: List[A] = if (first eq null) Nil else first.toList
 
   override protected def stringPrefix: String = "MutableList"
 }
diff --git a/src/library/scala/collection/mutable/Queue.scala b/src/library/scala/collection/mutable/Queue.scala
index 7d31b2b66e..271c8d680d 100644
--- a/src/library/scala/collection/mutable/Queue.scala
+++ b/src/library/scala/collection/mutable/Queue.scala
@@ -27,7 +27,7 @@ class Queue[A] extends MutableList[A] {
    *
    *  @return true, iff there is no element in the queue.
    */
-  override def isEmpty: Boolean = (first == null)
+  override def isEmpty: Boolean = (first eq null)
 
   /** Inserts a single element at the end of the queue.
    *
@@ -64,12 +64,12 @@ class Queue[A] extends MutableList[A] {
    *  @return the first element of the queue.
    */
   def dequeue: A =
-    if (first == null)
+    if (first eq null)
       throw new NoSuchElementException("queue empty")
     else {
       val res = first.elem
       first = first.next
-      if (first == null) last = null
+      if (first eq null) last = null
       len = len - 1
       res
     }
@@ -81,15 +81,15 @@ class Queue[A] extends MutableList[A] {
    *  @return the first element of the queue for which p yields true
    */
   def dequeueFirst(p: A => Boolean): Option[A] =
-    if (first == null)
+    if (first eq null)
       None
     else if (p(first.elem)) {
       val res: Option[A] = Some(first.elem)
       first = first.next
       len = len - 1
-      if (first == null) {
+      if (first eq null) {
         last = null
-      } else if (first.next == null) {
+      } else if (first.next eq null) {
         last = first
       }
       res
@@ -108,16 +108,16 @@ class Queue[A] extends MutableList[A] {
    */
   def dequeueAll(p: A => Boolean): Seq[A] = {
     val res = new ArrayBuffer[A]
-    if (first == null)
+    if (first eq null)
       res
     else {
       while (p(first.elem)) {
         res += first.elem
         first = first.next
         len = len - 1
-        if (first == null) {
+        if (first eq null) {
           last = null
-        } else if (first.next == null) {
+        } else if (first.next eq null) {
           last = first
         }
       }
@@ -132,15 +132,15 @@ class Queue[A] extends MutableList[A] {
 
   private def extractFirst(start: LinkedList[A], p: A => Boolean): Option[LinkedList[A]] = {
     var cell = start
-    while ((cell.next != null) && !p(cell.next.elem)) {
+    while ((cell.next ne null) && !p(cell.next.elem)) {
       cell = cell.next
     }
-    if (cell.next == null)
+    if (cell.next eq null)
       None
     else {
       val res: Option[LinkedList[A]] = Some(cell.next)
       cell.next = cell.next.next
-      if (cell.next == null)
+      if (cell.next eq null)
         last = cell
       len = len - 1
       res
diff --git a/src/library/scala/collection/mutable/SingleLinkedList.scala b/src/library/scala/collection/mutable/SingleLinkedList.scala
index 6a889fc49e..2fc51ad9a2 100644
--- a/src/library/scala/collection/mutable/SingleLinkedList.scala
+++ b/src/library/scala/collection/mutable/SingleLinkedList.scala
@@ -28,29 +28,29 @@ abstract class SingleLinkedList[A, This >: Null <: SingleLinkedList[A, This]]
 
   var next: This
 
-  def length: Int = 1 + (if (next == null) 0 else next.length)
+  def length: Int = 1 + (if (next eq null) 0 else next.length)
 
   def append(that: This): Unit =
-    if (next == null) next = that else next.append(that)
+    if (next eq null) next = that else next.append(that)
 
-  def insert(that: This): Unit = if (that != null) {
+  def insert(that: This): Unit = if (that ne null) {
     that.append(next)
     next = that
   }
 
   def apply(n: Int): A =
     if (n == 0) elem
-    else if (next == null) throw new IndexOutOfBoundsException("unknown element")
+    else if (next eq null) throw new IndexOutOfBoundsException("unknown element")
     else next.apply(n - 1)
 
   def get(n: Int): Option[A] =
     if (n == 0) Some(elem)
-    else if (next == null) None
+    else if (next eq null) None
     else next.get(n - 1)
 
   def elements: Iterator[A] = new Iterator[A] {
     var elems = SingleLinkedList.this
-    def hasNext = (elems != null)
+    def hasNext = (elems ne null)
     def next = {
       val res = elems.elem
       elems = elems.next
diff --git a/src/library/scala/collection/mutable/Stack.scala b/src/library/scala/collection/mutable/Stack.scala
index 825e87c629..e3aa316c21 100644
--- a/src/library/scala/collection/mutable/Stack.scala
+++ b/src/library/scala/collection/mutable/Stack.scala
@@ -25,7 +25,7 @@ class Stack[A] extends MutableList[A] {
    *
    *  @return true, iff there is no element on the stack
    */
-  override def isEmpty: Boolean = (first == null)
+  override def isEmpty: Boolean = (first eq null)
 
   /** Pushes a single element on top of the stack.
    *
@@ -63,7 +63,7 @@ class Stack[A] extends MutableList[A] {
    *  @throws Predef.NoSuchElementException
    *  @return the top element
    */
-  def top: A = if (first == null) throw new NoSuchElementException("stack empty") else first.elem
+  def top: A = if (first eq null) throw new NoSuchElementException("stack empty") else first.elem
 
   /** Removes the top element from the stack.
    *
@@ -71,7 +71,7 @@ class Stack[A] extends MutableList[A] {
    *  @return the top element
    */
   def pop: A =
-    if (first != null) {
+    if (first ne null) {
       val res = first.elem
       first = first.next
       len = len - 1;
diff --git a/src/library/scala/concurrent/Actor.scala b/src/library/scala/concurrent/Actor.scala
index 8f2534bb95..15b77bf3fd 100644
--- a/src/library/scala/concurrent/Actor.scala
+++ b/src/library/scala/concurrent/Actor.scala
@@ -37,7 +37,7 @@ abstract class Actor extends Thread {
   private var pid: Pid = null
 
   def self = {
-    if (pid == null) pid = new Pid(this)
+    if (pid eq null) pid = new Pid(this)
     pid
   }
 
diff --git a/src/library/scala/concurrent/Channel.scala b/src/library/scala/concurrent/Channel.scala
index f7a156271f..bab6345ab9 100644
--- a/src/library/scala/concurrent/Channel.scala
+++ b/src/library/scala/concurrent/Channel.scala
@@ -36,7 +36,7 @@ class Channel[a] {
   }
 
   def read: a = synchronized {
-    if (written.next == null) {
+    if (null == written.next) {
       nreaders = nreaders + 1; wait(); nreaders = nreaders - 1
     }
     val x = written.elem
diff --git a/src/library/scala/concurrent/MailBox.scala b/src/library/scala/concurrent/MailBox.scala
index 7a8b4eac20..e1399e9e58 100644
--- a/src/library/scala/concurrent/MailBox.scala
+++ b/src/library/scala/concurrent/MailBox.scala
@@ -31,13 +31,13 @@ class MailBox extends AnyRef with ListQueueCreator {
     def isDefinedAt(msg: Message) = receiver.isDefinedAt(msg)
 
     def receive(): a = synchronized {
-      while (msg == null) wait()
+      while (msg eq null) wait()
       receiver(msg)
     }
 
     def receiveWithin(msec: long): a = synchronized {
-      if (msg == null) wait(msec)
-      receiver(if (msg != null) msg else TIMEOUT)
+      if (msg eq null) wait(msec)
+      receiver(if (msg ne null) msg else TIMEOUT)
     }
   }
 
@@ -157,13 +157,13 @@ trait LinkedListQueueCreator {
     def extractFirst(l: t, p: a => boolean): Option[Pair[a, t]] = {
       var xs = l._1
       var xs1 = xs.next
-      while (xs1 != null && !p(xs1.elem)) {
+      while ((xs1 ne null) && !p(xs1.elem)) {
         xs = xs1
         xs1 = xs1.next
       }
-      if (xs1 != null) {
+      if (xs1 ne null) {
         xs.next = xs1.next
-        if (xs.next == null)
+        if (xs.next eq null)
           Some(Pair(xs1.elem, Pair(l._1, xs)))
         else
           Some(Pair(xs1.elem, l))
diff --git a/src/library/scala/mobile/Code.scala b/src/library/scala/mobile/Code.scala
index e7166bfc1a..33ddc8f6fa 100644
--- a/src/library/scala/mobile/Code.scala
+++ b/src/library/scala/mobile/Code.scala
@@ -185,7 +185,7 @@ class Code(clazz: java.lang.Class) {
       val method = clazz.getMethod(methName, argTypes)
       var obj: JObject = null
       if (! Modifier.isStatic(method.getModifiers())) {
-        if (instance == null) {
+        if (instance eq null) {
           instance = try {
             clazz.newInstance()
           } catch { case _ =>
@@ -202,7 +202,7 @@ class Code(clazz: java.lang.Class) {
         obj = instance
       }
       val result = method.invoke(obj, args)
-      if (result == null) ().asInstanceOf[JObject] else result
+      if (result eq null) ().asInstanceOf[JObject] else result
     }
     catch {
       case me: NoSuchMethodException =>
diff --git a/src/library/scala/mobile/Location.scala b/src/library/scala/mobile/Location.scala
index 246db26fc9..2b8d456ea5 100644
--- a/src/library/scala/mobile/Location.scala
+++ b/src/library/scala/mobile/Location.scala
@@ -41,7 +41,7 @@ class Location(url: URL) {
 
   /** The class loader associated with this location.
    */
-  private val loader = if (url == null)
+  private val loader = if (url eq null)
     ClassLoader.getSystemClassLoader()
   else
     lcache.get(url) match {
diff --git a/src/library/scala/runtime/BoxedAnyArray.scala b/src/library/scala/runtime/BoxedAnyArray.scala
index 558c01dead..7242e5763a 100644
--- a/src/library/scala/runtime/BoxedAnyArray.scala
+++ b/src/library/scala/runtime/BoxedAnyArray.scala
@@ -28,7 +28,7 @@ final class BoxedAnyArray(val length: Int) extends BoxedArray {
   private var elemClass: Class = null
 
   def apply(index: Int): AnyRef = synchronized {
-    if (unboxed == null)
+    if (unboxed eq null)
       boxed(index);
     else if (elemClass eq ScalaRunTime.IntTYPE)
       Int.box(unboxed.asInstanceOf[Array[Int]](index))
@@ -51,7 +51,7 @@ final class BoxedAnyArray(val length: Int) extends BoxedArray {
   }
 
   def update(index: Int, elem: AnyRef): Unit = synchronized {
-    if (unboxed == null)
+    if (unboxed eq null)
       boxed(index) = elem
     else if (elemClass eq ScalaRunTime.IntTYPE)
       unboxed.asInstanceOf[Array[Int]](index) = Int.unbox(elem)
@@ -85,7 +85,7 @@ final class BoxedAnyArray(val length: Int) extends BoxedArray {
     else unbox(Platform.getClassForName(elemTag))
 
   def unbox(elemClass: Class): AnyRef = synchronized {
-    if (unboxed == null) {
+    if (unboxed eq null) {
       this.elemClass = elemClass;
       if (elemClass eq ScalaRunTime.IntTYPE) {
 	val newvalue = new Array[Int](length)
@@ -165,21 +165,21 @@ final class BoxedAnyArray(val length: Int) extends BoxedArray {
 
   override def equals(other: Any): Boolean = (
     other.isInstanceOf[BoxedAnyArray] && (this eq (other.asInstanceOf[BoxedAnyArray])) ||
-    (if (unboxed == null) boxed == other else unboxed == other)
+    (if (unboxed eq null) boxed == other else unboxed == other)
   )
 
   override def hashCode(): Int = hash
 
   def value: AnyRef = {
-    if (unboxed == null) throw new NotDefinedError("BoxedAnyArray.value")
+    if (unboxed eq null) throw new NotDefinedError("BoxedAnyArray.value")
     unboxed
   }
 
   private def adapt(other: AnyRef): AnyRef =
-    if (this.unboxed == null)
+    if (this.unboxed eq null)
       other match {
         case that: BoxedAnyArray =>
-          if (that.unboxed == null) {
+          if (that.unboxed eq null) {
             that.boxed
           } else {
             if (ScalaRunTime.isValueClass(that.elemClass)) unbox(that.elemClass);
@@ -209,7 +209,7 @@ final class BoxedAnyArray(val length: Int) extends BoxedArray {
     else
       other match {
         case that: BoxedAnyArray =>
-          if (that.unboxed != null) that.unboxed
+          if (that.unboxed ne null) that.unboxed
           else if (ScalaRunTime.isValueClass(this.elemClass)) that.unbox(this.elemClass)
           else that.boxed
         case that: BoxedArray =>
@@ -220,12 +220,12 @@ final class BoxedAnyArray(val length: Int) extends BoxedArray {
 
   override def copyFrom(src: AnyRef, from: Int, to: Int, len: Int): Unit = {
     val src1 = adapt(src)
-    Array.copy(src1, from, if (unboxed != null) unboxed else boxed, to, len)
+    Array.copy(src1, from, if (unboxed ne null) unboxed else boxed, to, len)
   }
 
   override def copyTo(from: Int, dest: AnyRef, to: Int, len: Int): Unit = {
     var dest1 = adapt(dest)
-    Array.copy(if (unboxed != null) unboxed else boxed, from, dest1, to, len)
+    Array.copy(if (unboxed ne null) unboxed else boxed, from, dest1, to, len)
   }
 
   override def subArray(start: Int, end: Int): AnyRef = {
diff --git a/src/library/scala/runtime/ScalaRunTime.scala b/src/library/scala/runtime/ScalaRunTime.scala
index 7173253316..f0b5eb3ddc 100644
--- a/src/library/scala/runtime/ScalaRunTime.scala
+++ b/src/library/scala/runtime/ScalaRunTime.scala
@@ -52,7 +52,7 @@ object ScalaRunTime {
     def run(): Unit = result = block;
 
     def Catch[b >: a](handler: PartialFunction[Throwable, b]): b =
-      if (exception == null)
+      if (exception eq null)
 	result.asInstanceOf[b]
       // !!! else if (exception is LocalReturn)
       // !!!   // ...
@@ -62,7 +62,7 @@ object ScalaRunTime {
 	throw exception;
 
     def Finally(handler: Unit): a =
-      if (exception == null)
+      if (exception eq null)
         result.asInstanceOf[a]
       else
         throw exception;
diff --git a/src/library/scala/xml/Elem.scala b/src/library/scala/xml/Elem.scala
index 96b571c505..77941f1c60 100644
--- a/src/library/scala/xml/Elem.scala
+++ b/src/library/scala/xml/Elem.scala
@@ -28,7 +28,7 @@ case class Elem(override val prefix: String,
                 override val scope: NamespaceBinding,
                 val child: Node*) extends Node {
 
-  if (prefix != null && 0 == prefix.length())
+  if ((null != prefix) && 0 == prefix.length())
     throw new IllegalArgumentException("prefix of zero length, use null instead");
 
   if (null == scope)
diff --git a/src/library/scala/xml/NamespaceBinding.scala b/src/library/scala/xml/NamespaceBinding.scala
index 0a3f860803..c1acb444e5 100644
--- a/src/library/scala/xml/NamespaceBinding.scala
+++ b/src/library/scala/xml/NamespaceBinding.scala
@@ -59,7 +59,7 @@ class NamespaceBinding(val prefix: String,
   def toString(sb: StringBuilder, stop: NamespaceBinding): Unit = {
     if (this ne stop) { // contains?
       sb.append(" xmlns")
-      if (prefix != null) {
+      if (prefix ne null) {
         sb.append(':').append(prefix)
       }
       sb.append('=')
diff --git a/src/library/scala/xml/Node.scala b/src/library/scala/xml/Node.scala
index 141a9f9f1b..e9d233af13 100644
--- a/src/library/scala/xml/Node.scala
+++ b/src/library/scala/xml/Node.scala
@@ -67,7 +67,7 @@ abstract class Node extends NodeSeq {
    * @return    the namespace if <code>scope != null</code> and prefix was
    *            found, else <code>null</code>
    */
-  def getNamespace(pre: String) = if (scope == null) null else scope.getURI(pre)
+  def getNamespace(pre: String) = if (scope eq null) null else scope.getURI(pre)
 
   /**
    * Convenience method, looks up an unprefixed attribute in attributes of this node.
diff --git a/src/library/scala/xml/PrefixedAttribute.scala b/src/library/scala/xml/PrefixedAttribute.scala
index 96ba45c73c..397a68507c 100644
--- a/src/library/scala/xml/PrefixedAttribute.scala
+++ b/src/library/scala/xml/PrefixedAttribute.scala
@@ -21,7 +21,7 @@ class PrefixedAttribute(val pre: String,
                         val value: Seq[Node],
                         val next: MetaData) extends MetaData {
 
-  if(value == null)
+  if(value eq null)
     throw new UnsupportedOperationException("value is null")
 
   /** same as this(key, Utility.parseAttributeValue(value), next) */
@@ -71,7 +71,7 @@ class PrefixedAttribute(val pre: String,
 
 
   /** appends string representation of only this attribute to stringbuffer */
-  def toString1(sb:StringBuilder): Unit = if(value!=null) {
+  def toString1(sb:StringBuilder): Unit = if(value ne null) {
     sb.append(pre)
     sb.append(':')
     sb.append(key)
diff --git a/src/library/scala/xml/UnprefixedAttribute.scala b/src/library/scala/xml/UnprefixedAttribute.scala
index 5159c5a67f..8f08da3696 100644
--- a/src/library/scala/xml/UnprefixedAttribute.scala
+++ b/src/library/scala/xml/UnprefixedAttribute.scala
@@ -18,11 +18,11 @@ import compat.StringBuilder
  */
 class UnprefixedAttribute(val key: String, val value: Seq[Node], next1: MetaData) extends MetaData {
 
-  val next = if(value != null) next1 else next1.remove(key)
+  val next = if(value ne null) next1 else next1.remove(key)
 
   /** same as this(key, Utility.parseAttributeValue(value), next) */
   def this(key: String, value: String, next: MetaData) =
-    this(key, if(value!=null) Text(value) else {val z:NodeSeq=null;z}, next)
+    this(key, if(value ne null) Text(value) else {val z:NodeSeq=null;z}, next)
 
   /** returns a copy of this unprefixed attribute with the given next field*/
   def copy(next: MetaData) =
@@ -58,13 +58,13 @@ class UnprefixedAttribute(val key: String, val value: Seq[Node], next1: MetaData
   /** returns the hashcode.
    */
   override def hashCode() =
-    key.hashCode() * 7 + { if(value!=null) value.hashCode() * 53 else 0 } + next.hashCode()
+    key.hashCode() * 7 + { if(value ne null) value.hashCode() * 53 else 0 } + next.hashCode()
 
   /** returns false */
   final def isPrefixed = false
 
   /** appends string representation of only this attribute to stringbuffer */
-  def toString1(sb:StringBuilder): Unit = if(value!=null) {
+  def toString1(sb:StringBuilder): Unit = if(value ne null) {
     sb.append(key)
     sb.append('=')
     val sb2 = new StringBuilder()
diff --git a/src/library/scala/xml/Utility.scala b/src/library/scala/xml/Utility.scala
index fdc6681b5c..2788fd9529 100644
--- a/src/library/scala/xml/Utility.scala
+++ b/src/library/scala/xml/Utility.scala
@@ -159,7 +159,7 @@ object Utility extends AnyRef with parsing.TokenTests {
         // print tag with namespace declarations
         sb.append('<')
         x.nameToString(sb)
-        if (x.attributes != null) {
+        if (x.attributes ne null) {
           x.attributes.toString(sb)
         }
         x.scope.toString(sb, pscope)
@@ -215,7 +215,7 @@ object Utility extends AnyRef with parsing.TokenTests {
    * @param children
    */
   def hashCode(pre: String, label: String, attribHashCode: Int, scpeHash: Int, children: Seq[Node]) = {
-    ( if(pre!=null) {41 * pre.hashCode() % 7} else {0})
+    ( if(pre ne null) {41 * pre.hashCode() % 7} else {0})
     + label.hashCode() * 53
     + attribHashCode * 7
     + scpeHash * 31
@@ -337,7 +337,7 @@ object Utility extends AnyRef with parsing.TokenTests {
           return "< not allowed in attribute value";
         case '&' =>
           val n = getName(value, i+1);
-          if (n == null)
+          if (n eq null)
             return "malformed entity reference in attribute value ["+value+"]";
           i = i + n.length() + 1
           if (i >= value.length() || value.charAt(i) != ';')
@@ -372,7 +372,7 @@ object Utility extends AnyRef with parsing.TokenTests {
               sb.append(theChar)
 
             case x =>
-              if (rfb==null) rfb = new StringBuilder()
+              if (rfb eq null) rfb = new StringBuilder()
               rfb.append(x)
               c = it.next
               while (c != ';') {
diff --git a/src/library/scala/xml/XML.scala b/src/library/scala/xml/XML.scala
index 673c44d333..e9e51ca520 100644
--- a/src/library/scala/xml/XML.scala
+++ b/src/library/scala/xml/XML.scala
@@ -151,7 +151,7 @@ object XML  {
   final def write(w: java.io.Writer, node: Node, enc: String, xmlDecl: Boolean, doctype: dtd.DocType): Unit = {
     /* TODO: optimize by giving writer parameter to toXML*/
     if (xmlDecl) w.write("<?xml version='1.0' encoding='" + enc + "'?>\n")
-    if (doctype != null) w.write( doctype.toString() + "\n")
+    if (doctype ne null) w.write( doctype.toString() + "\n")
     w.write(Utility.toXML(node))
   }
 }
diff --git a/src/library/scala/xml/dtd/ElementValidator.scala b/src/library/scala/xml/dtd/ElementValidator.scala
index 19406c577d..645caa66eb 100644
--- a/src/library/scala/xml/dtd/ElementValidator.scala
+++ b/src/library/scala/xml/dtd/ElementValidator.scala
@@ -57,7 +57,7 @@ class ElementValidator() extends Function1[Node,Boolean] {
 
             }
             case _ =>
-              x.namespace == null
+              x.namespace eq null
           }}
           . map { x => ElemName(x.label) }
           . elements;
diff --git a/src/library/scala/xml/dtd/ExternalID.scala b/src/library/scala/xml/dtd/ExternalID.scala
index 304c8b01e0..514db9c60f 100644
--- a/src/library/scala/xml/dtd/ExternalID.scala
+++ b/src/library/scala/xml/dtd/ExternalID.scala
@@ -66,7 +66,7 @@ case class PublicID( publicId:String, systemId:String ) extends ExternalID with
     throw new IllegalArgumentException(
       "publicId must consist of PubidChars"
     )
-  if( systemId != null && !checkSysID( systemId ) )
+  if( (systemId ne null) && !checkSysID( systemId ) )
     throw new IllegalArgumentException(
       "can't use both \" and ' in systemId"
     )
@@ -83,7 +83,7 @@ case class PublicID( publicId:String, systemId:String ) extends ExternalID with
   /** appends "PUBLIC "+publicId+" SYSTEM "+systemId to argument */
   override def toString(sb: StringBuilder): StringBuilder = {
     Utility.publicLiteralToString( sb, publicId ).append(' ')
-    if(systemId!=null)
+    if(systemId ne null)
       Utility.systemLiteralToString( sb, systemId )
     else
       sb
diff --git a/src/library/scala/xml/parsing/ExternalSources.scala b/src/library/scala/xml/parsing/ExternalSources.scala
index d3fd41314d..90b7f406a4 100644
--- a/src/library/scala/xml/parsing/ExternalSources.scala
+++ b/src/library/scala/xml/parsing/ExternalSources.scala
@@ -30,7 +30,7 @@ trait ExternalSources requires (ExternalSources with MarkupParser with MarkupHan
     var inputLine:String = null;
 
     //while (inputLine = in.readLine()) != null) {
-    while ({inputLine = in.readLine(); inputLine} != null) {
+    while ({inputLine = in.readLine(); inputLine} ne null) {
       // Console.println(inputLine); // DEBUG
       str.append(inputLine);
       str.append('\n'); // readable output
diff --git a/src/library/scala/xml/parsing/FactoryAdapter.scala b/src/library/scala/xml/parsing/FactoryAdapter.scala
index 99d81aef72..d1deabb5a2 100644
--- a/src/library/scala/xml/parsing/FactoryAdapter.scala
+++ b/src/library/scala/xml/parsing/FactoryAdapter.scala
@@ -188,7 +188,7 @@ abstract class FactoryAdapter extends DefaultHandler() {
     // reverse order to get it right
     var v: List[Node] = Nil
     var child: Node = hStack.pop
-    while (child != null) {
+    while (child ne null) {
       v = child::v
       child = hStack.pop
     }
@@ -209,7 +209,7 @@ abstract class FactoryAdapter extends DefaultHandler() {
     curTag = tagStack.pop
 
     capture =
-      if (curTag != null) nodeContainsText(curTag) // root level
+      if (curTag ne null) nodeContainsText(curTag) // root level
       else false
   } // endElement(String,String,String)
 
@@ -243,7 +243,7 @@ abstract class FactoryAdapter extends DefaultHandler() {
     Console.print("] ")
 
     var systemId = ex.getSystemId()
-    if (systemId != null) {
+    if (systemId ne null) {
       val index = systemId.lastIndexOf('/'.asInstanceOf[Int])
       if (index != -1)
         systemId = systemId.substring(index + 1)
diff --git a/src/library/scala/xml/parsing/MarkupParser.scala b/src/library/scala/xml/parsing/MarkupParser.scala
index c3a69b555a..e1813fdac5 100644
--- a/src/library/scala/xml/parsing/MarkupParser.scala
+++ b/src/library/scala/xml/parsing/MarkupParser.scala
@@ -580,7 +580,7 @@ trait MarkupParser requires (MarkupParser with MarkupHandler) extends AnyRef wit
   def parseDTD(): Unit = { // dirty but fast
     //Console.println("(DEBUG) parseDTD");
     var extID: ExternalID = null
-    if (this.dtd != null)
+    if (this.dtd ne null)
       reportSyntaxError("unexpected character (DOCTYPE already defined");
     xToken("DOCTYPE")
     xSpace
@@ -649,7 +649,7 @@ trait MarkupParser requires (MarkupParser with MarkupHandler) extends AnyRef wit
       /*override val */decls      = handle.decls.reverse
     }
     //this.dtd.initializeEntities();
-    if (doc!=null)
+    if (doc ne null)
       doc.dtd = this.dtd
 
     handle.endDTD(n)
diff --git a/src/library/scala/xml/pull/XMLEventReader.scala b/src/library/scala/xml/pull/XMLEventReader.scala
index b89bdb764d..130d7afe19 100644
--- a/src/library/scala/xml/pull/XMLEventReader.scala
+++ b/src/library/scala/xml/pull/XMLEventReader.scala
@@ -59,7 +59,7 @@ class XMLEventReader extends Iterator[XMLEvent] {
     notifyAll
   }
   def getAndClearEvent: XMLEvent = synchronized {
-    while(xmlEvent == null) {
+    while(xmlEvent eq null) {
       wait()
     }
     val r = xmlEvent