Merge remote-tracking branch 'upstream/2.12.x' into opt/heuristics

72 files changed, 577 insertions, 668 deletions

diff --git a/src/compiler/scala/reflect/reify/phases/Reshape.scala b/src/compiler/scala/reflect/reify/phases/Reshape.scala
index 6c073c0b4c..091d42bb6d 100644
--- a/src/compiler/scala/reflect/reify/phases/Reshape.scala
+++ b/src/compiler/scala/reflect/reify/phases/Reshape.scala
@@ -325,8 +325,7 @@ trait Reshape {
           if (reifyDebug) println(s"reconstructed lazy val is $vdef1")
           vdef1::Nil
         case ddef: DefDef if ddef.symbol.isLazy =>
-          def hasUnitType(sym: Symbol) = (sym.tpe.typeSymbol == UnitClass) && sym.tpe.annotations.isEmpty
-          if (hasUnitType(ddef.symbol)) {
+          if (isUnitType(ddef.symbol.info)) {
             // since lazy values of type Unit don't have val's
             // we need to create them from scratch
             toPreTyperLazyVal(ddef) :: Nil
diff --git a/src/compiler/scala/tools/nsc/ScriptRunner.scala b/src/compiler/scala/tools/nsc/ScriptRunner.scala
index 6d24b31531..bf93ad30bc 100644
--- a/src/compiler/scala/tools/nsc/ScriptRunner.scala
+++ b/src/compiler/scala/tools/nsc/ScriptRunner.scala
@@ -16,16 +16,16 @@ import util.Exceptional.unwrap
 
 /** An object that runs Scala code in script files.
  *
- *  <p>For example, here is a complete Scala script on Unix:</pre>
- *  <pre>
+ *  For example, here is a complete Scala script on Unix:
+ *  {{{
  *    #!/bin/sh
  *    exec scala "$0" "$@"
  *    !#
  *    Console.println("Hello, world!")
  *    args.toList foreach Console.println
- *  </pre>
- *  <p>And here is a batch file example on Windows XP:</p>
- *  <pre>
+ *  }}}
+ *  And here is a batch file example on Windows XP:
+ *  {{{
  *    ::#!
  *    @echo off
  *    call scala %0 %*
@@ -33,7 +33,7 @@ import util.Exceptional.unwrap
  *    ::!#
  *    Console.println("Hello, world!")
  *    args.toList foreach Console.println
- *  </pre>
+ *  }}}
  *
  *  @author  Lex Spoon
  *  @version 1.0, 15/05/2006
diff --git a/src/compiler/scala/tools/nsc/ast/TreeGen.scala b/src/compiler/scala/tools/nsc/ast/TreeGen.scala
index bf53c47e9a..332acf4a26 100644
--- a/src/compiler/scala/tools/nsc/ast/TreeGen.scala
+++ b/src/compiler/scala/tools/nsc/ast/TreeGen.scala
@@ -261,7 +261,7 @@ abstract class TreeGen extends scala.reflect.internal.TreeGen with TreeDSL {
    * Create a method based on a Function
    *
    * Used both to under `-Ydelambdafy:method` create a lifted function and
-   * under `-Ydelamdafy:inline` to create the apply method on the anonymous
+   * under `-Ydelambdafy:inline` to create the apply method on the anonymous
    * class.
    *
    * It creates a method definition with value params cloned from the
diff --git a/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala b/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
index b76fb3d823..f9e6a12241 100644
--- a/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
+++ b/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
@@ -2043,11 +2043,11 @@ self =>
     /** Drop `private` modifier when followed by a qualifier.
      *  Contract `abstract` and `override` to ABSOVERRIDE
      */
-    private def normalizeModifers(mods: Modifiers): Modifiers =
+    private def normalizeModifiers(mods: Modifiers): Modifiers =
       if (mods.isPrivate && mods.hasAccessBoundary)
-        normalizeModifers(mods &~ Flags.PRIVATE)
+        normalizeModifiers(mods &~ Flags.PRIVATE)
       else if (mods hasAllFlags (Flags.ABSTRACT | Flags.OVERRIDE))
-        normalizeModifers(mods &~ (Flags.ABSTRACT | Flags.OVERRIDE) | Flags.ABSOVERRIDE)
+        normalizeModifiers(mods &~ (Flags.ABSTRACT | Flags.OVERRIDE) | Flags.ABSOVERRIDE)
       else
         mods
 
@@ -2092,7 +2092,7 @@ self =>
      *  AccessModifier ::= (private | protected) [AccessQualifier]
      *  }}}
      */
-    def accessModifierOpt(): Modifiers = normalizeModifers {
+    def accessModifierOpt(): Modifiers = normalizeModifiers {
       in.token match {
         case m @ (PRIVATE | PROTECTED)  => in.nextToken() ; accessQualifierOpt(Modifiers(flagTokens(m)))
         case _                          => NoMods
@@ -2106,7 +2106,7 @@ self =>
      *              |  override
      *  }}}
      */
-    def modifiers(): Modifiers = normalizeModifers {
+    def modifiers(): Modifiers = normalizeModifiers {
       def loop(mods: Modifiers): Modifiers = in.token match {
         case PRIVATE | PROTECTED =>
           loop(accessQualifierOpt(addMod(mods, flagTokens(in.token), tokenRange(in))))
diff --git a/src/compiler/scala/tools/nsc/ast/parser/Scanners.scala b/src/compiler/scala/tools/nsc/ast/parser/Scanners.scala
index 92833d647b..51bb0d3c5b 100644
--- a/src/compiler/scala/tools/nsc/ast/parser/Scanners.scala
+++ b/src/compiler/scala/tools/nsc/ast/parser/Scanners.scala
@@ -226,7 +226,7 @@ trait Scanners extends ScannersCommon {
      *  RPAREN    if region starts with '('
      *  RBRACKET  if region starts with '['
      *  RBRACE    if region starts with '{'
-     *  ARROW     if region starts with `case'
+     *  ARROW     if region starts with 'case'
      *  STRINGLIT if region is a string interpolation expression starting with '${'
      *            (the STRINGLIT appears twice in succession on the stack iff the
      *             expression is a multiline string literal).
@@ -515,7 +515,7 @@ trait Scanners extends ScannersCommon {
               charLitOr(getIdentRest)
             else if (isOperatorPart(ch) && (ch != '\\'))
               charLitOr(getOperatorRest)
-            else {
+            else if (!isAtEnd && (ch != SU && ch != CR && ch != LF || isUnicodeEscape)) {
               getLitChar()
               if (ch == '\'') {
                 nextChar()
@@ -525,6 +525,8 @@ trait Scanners extends ScannersCommon {
                 syntaxError("unclosed character literal")
               }
             }
+            else
+              syntaxError("unclosed character literal")
           }
           fetchSingleQuote()
         case '.' =>
@@ -690,7 +692,7 @@ trait Scanners extends ScannersCommon {
 
     private def unclosedStringLit(): Unit = syntaxError("unclosed string literal")
 
-    private def getRawStringLit(): Unit = {
+    @tailrec private def getRawStringLit(): Unit = {
       if (ch == '\"') {
         nextRawChar()
         if (isTripleQuote()) {
@@ -707,7 +709,7 @@ trait Scanners extends ScannersCommon {
       }
     }
 
-    @scala.annotation.tailrec private def getStringPart(multiLine: Boolean): Unit = {
+    @tailrec private def getStringPart(multiLine: Boolean): Unit = {
       def finishStringPart() = {
         setStrVal()
         token = STRINGPART
diff --git a/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala b/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala
index 01eff71057..a927097b62 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala
@@ -2016,7 +2016,7 @@ abstract class GenICode extends SubComponent {
        *
        *  This could result in unreachable code which has to be cleaned up later, e.g. if the try and all the exception
        *  handlers always end in RETURN then there will be no "normal" flow out of the try/catch/finally.
-       *  Later reachability analysis will remove unreacahble code.
+       *  Later reachability analysis will remove unreachable code.
        */
       def Try(body: Context => Context,
               handlers: List[(Symbol, TypeKind, Context => Context)],
@@ -2060,7 +2060,7 @@ abstract class GenICode extends SubComponent {
         if (settings.YdisableUnreachablePrevention || !outerCtx.bb.ignore) {
           if (finalizer != EmptyTree) {
             val exh = outerCtx.newExceptionHandler(NoSymbol, finalizer.pos) // finalizer covers exception handlers
-            this.addActiveHandler(exh)  // .. and body aswell
+            this.addActiveHandler(exh)  // .. and body as well
             val exhStartCtx = finalizerCtx.enterExceptionHandler(exh)
             exhStartCtx.bb killIf outerCtx.bb.ignore
             val exception = exhStartCtx.makeLocal(finalizer.pos, ThrowableTpe, "exc")
diff --git a/src/compiler/scala/tools/nsc/backend/icode/ICodeCheckers.scala b/src/compiler/scala/tools/nsc/backend/icode/ICodeCheckers.scala
index 843648282b..0f17b5d694 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/ICodeCheckers.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/ICodeCheckers.scala
@@ -20,7 +20,7 @@ abstract class ICodeCheckers {
    *  </p>
    *  <ul>
    *    <li>
-   *      for primitive operations: the type and numer of operands match
+   *      for primitive operations: the type and number of operands match
    *      the type of the operation
    *    </li>
    *    <li>
diff --git a/src/compiler/scala/tools/nsc/backend/jvm/BCodeBodyBuilder.scala b/src/compiler/scala/tools/nsc/backend/jvm/BCodeBodyBuilder.scala
index 22ac8f84d4..e5eb0b79d5 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/BCodeBodyBuilder.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/BCodeBodyBuilder.scala
@@ -92,8 +92,8 @@ abstract class BCodeBodyBuilder extends BCodeSkelBuilder {
 
     def genThrow(expr: Tree): BType = {
       val thrownKind = tpeTK(expr)
-      // `throw null` is valid although scala.Null (as defined in src/libray-aux) isn't a subtype of Throwable.
-      // Similarly for scala.Nothing (again, as defined in src/libray-aux).
+      // `throw null` is valid although scala.Null (as defined in src/library-aux) isn't a subtype of Throwable.
+      // Similarly for scala.Nothing (again, as defined in src/library-aux).
       assert(thrownKind.isNullType || thrownKind.isNothingType || thrownKind.asClassBType.isSubtypeOf(ThrowableReference).get)
       genLoad(expr, thrownKind)
       lineNumber(expr)
diff --git a/src/compiler/scala/tools/nsc/backend/jvm/BTypes.scala b/src/compiler/scala/tools/nsc/backend/jvm/BTypes.scala
index c8ba0d9dbc..aff2d2d8c9 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/BTypes.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/BTypes.scala
@@ -1144,7 +1144,7 @@ object BTypes {
    *                               The map is indexed by the string s"$name$descriptor" (to
    *                               disambiguate overloads).
    *
-   * @param warning                Contains an warning message if an error occured when building this
+   * @param warning                Contains an warning message if an error occurred when building this
    *                               InlineInfo, for example if some classfile could not be found on
    *                               the classpath. This warning can be reported later by the inliner.
    */
diff --git a/src/compiler/scala/tools/nsc/backend/jvm/GenASM.scala b/src/compiler/scala/tools/nsc/backend/jvm/GenASM.scala
index 7096f16d75..7883ce7ffa 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/GenASM.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/GenASM.scala
@@ -492,8 +492,8 @@ abstract class GenASM extends SubComponent with BytecodeWriters { self =>
      *        generic classes or interfaces.
      *
      * @param superName the internal of name of the super class. For interfaces,
-     *        the super class is {@link Object}. May be <tt>null</tt>, but
-     *        only for the {@link Object} class.
+     *        the super class is [[Object]]. May be <tt>null</tt>, but
+     *        only for the [[Object]] class.
      *
      * @param interfaces the internal names of the class's interfaces (see
      *        {@link Type#getInternalName() getInternalName}). May be
@@ -529,6 +529,10 @@ abstract class GenASM extends SubComponent with BytecodeWriters { self =>
         case e: java.lang.RuntimeException if e.getMessage != null && (e.getMessage contains "too large!") =>
           reporter.error(sym.pos,
             s"Could not write class $jclassName because it exceeds JVM code size limits. ${e.getMessage}")
+        case e: java.io.IOException if e.getMessage != null && (e.getMessage contains "File name too long")  =>
+          reporter.error(sym.pos, e.getMessage + "\n" +
+            "This can happen on some encrypted or legacy file systems.  Please see SI-3623 for more details.")
+
       }
     }
 
@@ -2693,7 +2697,7 @@ abstract class GenASM extends SubComponent with BytecodeWriters { self =>
               case CMPG =>
                 (kind: @unchecked) match {
                   case FLOAT  => emit(Opcodes.FCMPG)
-                  case DOUBLE => emit(Opcodes.DCMPL) // TODO bug? why not DCMPG? http://docs.oracle.com/javase/specs/jvms/se5.0/html/Instructions2.doc3.html
+                  case DOUBLE => emit(Opcodes.DCMPL) // TODO bug? why not DCMPG? http://docs.oracle.com/javase/specs/jvms/se6/html/Instructions2.doc3.html
 
                 }
             }
diff --git a/src/compiler/scala/tools/nsc/backend/jvm/analysis/package.scala b/src/compiler/scala/tools/nsc/backend/jvm/analysis/package.scala
index c50648acd9..f1ac703532 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/analysis/package.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/analysis/package.scala
@@ -1,7 +1,7 @@
 package scala.tools.nsc.backend.jvm
 
 /**
- * Summary on the ASM ananlyzer framework
+ * Summary on the ASM analyzer framework
  * --------------------------------------
  *
  * Value
diff --git a/src/compiler/scala/tools/nsc/backend/jvm/opt/ClosureOptimizer.scala b/src/compiler/scala/tools/nsc/backend/jvm/opt/ClosureOptimizer.scala
index 5d3b7ff272..fb7dd16909 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/opt/ClosureOptimizer.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/opt/ClosureOptimizer.scala
@@ -367,7 +367,7 @@ class ClosureOptimizer[BT <: BTypes](val btypes: BT) {
   }
 
   /**
-   * Stores a local varaible index the opcode offset required for operating on that variable.
+   * Stores a local variable index the opcode offset required for operating on that variable.
    *
    * The xLOAD / xSTORE opcodes are in the following sequence: I, L, F, D, A, so the offset for
    * a local variable holding a reference (`A`) is 4. See also method `getOpcode` in [[scala.tools.asm.Type]].
diff --git a/src/compiler/scala/tools/nsc/backend/jvm/opt/Inliner.scala b/src/compiler/scala/tools/nsc/backend/jvm/opt/Inliner.scala
index 20256ca63b..baa747492f 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/opt/Inliner.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/opt/Inliner.scala
@@ -341,7 +341,7 @@ class Inliner[BT <: BTypes](val btypes: BT) {
 
     clonedInstructions.insert(argStores)
 
-    // label for the exit of the inlined functions. xRETURNs are rplaced by GOTOs to this label.
+    // label for the exit of the inlined functions. xRETURNs are replaced by GOTOs to this label.
     val postCallLabel = newLabelNode
     clonedInstructions.add(postCallLabel)
 
@@ -704,9 +704,9 @@ class Inliner[BT <: BTypes](val btypes: BT) {
         //  - a method name+type
         //
         // execution [3]
-        //  - resolve the CSP, yielding the boostrap method handle, the static args and the name+type
+        //  - resolve the CSP, yielding the bootstrap method handle, the static args and the name+type
         //    - resolution entails accessibility checking [4]
-        //  - execute the `invoke` method of the boostrap method handle (which is signature polymorphic, check its javadoc)
+        //  - execute the `invoke` method of the bootstrap method handle (which is signature polymorphic, check its javadoc)
         //    - the descriptor for the call is made up from the actual arguments on the stack:
         //      - the first parameters are "MethodHandles.Lookup, String, MethodType", then the types of the constant arguments,
         //      - the return type is CallSite
diff --git a/src/compiler/scala/tools/nsc/io/Jar.scala b/src/compiler/scala/tools/nsc/io/Jar.scala
index 2967f67e9c..efb026cdff 100644
--- a/src/compiler/scala/tools/nsc/io/Jar.scala
+++ b/src/compiler/scala/tools/nsc/io/Jar.scala
@@ -154,7 +154,7 @@ object Jar {
     def update(key: Attributes.Name, value: String) = attrs.put(key, value)
   }
 
-  // See http://download.java.net/jdk7/docs/api/java/nio/file/Path.html
+  // See http://docs.oracle.com/javase/7/docs/api/java/nio/file/Path.html
   // for some ideas.
   private val ZipMagicNumber = List[Byte](80, 75, 3, 4)
   private def magicNumberIsZip(f: Path) = f.isFile && (f.toFile.bytes().take(4).toList == ZipMagicNumber)
diff --git a/src/compiler/scala/tools/nsc/transform/AddInterfaces.scala b/src/compiler/scala/tools/nsc/transform/AddInterfaces.scala
index 79776485de..82e7c76409 100644
--- a/src/compiler/scala/tools/nsc/transform/AddInterfaces.scala
+++ b/src/compiler/scala/tools/nsc/transform/AddInterfaces.scala
@@ -111,7 +111,7 @@ abstract class AddInterfaces extends InfoTransform { self: Erasure =>
     impl setInfo new LazyImplClassType(iface)
   }
 
-  /** Return the implementation class of a trait; create a new one of one does not yet exist */
+  /** Return the implementation class of a trait; create a new one if one does not yet exist */
   def implClass(iface: Symbol): Symbol = {
     iface.info
 
diff --git a/src/compiler/scala/tools/nsc/transform/Constructors.scala b/src/compiler/scala/tools/nsc/transform/Constructors.scala
index 7c66bda46b..48eb878e2a 100644
--- a/src/compiler/scala/tools/nsc/transform/Constructors.scala
+++ b/src/compiler/scala/tools/nsc/transform/Constructors.scala
@@ -137,7 +137,7 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL {
    *       and thus may only be accessed from value or method definitions owned by the current class
    *       (ie there's no point drilling down into nested classes).
    *
-   *   (d) regarding candidates in (b), they are accesible from all places listed in (c) and in addition
+   *   (d) regarding candidates in (b), they are accessible from all places listed in (c) and in addition
    *       from nested classes (nested at any number of levels).
    *
    * In all cases, we're done with traversing as soon as all candidates have been ruled out.
@@ -396,9 +396,9 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL {
         }
 
         if (stat1 eq stat) {
-          assert(ctorParams(genericClazz).length == constrInfo.constrParams.length)
+          assert(ctorParams(genericClazz).length == primaryConstrParams.length)
           // this is just to make private fields public
-          (new specializeTypes.ImplementationAdapter(ctorParams(genericClazz), constrInfo.constrParams, null, true))(stat1)
+          (new specializeTypes.ImplementationAdapter(ctorParams(genericClazz), primaryConstrParams, null, true))(stat1)
 
           val stat2 = rewriteArrayUpdate(stat1)
           // statements coming from the original class need retyping in the current context
@@ -435,16 +435,16 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL {
       //   postfix = postfix.tail
       // }
 
-      if (shouldGuard && usesSpecializedField && stats.nonEmpty) {
+      if (guardSpecializedFieldInit && intoConstructor.usesSpecializedField && stats.nonEmpty) {
         // save them for duplication in the specialized subclass
         guardedCtorStats(clazz) = stats
-        ctorParams(clazz) = constrInfo.constrParams
+        ctorParams(clazz) = primaryConstrParams
 
         val tree =
           If(
             Apply(
               CODE.NOT (
-               Apply(gen.mkAttributedRef(specializedFlag), List())),
+               Apply(gen.mkAttributedRef(hasSpecializedFieldsSym), List())),
               List()),
             Block(stats, Literal(Constant(()))),
             EmptyTree)
@@ -476,27 +476,17 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL {
     val stats = impl.body          // the transformed template body
     val localTyper = typer.atOwner(impl, clazz)
 
-    val specializedFlag: Symbol = clazz.info.decl(nme.SPECIALIZED_INSTANCE)
-    val shouldGuard = (specializedFlag != NoSymbol) && !clazz.hasFlag(SPECIALIZED)
-
-    val isDelayedInitSubclass = (clazz isSubClass DelayedInitClass)
-
-    case class ConstrInfo(
-      constr: DefDef,               // The primary constructor
-      constrParams: List[Symbol],   // ... and its parameters
-      constrBody: Block             // ... and its body
-    )
-    // decompose primary constructor into the three entities above.
-    val constrInfo: ConstrInfo = {
-      val ddef = (stats find (_.symbol.isPrimaryConstructor))
-      ddef match {
-        case Some(ddef @ DefDef(_, _, _, List(vparams), _, rhs @ Block(_, _))) =>
-          ConstrInfo(ddef, vparams map (_.symbol), rhs)
-        case x =>
-          abort("no constructor in template: impl = " + impl)
-      }
-    }
-    import constrInfo._
+    val hasSpecializedFieldsSym   = clazz.info.decl(nme.SPECIALIZED_INSTANCE)
+    // The constructor of a non-specialized class that has specialized subclasses
+    // should use `q"${hasSpecializedFieldsSym}()"` to guard the initialization of specialized fields.
+    val guardSpecializedFieldInit = (hasSpecializedFieldsSym != NoSymbol) && !clazz.hasFlag(SPECIALIZED)
+
+    val isDelayedInitSubclass = clazz isSubClass DelayedInitClass
+
+    // find and dissect primary constructor
+    val (primaryConstr, primaryConstrParams, primaryConstrBody) = stats collectFirst {
+      case dd@DefDef(_, _, _, vps :: Nil, _, rhs: Block) if dd.symbol.isPrimaryConstructor => (dd, vps map (_.symbol), rhs)
+    } getOrElse abort("no constructor in template: impl = " + impl)
 
     // The parameter accessor fields which are members of the class
     val paramAccessors = clazz.constrParamAccessors
@@ -509,27 +499,26 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL {
     def parameterNamed(name: Name): Symbol = {
       def matchesName(param: Symbol) = param.name == name || param.name.startsWith(name + nme.NAME_JOIN_STRING)
 
-      (constrParams filter matchesName) match {
-        case Nil    => abort(name + " not in " + constrParams)
+      primaryConstrParams filter matchesName match {
+        case Nil    => abort(name + " not in " + primaryConstrParams)
         case p :: _ => p
       }
     }
 
-    /*
-     * `usesSpecializedField` makes a difference in deciding whether constructor-statements
-     * should be guarded in a `shouldGuard` class, ie in a class that's the generic super-class of
-     * one or more specialized sub-classes.
-     *
-     * Given that `usesSpecializedField` isn't read for any other purpose than the one described above,
-     * we skip setting `usesSpecializedField` in case the current class isn't `shouldGuard` to start with.
-     * That way, trips to a map in `specializeTypes` are saved.
-     */
-    var usesSpecializedField: Boolean = false
-
     // A transformer for expressions that go into the constructor
-    private class IntoCtorTransformer extends Transformer {
-
-      private def isParamRef(sym: Symbol) = (sym.isParamAccessor && sym.owner == clazz)
+    object intoConstructor extends Transformer {
+      /*
+      * `usesSpecializedField` makes a difference in deciding whether constructor-statements
+      * should be guarded in a `guardSpecializedFieldInit` class, ie in a class that's the generic super-class of
+      * one or more specialized sub-classes.
+      *
+      * Given that `usesSpecializedField` isn't read for any other purpose than the one described above,
+      * we skip setting `usesSpecializedField` in case the current class isn't `guardSpecializedFieldInit` to start with.
+      * That way, trips to a map in `specializeTypes` are saved.
+      */
+      var usesSpecializedField: Boolean = false
+
+      private def isParamRef(sym: Symbol) = sym.isParamAccessor && sym.owner == clazz
 
       // Terminology: a stationary location is never written after being read.
       private def isStationaryParamRef(sym: Symbol) = (
@@ -548,10 +537,9 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL {
        *         (b.2) the constructor in the specialized (sub-)class.
        *   (c) isn't part of a DelayedInit subclass.
        */
-      private def canBeSupplanted(sym: Symbol) = (!isDelayedInitSubclass && isStationaryParamRef(sym) && !possiblySpecialized(sym))
+      private def canBeSupplanted(sym: Symbol) = !isDelayedInitSubclass && isStationaryParamRef(sym) && !possiblySpecialized(sym)
 
       override def transform(tree: Tree): Tree = tree match {
-
         case Apply(Select(This(_), _), List()) =>
           // references to parameter accessor methods of own class become references to parameters
           // outer accessors become references to $outer parameter
@@ -566,7 +554,7 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL {
           // references to parameter accessor field of own class become references to parameters
           gen.mkAttributedIdent(parameter(tree.symbol)) setPos tree.pos
 
-        case Select(_, _) if shouldGuard => // reasoning behind this guard in the docu of `usesSpecializedField`
+        case Select(_, _) if guardSpecializedFieldInit => // reasoning behind this guard in the docu of `usesSpecializedField`
           if (possiblySpecialized(tree.symbol)) {
             usesSpecializedField = true
           }
@@ -576,18 +564,10 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL {
           super.transform(tree)
       }
 
-    }
-
-    private val intoConstructorTransformer = new IntoCtorTransformer
-
-    // Move tree into constructor, take care of changing owner from `oldowner` to constructor symbol
-    def intoConstructor(oldowner: Symbol, tree: Tree) =
-      intoConstructorTransformer transform tree.changeOwner(oldowner -> constr.symbol)
-
-    // Should tree be moved in front of super constructor call?
-    def canBeMoved(tree: Tree) = tree match {
-      case ValDef(mods, _, _, _) => (mods hasFlag PRESUPER | PARAMACCESSOR)
-      case _                     => false
+      // Move tree into constructor, take care of changing owner from `oldowner` to constructor symbol
+      def apply(oldowner: Symbol, tree: Tree) =
+        if (tree eq EmptyTree) tree
+        else transform(tree.changeOwner(oldowner -> primaryConstr.symbol))
     }
 
     // Create an assignment to class field `to` with rhs `from`
@@ -629,10 +609,10 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL {
     val classInitStatBuf = new ListBuffer[Tree]
 
     // generate code to copy pre-initialized fields
-    for (stat <- constrBody.stats) {
+    for (stat <- primaryConstrBody.stats) {
       constrStatBuf += stat
       stat match {
-        case ValDef(mods, name, _, _) if (mods hasFlag PRESUPER) =>
+        case ValDef(mods, name, _, _) if mods hasFlag PRESUPER =>
           // stat is the constructor-local definition of the field value
           val fields = presupers filter (_.getterName == name)
           assert(fields.length == 1)
@@ -643,45 +623,48 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL {
       }
     }
 
-    // Triage all template definitions to go into defBuf/auxConstructorBuf, constrStatBuf, or constrPrefixBuf.
-    for (stat <- stats) stat match {
-      case DefDef(_,_,_,_,_,rhs) =>
-        // methods with constant result type get literals as their body
-        // all methods except the primary constructor go into template
-        stat.symbol.tpe match {
-          case MethodType(List(), tp @ ConstantType(c)) =>
-            defBuf += deriveDefDef(stat)(Literal(c) setPos _.pos setType tp)
-          case _ =>
-            if (stat.symbol.isPrimaryConstructor) ()
-            else if (stat.symbol.isConstructor) auxConstructorBuf += stat
-            else defBuf += stat
-        }
-      case ValDef(mods, _, _, rhs) if !mods.hasStaticFlag =>
+
+    for (stat <- stats) {
+      val statSym = stat.symbol
+
+      stat match {
+        // recurse on class definition, store in defBuf
+        case _: ClassDef => defBuf += new ConstructorTransformer(unit).transform(stat)
+
+        // methods (except primary constructor) go into template
+        // (non-primary ctors --> auxConstructorBuf / regular defs --> defBuf)
+        case _: DefDef if statSym.isPrimaryConstructor => ()
+        case _: DefDef if statSym.isConstructor        => auxConstructorBuf += stat
+        case _: DefDef                                 => defBuf += stat
+
         // val defs with constant right-hand sides are eliminated.
-        // for all other val defs, an empty valdef goes into the template and
-        // the initializer goes as an assignment into the constructor
-        // if the val def is an early initialized or a parameter accessor, it goes
-        // before the superclass constructor call, otherwise it goes after.
-        // Lazy vals don't get the assignment in the constructor.
-        if (!stat.symbol.tpe.isInstanceOf[ConstantType]) {
-          if (rhs != EmptyTree && !stat.symbol.isLazy) {
-            val rhs1 = intoConstructor(stat.symbol, rhs)
-            (if (canBeMoved(stat)) constrPrefixBuf else constrStatBuf) += mkAssign(
-              stat.symbol, rhs1)
+        case _: ValDef if statSym.info.isInstanceOf[ConstantType] => ()
+
+        // For all other val defs, an empty valdef goes into the template.
+        // Additionally, non-lazy vals are initialized by an assignment in:
+        //   - the class initializer (static),
+        //   - the constructor, before the super call (early initialized or a parameter accessor),
+        //   - the constructor, after the super call (regular val).
+        case ValDef(mods, _, _, rhs) =>
+          val initializingRhs =
+            if (statSym.isLazy) EmptyTree
+            else if (!mods.hasStaticFlag) intoConstructor(statSym, rhs)
+            else rhs
+
+          if (initializingRhs ne EmptyTree) {
+            val initPhase =
+              if (mods hasFlag STATIC) classInitStatBuf
+              else if (mods hasFlag PRESUPER | PARAMACCESSOR) constrPrefixBuf
+              else constrStatBuf
+
+            initPhase += mkAssign(statSym, initializingRhs)
           }
+
           defBuf += deriveValDef(stat)(_ => EmptyTree)
-        }
-      case ValDef(_, _, _, rhs) =>
-        // Add static initializer statements to classInitStatBuf and remove the rhs from the val def.
-        classInitStatBuf += mkAssign(stat.symbol, rhs)
-        defBuf += deriveValDef(stat)(_ => EmptyTree)
-
-      case ClassDef(_, _, _, _) =>
-        // classes are treated recursively, and left in the template
-        defBuf += new ConstructorTransformer(unit).transform(stat)
-      case _ =>
+
         // all other statements go into the constructor
-        constrStatBuf += intoConstructor(impl.symbol, stat)
+        case _ => constrStatBuf += intoConstructor(impl.symbol, stat)
+      }
     }
 
     populateOmittables()
@@ -716,12 +699,12 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL {
     rewriteDelayedInit()
 
     // Assemble final constructor
-    defBuf += deriveDefDef(constr)(_ =>
+    defBuf += deriveDefDef(primaryConstr)(_ =>
       treeCopy.Block(
-        constrBody,
+        primaryConstrBody,
         paramInits ::: constrPrefixBuf.toList ::: uptoSuperStats :::
           guardSpecializedInitializer(remainingConstrStats),
-        constrBody.expr))
+        primaryConstrBody.expr))
 
     // Followed by any auxiliary constructors
     defBuf ++= auxConstructorBuf
@@ -732,6 +715,7 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL {
 
     // Eliminate all field definitions that can be dropped from template
     val templateWithoutOmittables: Template = deriveTemplate(impl)(_ => defBuf.toList filter (stat => mustBeKept(stat.symbol)))
+
     //  Add the static initializers
     val transformed: Template = addStaticInits(templateWithoutOmittables, classInitStatBuf, localTyper)
 
diff --git a/src/compiler/scala/tools/nsc/transform/Delambdafy.scala b/src/compiler/scala/tools/nsc/transform/Delambdafy.scala
index ddf003bb98..33fd5d0461 100644
--- a/src/compiler/scala/tools/nsc/transform/Delambdafy.scala
+++ b/src/compiler/scala/tools/nsc/transform/Delambdafy.scala
@@ -281,7 +281,7 @@ abstract class Delambdafy extends Transform with TypingTransformers with ast.Tre
         val parents = addSerializable(abstractFunctionErasedType)
         val funOwner = originalFunction.symbol.owner
 
-        // TODO harmonize the naming of delamdafy anon-fun classes with those spun up by Uncurry
+        // TODO harmonize the naming of delambdafy anon-fun classes with those spun up by Uncurry
         //      - make `anonClass.isAnonymousClass` true.
         //      - use `newAnonymousClassSymbol` or push the required variations into a similar factory method
         //      - reinstate the assertion in `Erasure.resolveAnonymousBridgeClash`
diff --git a/src/compiler/scala/tools/nsc/transform/Mixin.scala b/src/compiler/scala/tools/nsc/transform/Mixin.scala
index a079a76ce7..00a994fe87 100644
--- a/src/compiler/scala/tools/nsc/transform/Mixin.scala
+++ b/src/compiler/scala/tools/nsc/transform/Mixin.scala
@@ -778,7 +778,7 @@ abstract class Mixin extends InfoTransform with ast.TreeDSL {
         val defSym = clazz.newMethod(nme.newLazyValSlowComputeName(lzyVal.name.toTermName), lzyVal.pos, PRIVATE)
         val params = defSym newSyntheticValueParams args.map(_.symbol.tpe)
         defSym setInfoAndEnter MethodType(params, lzyVal.tpe.resultType)
-        val rhs: Tree = (gen.mkSynchronizedCheck(attrThis, cond, syncBody, stats)).changeOwner(currentOwner -> defSym)
+        val rhs: Tree = gen.mkSynchronizedCheck(attrThis, cond, syncBody, stats).changeOwner(currentOwner -> defSym)
         val strictSubst = new TreeSymSubstituterWithCopying(args.map(_.symbol), params)
         addDef(position(defSym), DefDef(defSym, strictSubst(BLOCK(rhs, retVal))))
         defSym
diff --git a/src/compiler/scala/tools/nsc/transform/UnCurry.scala b/src/compiler/scala/tools/nsc/transform/UnCurry.scala
index 72e2174bf8..57639a94c7 100644
--- a/src/compiler/scala/tools/nsc/transform/UnCurry.scala
+++ b/src/compiler/scala/tools/nsc/transform/UnCurry.scala
@@ -582,6 +582,7 @@ abstract class UnCurry extends InfoTransform
           }
 
         case dd @ DefDef(_, _, _, vparamss0, _, rhs0) =>
+          val ddSym = dd.symbol
           val (newParamss, newRhs): (List[List[ValDef]], Tree) =
             if (dependentParamTypeErasure isDependent dd)
               dependentParamTypeErasure erase dd
@@ -593,11 +594,22 @@ abstract class UnCurry extends InfoTransform
               (vparamss1, rhs0)
             }
 
+          // A no-arg method with ConstantType result type can safely be reduced to the corresponding Literal
+          // (only pure methods are typed as ConstantType). We could also do this for methods with arguments,
+          // after ensuring the arguments are not referenced.
+          val literalRhsIfConst =
+            if (newParamss.head.isEmpty) { // We know newParamss.length == 1 from above
+              ddSym.info.resultType match {
+                case tp@ConstantType(value) => Literal(value) setType tp setPos newRhs.pos // inlining of gen.mkAttributedQualifier(tp)
+                case _ => newRhs
+              }
+            } else newRhs
+
           val flatdd = copyDefDef(dd)(
             vparamss = newParamss,
-            rhs = nonLocalReturnKeys get dd.symbol match {
-              case Some(k) => atPos(newRhs.pos)(nonLocalReturnTry(newRhs, k, dd.symbol))
-              case None    => newRhs
+            rhs = nonLocalReturnKeys get ddSym match {
+              case Some(k) => atPos(newRhs.pos)(nonLocalReturnTry(literalRhsIfConst, k, ddSym))
+              case None    => literalRhsIfConst
             }
           )
           addJavaVarargsForwarders(dd, flatdd)
@@ -691,9 +703,46 @@ abstract class UnCurry extends InfoTransform
               // declared type and assign this to a synthetic val. Later, we'll patch
               // the method body to refer to this, rather than the parameter.
               val tempVal: ValDef = {
+                // SI-9442: using the "uncurry-erased" type (the one after the uncurry phase) can lead to incorrect 
+                // tree transformations. For example, compiling:
+                // ```
+                //   def foo(c: Ctx)(l: c.Tree): Unit = {
+                //     val l2: c.Tree = l
+                //   }
+                // ```
+                // Results in the following AST:
+                // ```
+                //   def foo(c: Ctx, l: Ctx#Tree): Unit = {
+                //     val l$1: Ctx#Tree = l.asInstanceOf[Ctx#Tree]
+                //     val l2: c.Tree = l$1 // no, not really, it's not.
+                //   }
+                // ```
+                // Of course, this is incorrect, since `l$1` has type `Ctx#Tree`, which is not a subtype of `c.Tree`.
+                //
+                // So what we need to do is to use the pre-uncurry type when creating `l$1`, which is `c.Tree` and is
+                // correct. Now, there are two additional problems:
+                // 1. when varargs and byname params are involved, the uncurry transformation desugares these special
+                //    cases to actual typerefs, eg:
+                //    ```
+                //           T*  ~> Seq[T] (Scala-defined varargs)
+                //           T*  ~> Array[T] (Java-defined varargs)
+                //           =>T ~> Function0[T] (by name params)
+                //    ```
+                //    we use the DesugaredParameterType object (defined in scala.reflect.internal.transform.UnCurry)
+                //    to redo this desugaring manually here
+                // 2. the type needs to be normalized, since `gen.mkCast` checks this (no HK here, just aliases have
+                //    to be expanded before handing the type to `gen.mkAttributedCast`, which calls `gen.mkCast`)
+                val info0 = 
+                  enteringUncurry(p.symbol.info) match {
+                    case DesugaredParameterType(desugaredTpe) =>
+                      desugaredTpe
+                    case tpe =>
+                      tpe
+                  }
+                val info = info0.normalize
                 val tempValName = unit freshTermName (p.name + "$")
-                val newSym = dd.symbol.newTermSymbol(tempValName, p.pos, SYNTHETIC).setInfo(p.symbol.info)
-                atPos(p.pos)(ValDef(newSym, gen.mkAttributedCast(Ident(p.symbol), p.symbol.info)))
+                val newSym = dd.symbol.newTermSymbol(tempValName, p.pos, SYNTHETIC).setInfo(info)
+                atPos(p.pos)(ValDef(newSym, gen.mkAttributedCast(Ident(p.symbol), info)))
               }
               Packed(newParam, tempVal)
             }
diff --git a/src/compiler/scala/tools/nsc/typechecker/Checkable.scala b/src/compiler/scala/tools/nsc/typechecker/Checkable.scala
index 8bcd5e6f12..2b6a4c763a 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Checkable.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Checkable.scala
@@ -44,7 +44,7 @@ import scala.language.postfixOps
  *  which is essentially the intersection of X and |P|, where |P| is
  *  the erasure of P.  If XR <: P, then no warning is emitted.
  *
- *  We evaluate "X with conform to P" by checking `X <: P_wild, where
+ *  We evaluate "X with conform to P" by checking `X <: P_wild`, where
  *  P_wild is the result of substituting wildcard types in place of
  *  pattern type variables. This is intentionally stricter than
  *  (X matchesPattern P), see SI-8597 for motivating test cases.
diff --git a/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala b/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala
index b0bd9977a8..c9d3b3da96 100644
--- a/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala
@@ -1105,7 +1105,7 @@ trait ContextErrors {
       def GetterDefinedTwiceError(getter: Symbol) =
         issueSymbolTypeError(getter, getter+" is defined twice")
 
-      def ValOrValWithSetterSuffixError(tree: Tree) =
+      def ValOrVarWithSetterSuffixError(tree: Tree) =
         issueNormalTypeError(tree, "Names of vals or vars may not end in `_='")
 
       def PrivateThisCaseClassParameterError(tree: Tree) =
@@ -1212,7 +1212,8 @@ trait ContextErrors {
 
     import definitions._
 
-    def AmbiguousImplicitError(info1: ImplicitInfo, info2: ImplicitInfo,
+    def AmbiguousImplicitError(info1: ImplicitInfo, tree1: Tree,
+                               info2: ImplicitInfo, tree2: Tree,
                                pre1: String, pre2: String, trailer: String)
                                (isView: Boolean, pt: Type, tree: Tree)(implicit context0: Context) = {
       if (!info1.tpe.isErroneous && !info2.tpe.isErroneous) {
@@ -1248,10 +1249,20 @@ trait ContextErrors {
             if (explanation == "") "" else "\n" + explanation
           )
         }
+
+        def treeTypeArgs(annotatedTree: Tree) = annotatedTree match {
+          case TypeApply(_, args) => args.map(_.toString)
+          case _ => Nil
+        }
+
         context.issueAmbiguousError(AmbiguousImplicitTypeError(tree,
-          if (isView) viewMsg
-          else s"ambiguous implicit values:\n${coreMsg}match expected type $pt")
-        )
+          (tree1.symbol, tree2.symbol) match {
+            case (ImplicitAmbiguousMsg(msg), _) => msg.format(treeTypeArgs(tree1))
+            case (_, ImplicitAmbiguousMsg(msg)) => msg.format(treeTypeArgs(tree2))
+            case (_, _) if isView => viewMsg
+            case (_, _) => s"ambiguous implicit values:\n${coreMsg}match expected type $pt"
+          }
+        ))
       }
     }
 
diff --git a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
index 196b137a3e..2fb3ae41e2 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
@@ -110,10 +110,10 @@ trait Implicits {
    * Ignore their constr field! The list of type constraints returned along with each tree specifies the constraints that
    * must be met by the corresponding type parameter in `tpars` (for the returned implicit view to be valid).
    *
-   * @arg tp      from-type for the implicit conversion
-   * @arg context search implicits here
-   * @arg tpars   symbols that should be considered free type variables
-   *              (implicit search should not try to solve them, just track their constraints)
+   * @param tp      from-type for the implicit conversion
+   * @param context search implicits here
+   * @param tpars   symbols that should be considered free type variables
+   *                (implicit search should not try to solve them, just track their constraints)
    */
   def allViewsFrom(tp: Type, context: Context, tpars: List[Symbol]): List[(SearchResult, List[TypeConstraint])] = {
     // my untouchable typevars are better than yours (they can't be constrained by them)
@@ -324,8 +324,10 @@ trait Implicits {
    */
   class ImplicitSearch(tree: Tree, pt: Type, isView: Boolean, context0: Context, pos0: Position = NoPosition) extends Typer(context0) with ImplicitsContextErrors {
     val searchId = implicitSearchId()
-    private def typingLog(what: String, msg: => String) =
-      typingStack.printTyping(tree, f"[search #$searchId] $what $msg")
+    private def typingLog(what: String, msg: => String) = {
+      if (printingOk(tree))
+        typingStack.printTyping(f"[search #$searchId] $what $msg")
+    }
 
     import infer._
     if (Statistics.canEnable) Statistics.incCounter(implicitSearchCount)
@@ -885,7 +887,7 @@ trait Implicits {
        *   - find the most likely one
        *   - if it matches, forget about all others it improves upon
        */
-      @tailrec private def rankImplicits(pending: Infos, acc: Infos): Infos = pending match {
+      @tailrec private def rankImplicits(pending: Infos, acc: List[(SearchResult, ImplicitInfo)]): List[(SearchResult, ImplicitInfo)] = pending match {
         case Nil                          => acc
         case firstPending :: otherPending =>
           def firstPendingImproves(alt: ImplicitInfo) =
@@ -912,7 +914,7 @@ trait Implicits {
               val pendingImprovingBest = undoLog undo {
                 otherPending filterNot firstPendingImproves
               }
-              rankImplicits(pendingImprovingBest, firstPending :: acc)
+              rankImplicits(pendingImprovingBest, (newBest, firstPending) :: acc)
           }
       }
 
@@ -928,14 +930,14 @@ trait Implicits {
         // So if there is any element not improved upon by the first it is an error.
         rankImplicits(eligible, Nil) match {
           case Nil            => ()
-          case chosen :: rest =>
-            rest find (alt => !improves(chosen, alt)) match {
-              case Some(competing)  =>
-                AmbiguousImplicitError(chosen, competing, "both", "and", "")(isView, pt, tree)(context)
+          case (chosenResult, chosenInfo) :: rest =>
+            rest find { case (_, alt) => !improves(chosenInfo, alt) } match {
+              case Some((competingResult, competingInfo))  =>
+                AmbiguousImplicitError(chosenInfo, chosenResult.tree, competingInfo, competingResult.tree, "both", "and", "")(isView, pt, tree)(context)
                 return AmbiguousSearchFailure // Stop the search once ambiguity is encountered, see t4457_2.scala
               case _                =>
-                if (isView) chosen.useCountView += 1
-                else chosen.useCountArg += 1
+                if (isView) chosenInfo.useCountView += 1
+                else chosenInfo.useCountArg += 1
             }
         }
 
@@ -1445,9 +1447,9 @@ trait Implicits {
     }
   }
 
-  object ImplicitNotFoundMsg {
-    def unapply(sym: Symbol): Option[(Message)] = sym.implicitNotFoundMsg match {
-      case Some(m) => Some(new Message(sym, m))
+  class ImplicitAnnotationMsg(f: Symbol => Option[String], clazz: Symbol, annotationName: String) {
+    def unapply(sym: Symbol): Option[(Message)] = f(sym) match {
+      case Some(m) => Some(new Message(sym, m, annotationName))
       case None if sym.isAliasType =>
         // perform exactly one step of dealiasing
         // this is necessary because ClassManifests are now aliased to ClassTags
@@ -1459,41 +1461,45 @@ trait Implicits {
     // check the message's syntax: should be a string literal that may contain occurrences of the string "${X}",
     // where `X` refers to a type parameter of `sym`
     def check(sym: Symbol): Option[String] =
-      sym.getAnnotation(ImplicitNotFoundClass).flatMap(_.stringArg(0) match {
-        case Some(m) => new Message(sym, m).validate
-        case None => Some("Missing argument `msg` on implicitNotFound annotation.")
+      sym.getAnnotation(clazz).flatMap(_.stringArg(0) match {
+        case Some(m) => new Message(sym, m, annotationName).validate
+        case None => Some(s"Missing argument `msg` on $annotationName annotation.")
       })
+  }
+
+  object ImplicitNotFoundMsg extends ImplicitAnnotationMsg(_.implicitNotFoundMsg, ImplicitNotFoundClass, "implicitNotFound")
 
+  object ImplicitAmbiguousMsg extends ImplicitAnnotationMsg(_.implicitAmbiguousMsg, ImplicitAmbiguousClass, "implicitAmbiguous")
+
+  class Message(sym: Symbol, msg: String, annotationName: String) {
     // http://dcsobral.blogspot.com/2010/01/string-interpolation-in-scala-with.html
     private val Intersobralator = """\$\{\s*([^}\s]+)\s*\}""".r
 
-    class Message(sym: Symbol, msg: String) {
-      private def interpolate(text: String, vars: Map[String, String]) =
-        Intersobralator.replaceAllIn(text, (_: Regex.Match) match {
-          case Regex.Groups(v) => Regex quoteReplacement vars.getOrElse(v, "")
+    private def interpolate(text: String, vars: Map[String, String]) =
+      Intersobralator.replaceAllIn(text, (_: Regex.Match) match {
+        case Regex.Groups(v) => Regex quoteReplacement vars.getOrElse(v, "")
           // #3915: need to quote replacement string since it may include $'s (such as the interpreter's $iw)
-        })
+      })
 
-      private lazy val typeParamNames: List[String] = sym.typeParams.map(_.decodedName)
-      private def typeArgsAtSym(paramTp: Type) = paramTp.baseType(sym).typeArgs
+    private lazy val typeParamNames: List[String] = sym.typeParams.map(_.decodedName)
+    private def typeArgsAtSym(paramTp: Type) = paramTp.baseType(sym).typeArgs
 
-      def format(paramName: Name, paramTp: Type): String = format(typeArgsAtSym(paramTp) map (_.toString))
+    def format(paramName: Name, paramTp: Type): String = format(typeArgsAtSym(paramTp) map (_.toString))
 
-      def format(typeArgs: List[String]): String =
-        interpolate(msg, Map((typeParamNames zip typeArgs): _*)) // TODO: give access to the name and type of the implicit argument, etc?
+    def format(typeArgs: List[String]): String =
+      interpolate(msg, Map((typeParamNames zip typeArgs): _*)) // TODO: give access to the name and type of the implicit argument, etc?
 
-      def validate: Option[String] = {
-        val refs  = Intersobralator.findAllMatchIn(msg).map(_ group 1).toSet
-        val decls = typeParamNames.toSet
+    def validate: Option[String] = {
+      val refs  = Intersobralator.findAllMatchIn(msg).map(_ group 1).toSet
+      val decls = typeParamNames.toSet
 
-        (refs &~ decls) match {
-          case s if s.isEmpty => None
-          case unboundNames   =>
-            val singular = unboundNames.size == 1
-            val ess      = if (singular) "" else "s"
-            val bee      = if (singular) "is" else "are"
-            Some(s"The type parameter$ess ${unboundNames mkString ", "} referenced in the message of the @implicitNotFound annotation $bee not defined by $sym.")
-        }
+      (refs &~ decls) match {
+        case s if s.isEmpty => None
+        case unboundNames   =>
+          val singular = unboundNames.size == 1
+          val ess      = if (singular) "" else "s"
+          val bee      = if (singular) "is" else "are"
+          Some(s"The type parameter$ess ${unboundNames mkString ", "} referenced in the message of the @$annotationName annotation $bee not defined by $sym.")
       }
     }
   }
diff --git a/src/compiler/scala/tools/nsc/typechecker/Infer.scala b/src/compiler/scala/tools/nsc/typechecker/Infer.scala
index bf705e89ad..a5fdbb5148 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Infer.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Infer.scala
@@ -1375,7 +1375,7 @@ trait Infer extends Checkable {
      *  Otherwise, if there is no best alternative, error.
      *
      *  @param argtpes0 contains the argument types. If an argument is named, as
-     *    "a = 3", the corresponding type is `NamedType("a", Int)'. If the name
+     *    "a = 3", the corresponding type is `NamedType("a", Int)`. If the name
      *    of some NamedType does not exist in an alternative's parameter names,
      *    the type is replaces by `Unit`, i.e. the argument is treated as an
      *    assignment expression.
diff --git a/src/compiler/scala/tools/nsc/typechecker/Macros.scala b/src/compiler/scala/tools/nsc/typechecker/Macros.scala
index 99dd81c7e2..3ed128cbc5 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Macros.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Macros.scala
@@ -55,6 +55,13 @@ trait Macros extends MacroRuntimes with Traces with Helpers {
 
   def globalSettings = global.settings
 
+  /** Obtains a `ClassLoader` instance used for macro expansion.
+   *
+   *  By default a new `ScalaClassLoader` is created using the classpath
+   *  from global and the classloader of self as parent.
+   *
+   *  Mirrors with runtime definitions (e.g. Repl) need to adjust this method.
+   */
   protected def findMacroClassLoader(): ClassLoader = {
     val classpath = global.classPath.asURLs
     macroLogVerbose("macro classloader: initializing from -cp: %s".format(classpath))
@@ -658,7 +665,7 @@ trait Macros extends MacroRuntimes with Traces with Helpers {
       //
       // Situation #2 requires measures to be taken. If we're in it, then noone's going to help us infer
       // the undetermined type params. Therefore we need to do something ourselves or otherwise this
-      // expandee will forever remaing not expanded (see SI-5692). A traditional way out of this conundrum
+      // expandee will forever remain not expanded (see SI-5692). A traditional way out of this conundrum
       // is to call `instantiate` and let the inferencer try to find the way out. It works for simple cases,
       // but sometimes, if the inferencer lacks information, it will be forced to approximate.
       //
diff --git a/src/compiler/scala/tools/nsc/typechecker/MethodSynthesis.scala b/src/compiler/scala/tools/nsc/typechecker/MethodSynthesis.scala
index f3856db552..f3632b144d 100644
--- a/src/compiler/scala/tools/nsc/typechecker/MethodSynthesis.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/MethodSynthesis.scala
@@ -134,28 +134,28 @@ trait MethodSynthesis {
       ImplicitClassWrapper(tree).createAndEnterSymbol()
     }
 
-    def enterGetterSetter(tree: ValDef) {
-      val ValDef(mods, name, _, _) = tree
-      if (nme.isSetterName(name))
-        ValOrValWithSetterSuffixError(tree)
-
-      tree.symbol = (
-        if (mods.isLazy) {
+    // TODO: see if we can link symbol creation & tree derivation by sharing the Field/Getter/Setter factories
+    def enterGetterSetter(tree: ValDef): Unit = {
+      tree.symbol =
+        if (tree.mods.isLazy) {
           val lazyValGetter = LazyValGetter(tree).createAndEnterSymbol()
           enterLazyVal(tree, lazyValGetter)
         } else {
-          if (mods.isPrivateLocal)
-            PrivateThisCaseClassParameterError(tree)
-          val getter = Getter(tree).createAndEnterSymbol()
+          val getter = Getter(tree)
+          val getterSym = getter.createAndEnterSymbol()
+
           // Create the setter if necessary.
-          if (mods.isMutable)
+          if (getter.needsSetter)
             Setter(tree).createAndEnterSymbol()
 
-          // If abstract, the tree gets the getter's symbol.  Otherwise, create a field.
-          if (mods.isDeferred) getter setPos tree.pos
+          // If the getter's abstract the tree gets the getter's symbol,
+          // otherwise, create a field (assume the getter requires storage).
+          // NOTE: we cannot look at symbol info, since we're in the process of deriving them
+          // (luckily, they only matter for lazy vals, which we've ruled out in this else branch,
+          // and `doNotDeriveField` will skip them if `!mods.isLazy`)
+          if (Field.noFieldFor(tree)) getterSym setPos tree.pos
           else enterStrictVal(tree)
         }
-      )
 
       enterBeans(tree)
     }
@@ -177,11 +177,11 @@ trait MethodSynthesis {
     }
 
     def addDerivedTrees(typer: Typer, stat: Tree): List[Tree] = stat match {
-      case vd @ ValDef(mods, name, tpt, rhs) if !noFinishGetterSetter(vd) =>
+      case vd @ ValDef(mods, name, tpt, rhs) if deriveAccessors(vd) && !vd.symbol.isModuleVar =>
         // If we don't save the annotations, they seem to wander off.
         val annotations = stat.symbol.initialize.annotations
         val trees = (
-          allValDefDerived(vd)
+          (field(vd) ::: standardAccessors(vd) ::: beanAccessors(vd))
                 map (acc => atPos(vd.pos.focus)(acc derive annotations))
           filterNot (_ eq EmptyTree)
         )
@@ -221,11 +221,14 @@ trait MethodSynthesis {
         stat :: Nil
       }
 
-    def standardAccessors(vd: ValDef): List[DerivedFromValDef] = (
-      if (vd.mods.isMutable && !vd.mods.isLazy) List(Getter(vd), Setter(vd))
-      else if (vd.mods.isLazy) List(LazyValGetter(vd))
-      else List(Getter(vd))
-    )
+    def standardAccessors(vd: ValDef): List[DerivedFromValDef] =
+      if (vd.mods.isLazy) List(LazyValGetter(vd))
+      else {
+        val getter = Getter(vd)
+        if (getter.needsSetter) List(getter, Setter(vd))
+        else List(getter)
+      }
+
     def beanAccessors(vd: ValDef): List[DerivedFromValDef] = {
       val setter = if (vd.mods.isMutable) List(BeanSetter(vd)) else Nil
       if (vd.symbol hasAnnotation BeanPropertyAttr)
@@ -234,15 +237,8 @@ trait MethodSynthesis {
         BooleanBeanGetter(vd) :: setter
       else Nil
     }
-    def allValDefDerived(vd: ValDef) = {
-      val field = if (vd.mods.isDeferred || (vd.mods.isLazy && hasUnitType(vd.symbol))) Nil
-                  else List(Field(vd))
-      field ::: standardAccessors(vd) ::: beanAccessors(vd)
-    }
 
-    // Take into account annotations so that we keep annotated unit lazy val
-    // to get better error message already from the cps plugin itself
-    def hasUnitType(sym: Symbol) = (sym.tpe.typeSymbol == UnitClass) && sym.tpe.annotations.isEmpty
+    def field(vd: ValDef): List[Field] = if (Field.noFieldFor(vd)) Nil else List(Field(vd))
 
     /** This trait assembles what's needed for synthesizing derived methods.
      *  Important: Typically, instances of this trait are created TWICE for each derived
@@ -260,7 +256,6 @@ trait MethodSynthesis {
       def name: TermName
 
       /** The flags that are retained from the original symbol */
-
       def flagsMask: Long
 
       /** The flags that the derived symbol has in addition to those retained from
@@ -284,8 +279,9 @@ trait MethodSynthesis {
       def enclClass: Symbol
 
       // Final methods to make the rest easier to reason about.
-      final def mods               = tree.mods
-      final def basisSym           = tree.symbol
+      final def mods        = tree.mods
+      final def basisSym    = tree.symbol
+      final def derivedMods = mods & flagsMask | flagsExtra
     }
 
     sealed trait DerivedFromClassDef extends DerivedFromMemberDef {
@@ -305,7 +301,6 @@ trait MethodSynthesis {
       /* Explicit isSetter required for bean setters (beanSetterSym.isSetter is false) */
       final def completer(sym: Symbol) = namerOf(sym).accessorTypeCompleter(tree, isSetter)
       final def fieldSelection         = Select(This(enclClass), basisSym)
-      final def derivedMods: Modifiers = mods & flagsMask | flagsExtra mapAnnotations (_ => Nil)
 
       def derivedSym: Symbol = tree.symbol
       def derivedTree: Tree  = EmptyTree
@@ -314,8 +309,8 @@ trait MethodSynthesis {
       def isDeferred = mods.isDeferred
       def keepClean  = false  // whether annotations whose definitions are not meta-annotated should be kept.
       def validate() { }
-      def createAndEnterSymbol(): Symbol = {
-        val sym = owner.newMethod(name, tree.pos.focus, (tree.mods.flags & flagsMask) | flagsExtra)
+      def createAndEnterSymbol(): MethodSymbol = {
+        val sym = owner.newMethod(name, tree.pos.focus, derivedMods.flags)
         setPrivateWithin(tree, sym)
         enterInScope(sym)
         sym setInfo completer(sym)
@@ -333,7 +328,8 @@ trait MethodSynthesis {
       }
     }
     sealed trait DerivedGetter extends DerivedFromValDef {
-      // TODO
+      // A getter must be accompanied by a setter if the ValDef is mutable.
+      def needsSetter = mods.isMutable
     }
     sealed trait DerivedSetter extends DerivedFromValDef {
       override def isSetter = true
@@ -341,10 +337,13 @@ trait MethodSynthesis {
         case (p :: Nil) :: _  => p
         case _                => NoSymbol
       }
-      private def setterRhs = (
-        if (mods.isDeferred || derivedSym.isOverloaded) EmptyTree
+
+      private def setterRhs = {
+        assert(!derivedSym.isOverloaded, s"Unexpected overloaded setter $derivedSym for $basisSym in $enclClass")
+        if (Field.noFieldFor(tree) || derivedSym.isOverloaded) EmptyTree
         else Assign(fieldSelection, Ident(setterParam))
-      )
+      }
+
       private def setterDef = DefDef(derivedSym, setterRhs)
       override def derivedTree: Tree = if (setterParam == NoSymbol) EmptyTree else setterDef
     }
@@ -363,8 +362,7 @@ trait MethodSynthesis {
           context.error(tree.pos, s"Internal error: Unable to find the synthetic factory method corresponding to implicit class $name in $enclClass / ${enclClass.info.decls}")
         result
       }
-      def derivedTree: DefDef          =
-        factoryMeth(mods & flagsMask | flagsExtra, name, tree)
+      def derivedTree: DefDef          = factoryMeth(derivedMods, name, tree)
       def flagsExtra: Long             = METHOD | IMPLICIT | SYNTHETIC
       def flagsMask: Long              = AccessFlags
       def name: TermName               = tree.name.toTermName
@@ -385,8 +383,9 @@ trait MethodSynthesis {
       }
     }
     case class Getter(tree: ValDef) extends BaseGetter(tree) {
-      override def derivedSym = if (mods.isDeferred) basisSym else basisSym.getterIn(enclClass)
-      private def derivedRhs  = if (mods.isDeferred) EmptyTree else fieldSelection
+      override def derivedSym = if (Field.noFieldFor(tree)) basisSym else basisSym.getterIn(enclClass)
+      private def derivedRhs  = if (Field.noFieldFor(tree)) tree.rhs else fieldSelection
+
       private def derivedTpt = {
         // For existentials, don't specify a type for the getter, even one derived
         // from the symbol! This leads to incompatible existentials for the field and
@@ -400,19 +399,21 @@ trait MethodSynthesis {
           // Range position errors ensue if we don't duplicate this in some
           // circumstances (at least: concrete vals with existential types.)
           case ExistentialType(_, _)  => TypeTree() setOriginal (tree.tpt.duplicate setPos tree.tpt.pos.focus)
-          case _ if mods.isDeferred   => TypeTree() setOriginal tree.tpt // keep type tree of original abstract field
+          case _ if isDeferred        => TypeTree() setOriginal tree.tpt // keep type tree of original abstract field
           case tp                     => TypeTree(tp)
         }
         tpt setPos tree.tpt.pos.focus
       }
       override def derivedTree: DefDef = newDefDef(derivedSym, derivedRhs)(tpt = derivedTpt)
     }
+
     /** Implements lazy value accessors:
-     *    - for lazy values of type Unit and all lazy fields inside traits,
-     *      the rhs is the initializer itself
-     *    - for all other lazy values z the accessor is a block of this form:
-     *      { z = <rhs>; z } where z can be an identifier or a field.
-     */
+      *    - for lazy values of type Unit and all lazy fields inside traits,
+      *      the rhs is the initializer itself, because we'll just "compute" the result on every access
+      *     ("computing" unit / constant type is free -- the side-effect is still only run once, using the init bitmap)
+      *    - for all other lazy values z the accessor is a block of this form:
+      *      { z = <rhs>; z } where z can be an identifier or a field.
+      */
     case class LazyValGetter(tree: ValDef) extends BaseGetter(tree) {
       class ChangeOwnerAndModuleClassTraverser(oldowner: Symbol, newowner: Symbol)
         extends ChangeOwnerTraverser(oldowner, newowner) {
@@ -432,10 +433,10 @@ trait MethodSynthesis {
       override def derivedTree: DefDef = {
         val ValDef(_, _, tpt0, rhs0) = tree
         val rhs1 = context.unit.transformed.getOrElse(rhs0, rhs0)
-        val body = (
-          if (tree.symbol.owner.isTrait || hasUnitType(basisSym)) rhs1
+        val body =
+          if (tree.symbol.owner.isTrait || Field.noFieldFor(tree)) rhs1 // TODO move tree.symbol.owner.isTrait into noFieldFor
           else gen.mkAssignAndReturn(basisSym, rhs1)
-        )
+
         derivedSym setPos tree.pos // cannot set it at createAndEnterSymbol because basisSym can possibly still have NoPosition
         val ddefRes = DefDef(derivedSym, new ChangeOwnerAndModuleClassTraverser(basisSym, derivedSym)(body))
         // ValDef will have its position focused whereas DefDef will have original correct rangepos
@@ -454,6 +455,24 @@ trait MethodSynthesis {
 
       override def derivedSym = basisSym.setterIn(enclClass)
     }
+
+    object Field {
+      // No field for these vals (either never emitted or eliminated later on):
+      //   - abstract vals have no value we could store (until they become concrete, potentially)
+      //   - lazy vals of type Unit
+      //   - [Emitted, later removed during AddInterfaces/Mixins] concrete vals in traits can't have a field
+      //   - [Emitted, later removed during Constructors] a concrete val with a statically known value (Unit / ConstantType)
+      //     performs its side effect according to lazy/strict semantics, but doesn't need to store its value
+      //     each access will "evaluate" the RHS (a literal) again
+      // We would like to avoid emitting unnecessary fields, but the required knowledge isn't available until after typer.
+      // The only way to avoid emitting & suppressing, is to not emit at all until we are sure to need the field, as dotty does.
+      // NOTE: do not look at `vd.symbol` when called from `enterGetterSetter` (luckily, that call-site implies `!mods.isLazy`),
+      // as the symbol info is in the process of being created then.
+      // TODO: harmonize tree & symbol creation
+      // TODO: the `def field` call-site does not tollerate including `|| vd.symbol.owner.isTrait` --> tests break
+      def noFieldFor(vd: ValDef) = vd.mods.isDeferred || (vd.mods.isLazy && isUnitType(vd.symbol.info)) // || vd.symbol.owner.isTrait))
+    }
+
     case class Field(tree: ValDef) extends DerivedFromValDef {
       def name       = tree.localName
       def category   = FieldTargetClass
@@ -462,11 +481,13 @@ trait MethodSynthesis {
       // By default annotations go to the field, except if the field is
       // generated for a class parameter (PARAMACCESSOR).
       override def keepClean = !mods.isParamAccessor
-      override def derivedTree = (
-        if (mods.isDeferred) EmptyTree
-        else if (mods.isLazy) copyValDef(tree)(mods = mods | flagsExtra, name = this.name, rhs = EmptyTree).setPos(tree.pos.focus)
+
+      // handle lazy val first for now (we emit a Field even though we probably shouldn't...)
+      override def derivedTree =
+        if (mods.isLazy) copyValDef(tree)(mods = mods | flagsExtra, name = this.name, rhs = EmptyTree).setPos(tree.pos.focus)
+        else if (Field.noFieldFor(tree)) EmptyTree
         else copyValDef(tree)(mods = mods | flagsExtra, name = this.name)
-      )
+
     }
     case class Param(tree: ValDef) extends DerivedFromValDef {
       def name       = tree.name
@@ -501,12 +522,12 @@ trait MethodSynthesis {
       // Derives a tree without attempting to use the original tree's symbol.
       override def derivedTree = {
         atPos(tree.pos.focus) {
-          DefDef(derivedMods, name, Nil, ListOfNil, tree.tpt.duplicate,
+          DefDef(derivedMods mapAnnotations (_ => Nil), name, Nil, ListOfNil, tree.tpt.duplicate,
             if (isDeferred) EmptyTree else Select(This(owner), tree.name)
           )
         }
       }
-      override def createAndEnterSymbol(): Symbol = enterSyntheticSym(derivedTree)
+      override def createAndEnterSymbol(): MethodSymbol = enterSyntheticSym(derivedTree).asInstanceOf[MethodSymbol]
     }
     case class BooleanBeanGetter(tree: ValDef) extends BeanAccessor("is") with AnyBeanGetter { }
     case class BeanGetter(tree: ValDef) extends BeanAccessor("get") with AnyBeanGetter { }
diff --git a/src/compiler/scala/tools/nsc/typechecker/Namers.scala b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
index 4ad81b60ae..254cb7111c 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Namers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
@@ -115,21 +115,14 @@ trait Namers extends MethodSynthesis {
         TypeSigError(tree, ex)
         alt
     }
-    // PRIVATE | LOCAL are fields generated for primary constructor arguments
-    // @PP: ...or fields declared as private[this].  PARAMACCESSOR marks constructor arguments.
-    // Neither gets accessors so the code is as far as I know still correct.
-    def noEnterGetterSetter(vd: ValDef) = !vd.mods.isLazy && (
-         !owner.isClass
-      || (vd.mods.isPrivateLocal && !vd.mods.isCaseAccessor)
-      || (vd.name startsWith nme.OUTER)
-      || (context.unit.isJava)
-      || isEnumConstant(vd)
-    )
 
-    def noFinishGetterSetter(vd: ValDef) = (
-         (vd.mods.isPrivateLocal && !vd.mods.isLazy) // all lazy vals need accessors, even private[this]
-      || vd.symbol.isModuleVar
-      || isEnumConstant(vd))
+    // All lazy vals need accessors, including those owned by terms (e.g., in method) or private[this] in a class
+    def deriveAccessors(vd: ValDef) = vd.mods.isLazy || (owner.isClass && deriveAccessorsInClass(vd))
+
+    private def deriveAccessorsInClass(vd: ValDef) =
+      !vd.mods.isPrivateLocal &&         // note, private[this] lazy vals do get accessors -- see outer disjunction of deriveAccessors
+      !(vd.name startsWith nme.OUTER) && // outer accessors are added later, in explicitouter
+      !isEnumConstant(vd)                // enums can only occur in classes, so only check here
 
     /** Determines whether this field holds an enum constant.
       * To qualify, the following conditions must be met:
@@ -655,11 +648,15 @@ trait Namers extends MethodSynthesis {
       }
     }
 
-    def enterValDef(tree: ValDef) {
-      if (noEnterGetterSetter(tree))
-        assignAndEnterFinishedSymbol(tree)
-      else
-        enterGetterSetter(tree)
+    def enterValDef(tree: ValDef): Unit = {
+      val isScala = !context.unit.isJava
+      if (isScala) {
+        if (nme.isSetterName(tree.name)) ValOrVarWithSetterSuffixError(tree)
+        if (tree.mods.isPrivateLocal && tree.mods.isCaseAccessor) PrivateThisCaseClassParameterError(tree)
+      }
+
+      if (isScala && deriveAccessors(tree)) enterGetterSetter(tree)
+      else assignAndEnterFinishedSymbol(tree)
 
       if (isEnumConstant(tree))
         tree.symbol setInfo ConstantType(Constant(tree.symbol))
diff --git a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
index 0198529ef7..7252cae0b5 100644
--- a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
@@ -1188,20 +1188,8 @@ abstract class RefChecks extends InfoTransform with scala.reflect.internal.trans
       // set NoType so it will be ignored.
       val cdef          = ClassDef(module.moduleClass, impl) setType NoType
 
-      // Create the module var unless the immediate owner is a class and
-      // the module var already exists there. See SI-5012, SI-6712.
-      def findOrCreateModuleVar() = {
-        val vsym = (
-          if (site.isTerm) NoSymbol
-          else site.info decl nme.moduleVarName(moduleName)
-        )
-        vsym orElse (site newModuleVarSymbol module)
-      }
       def newInnerObject() = {
-        // Create the module var unless it is already in the module owner's scope.
-        // The lookup is on module.enclClass and not module.owner lest there be a
-        // nullary method between us and the class; see SI-5012.
-        val moduleVar = findOrCreateModuleVar()
+        val moduleVar = site newModuleVarSymbol module
         val rhs       = gen.newModule(module, moduleVar.tpe)
         val body      = if (site.isTrait) rhs else gen.mkAssignAndReturn(moduleVar, rhs)
         val accessor  = DefDef(module, body.changeOwner(moduleVar -> module))
@@ -1217,6 +1205,7 @@ abstract class RefChecks extends InfoTransform with scala.reflect.internal.trans
       }
       val newTrees = cdef :: (
         if (module.isStatic)
+          // trait T { def f: Object }; object O extends T { object f }. Need to generate method f in O.
           if (module.isOverridingSymbol) matchingInnerObject() else Nil
         else
           newInnerObject()
@@ -1468,10 +1457,13 @@ abstract class RefChecks extends InfoTransform with scala.reflect.internal.trans
         case m: MemberDef =>
           val sym = m.symbol
           applyChecks(sym.annotations)
-          // validate implicitNotFoundMessage
-          analyzer.ImplicitNotFoundMsg.check(sym) foreach { warn =>
-            reporter.warning(tree.pos, f"Invalid implicitNotFound message for ${sym}%s${sym.locationString}%s:%n$warn")
-          }
+
+          def messageWarning(name: String)(warn: String) =
+            reporter.warning(tree.pos, f"Invalid $name message for ${sym}%s${sym.locationString}%s:%n$warn")
+
+          // validate implicitNotFoundMessage and implicitAmbiguousMessage
+          analyzer.ImplicitNotFoundMsg.check(sym) foreach messageWarning("implicitNotFound")
+          analyzer.ImplicitAmbiguousMsg.check(sym) foreach messageWarning("implicitAmbiguous")
 
         case tpt@TypeTree() =>
           if(tpt.original != null) {
@@ -1511,7 +1503,8 @@ abstract class RefChecks extends InfoTransform with scala.reflect.internal.trans
         sym.isSourceMethod &&
         sym.isCase &&
         sym.name == nme.apply &&
-        isClassTypeAccessible(tree)
+        isClassTypeAccessible(tree) &&
+        !tree.tpe.resultType.typeSymbol.primaryConstructor.isLessAccessibleThan(tree.symbol)
 
       if (doTransform) {
         tree foreach {
diff --git a/src/compiler/scala/tools/nsc/typechecker/StdAttachments.scala b/src/compiler/scala/tools/nsc/typechecker/StdAttachments.scala
index ea44b9dc39..92b0719ba3 100644
--- a/src/compiler/scala/tools/nsc/typechecker/StdAttachments.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/StdAttachments.scala
@@ -132,7 +132,7 @@ trait StdAttachments {
   /** Marks the tree as a macro impl reference, which is a naked reference to a method.
    *
    *  This is necessary for typechecking macro impl references (see `DefaultMacroCompiler.defaultResolveMacroImpl`),
-   *  because otherwise typing a naked reference will result in the "follow this method with `_' if you want to
+   *  because otherwise typing a naked reference will result in the "follow this method with `_` if you want to
    *  treat it as a partially applied function" errors.
    *
    *  This mark suppresses adapt except for when the annottee is a macro application.
diff --git a/src/compiler/scala/tools/nsc/typechecker/SyntheticMethods.scala b/src/compiler/scala/tools/nsc/typechecker/SyntheticMethods.scala
index d65d2092ad..4ccc183334 100644
--- a/src/compiler/scala/tools/nsc/typechecker/SyntheticMethods.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/SyntheticMethods.scala
@@ -304,6 +304,7 @@ trait SyntheticMethods extends ast.TreeDSL {
          clazz.isModuleClass
       && clazz.isSerializable
       && !hasConcreteImpl(nme.readResolve)
+      && clazz.isStatic
     )
 
     def synthesize(): List[Tree] = {
@@ -335,16 +336,18 @@ trait SyntheticMethods extends ast.TreeDSL {
         }
         for ((m, impl) <- methods ; if shouldGenerate(m)) yield impl()
       }
-      def extras = (
+      def extras = {
         if (needsReadResolve) {
           // Aha, I finally decoded the original comment.
           // This method should be generated as private, but apparently if it is, then
           // it is name mangled afterward.  (Wonder why that is.) So it's only protected.
           // For sure special methods like "readResolve" should not be mangled.
-          List(createMethod(nme.readResolve, Nil, ObjectTpe)(m => { m setFlag PRIVATE ; REF(clazz.sourceModule) }))
+          List(createMethod(nme.readResolve, Nil, ObjectTpe)(m => {
+            m setFlag PRIVATE; REF(clazz.sourceModule)
+          }))
         }
         else Nil
-      )
+      }
 
       try impls ++ extras
       catch { case _: TypeError if reporter.hasErrors => Nil }
diff --git a/src/compiler/scala/tools/nsc/typechecker/Tags.scala b/src/compiler/scala/tools/nsc/typechecker/Tags.scala
index 57dc74d2a0..56127f4026 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Tags.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Tags.scala
@@ -36,7 +36,7 @@ trait Tags {
      *  @param   allowMaterialization   If true (default) then the resolver is allowed to launch materialization macros when there's no class tag in scope.
      *                                  If false then materialization macros are prohibited from running.
      *
-     *  @returns Tree that represents an `scala.reflect.ClassTag` for `tp` if everything is okay.
+     *  @return  Tree that represents an `scala.reflect.ClassTag` for `tp` if everything is okay.
      *           EmptyTree if the result contains unresolved (i.e. not spliced) type parameters and abstract type members.
      *           EmptyTree if `allowMaterialization` is false, and there is no class tag in scope.
      */
@@ -57,7 +57,7 @@ trait Tags {
      *  @param   allowMaterialization   If true (default) then the resolver is allowed to launch materialization macros when there's no type tag in scope.
      *                                  If false then materialization macros are prohibited from running.
      *
-     *  @returns Tree that represents a `scala.reflect.TypeTag` for `tp` if everything is okay.
+     *  @return  Tree that represents a `scala.reflect.TypeTag` for `tp` if everything is okay.
      *           EmptyTree if `concrete` is true and the result contains unresolved (i.e. not spliced) type parameters and abstract type members.
      *           EmptyTree if `allowMaterialization` is false, and there is no array tag in scope.
      */
diff --git a/src/compiler/scala/tools/nsc/typechecker/TreeCheckers.scala b/src/compiler/scala/tools/nsc/typechecker/TreeCheckers.scala
index a7d48ceb89..e8db8309f1 100644
--- a/src/compiler/scala/tools/nsc/typechecker/TreeCheckers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/TreeCheckers.scala
@@ -262,7 +262,14 @@ abstract class TreeCheckers extends Analyzer {
         checkedTyped(tree, mode, pt)
     )
     private def checkedTyped(tree: Tree, mode: Mode, pt: Type): Tree = {
-      val typed = wrap(tree)(super.typed(tree, mode, pt))
+      val typed = wrap(tree)(super.typed(tree.clearType(), mode, pt))
+
+      // Vlad: super.typed returns null for package defs, why is that?
+      if (typed eq null)
+        return tree
+
+      if (typed.tpe ne null)
+        assert(!typed.tpe.isErroneous, "Tree has erroneous type: " + typed)
 
       if (tree ne typed)
         treesDiffer(tree, typed)
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index cc15a2485f..f26baf7d93 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -2714,7 +2714,7 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
      *
      * If 'T' is not fully defined, it is inferred by type checking
      * `apply$body` without a result type before type checking the block.
-     * The method's inferred result type is used instead of T`. [See test/files/pos/sammy_poly.scala]
+     * The method's inferred result type is used instead of `T`. [See test/files/pos/sammy_poly.scala]
      *
      * The `apply` method is identified by the argument `sam`; `S` corresponds to the argument `samClassTp`,
      * and `resPt` is derived from `samClassTp` -- it may be fully defined, or not...
@@ -3294,7 +3294,7 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
           // https://docs.oracle.com/javase/specs/jls/se8/html/jls-15.html#jls-15.12.3
           //
           // One can think of these methods as being infinitely overloaded. We create
-          // a ficticious new cloned method symbol for each call site that takes on a signature
+          // a fictitious new cloned method symbol for each call site that takes on a signature
           // governed by a) the argument types and b) the expected type
           val args1 = typedArgs(args, forArgMode(fun, mode))
           val pts = args1.map(_.tpe.deconst)
@@ -4095,7 +4095,7 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
 
         def resultingTypeTree(tpe: Type) = {
           // we need symbol-ful originals for reification
-          // hence we go the extra mile to hand-craft tis guy
+          // hence we go the extra mile to hand-craft this guy
           val original = arg1 match {
             case tt @ TypeTree() if tt.original != null => Annotated(ann, tt.original)
             // this clause is needed to correctly compile stuff like "new C @D" or "@(inline @getter)"
@@ -4247,7 +4247,7 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
         // in the special (though common) case where the types are equal, it pays to pack before comparing
         // especially virtpatmat needs more aggressive unification of skolemized types
         // this breaks src/library/scala/collection/immutable/TrieIterator.scala
-        // annotated types need to be lubbed regardless (at least, continations break if you by pass them like this)
+        // annotated types need to be lubbed regardless (at least, continuations break if you bypass them like this)
         def samePackedTypes = (
              !isPastTyper
           && thenp1.tpe.annotations.isEmpty
diff --git a/src/compiler/scala/tools/nsc/typechecker/TypersTracking.scala b/src/compiler/scala/tools/nsc/typechecker/TypersTracking.scala
index 550fd4e68d..37fbb73b85 100644
--- a/src/compiler/scala/tools/nsc/typechecker/TypersTracking.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/TypersTracking.scala
@@ -159,7 +159,7 @@ trait TypersTracking {
   // Some trees which are typed with mind-numbing frequency and
   // which add nothing by being printed. Did () type to Unit? Let's
   // gamble on yes.
-  private def printingOk(t: Tree) = printTypings && (settings.debug.value || !noPrint(t))
+  def printingOk(t: Tree) = printTypings && (settings.debug.value || !noPrint(t))
   def noPrintTyping(t: Tree) = (t.tpe ne null) || !printingOk(t)
   def noPrintAdapt(tree1: Tree, tree2: Tree) = !printingOk(tree1) || (
        (tree1.tpe == tree2.tpe)
diff --git a/src/compiler/scala/tools/nsc/util/ClassPath.scala b/src/compiler/scala/tools/nsc/util/ClassPath.scala
index 8d4d07759f..2811520b67 100644
--- a/src/compiler/scala/tools/nsc/util/ClassPath.scala
+++ b/src/compiler/scala/tools/nsc/util/ClassPath.scala
@@ -22,7 +22,7 @@ import Jar.isJarOrZip
 
 /** <p>
  *    This module provides star expansion of '-classpath' option arguments, behaves the same as
- *    java, see [http://java.sun.com/javase/6/docs/technotes/tools/windows/classpath.html]
+ *    java, see [[http://docs.oracle.com/javase/6/docs/technotes/tools/windows/classpath.html]]
  *  </p>
  *
  *  @author Stepan Koltsov
diff --git a/src/compiler/scala/tools/nsc/util/DocStrings.scala b/src/compiler/scala/tools/nsc/util/DocStrings.scala
index 4ff7067a21..501546b8f6 100755
--- a/src/compiler/scala/tools/nsc/util/DocStrings.scala
+++ b/src/compiler/scala/tools/nsc/util/DocStrings.scala
@@ -37,7 +37,7 @@ object DocStrings {
   /** Returns index of string `str` after `start` skipping longest
    *  sequence of space and tab characters, possibly also containing
    *  a single `*` character or the `/``**` sequence.
-   *  @pre  start == str.length || str(start) == `\n'
+   *  @pre  start == str.length || str(start) == `\n`
    */
   def skipLineLead(str: String, start: Int): Int =
     if (start == str.length) start
@@ -49,7 +49,7 @@ object DocStrings {
       else idx
     }
 
-  /** Skips to next occurrence of `\n' or to the position after the `/``**` sequence following index `start`.
+  /** Skips to next occurrence of `\n` or to the position after the `/``**` sequence following index `start`.
    */
   def skipToEol(str: String, start: Int): Int =
     if (start + 2 < str.length && (str charAt start) == '/' && (str charAt (start + 1)) == '*' && (str charAt (start + 2)) == '*') start + 3
diff --git a/src/compiler/scala/tools/reflect/ReflectGlobal.scala b/src/compiler/scala/tools/reflect/ReflectGlobal.scala
index ac63232967..e30d1ed7cd 100644
--- a/src/compiler/scala/tools/reflect/ReflectGlobal.scala
+++ b/src/compiler/scala/tools/reflect/ReflectGlobal.scala
@@ -1,9 +1,11 @@
 package scala.tools
 package reflect
 
+import scala.reflect.internal.util.ScalaClassLoader
 import scala.tools.nsc.Global
 import scala.tools.nsc.reporters.Reporter
 import scala.tools.nsc.Settings
+import scala.tools.nsc.typechecker.Analyzer
 
 /** A version of Global that uses reflection to get class
  *  infos, instead of reading class or source files.
@@ -11,6 +13,20 @@ import scala.tools.nsc.Settings
 class ReflectGlobal(currentSettings: Settings, reporter: Reporter, override val rootClassLoader: ClassLoader)
   extends Global(currentSettings, reporter) with scala.tools.reflect.ReflectSetup with scala.reflect.runtime.SymbolTable {
 
+  override lazy val analyzer = new {
+    val global: ReflectGlobal.this.type = ReflectGlobal.this
+  } with Analyzer {
+    /** Obtains the classLoader used for runtime macro expansion.
+     *
+     *  Macro expansion can use everything available in [[global.classPath]] or [[rootClassLoader]].
+     *  The [[rootClassLoader]] is used to obtain runtime defined macros.
+     */
+    override protected def findMacroClassLoader(): ClassLoader = {
+      val classpath = global.classPath.asURLs
+      ScalaClassLoader.fromURLs(classpath, rootClassLoader)
+    }
+  }
+
   override def transformedType(sym: Symbol) =
     postErasure.transformInfo(sym,
       erasure.transformInfo(sym,
diff --git a/src/library-aux/scala/Any.scala b/src/library-aux/scala/Any.scala
index 1be186d114..8caf0c5c0e 100644
--- a/src/library-aux/scala/Any.scala
+++ b/src/library-aux/scala/Any.scala
@@ -27,7 +27,7 @@ package scala
  *     w.print()
  * }}}
  *
- * See the [[http://docs.scala-lang.org/sips/pending/value-classes.html value classes guide]] for more
+ * See the [[http://docs.scala-lang.org/sips/completed/value-classes.html value classes guide]] for more
  * details on the interplay of universal traits and value classes.
  */
 abstract class Any {
diff --git a/src/library/scala/AnyVal.scala b/src/library/scala/AnyVal.scala
index ff62948413..fb3d213e19 100644
--- a/src/library/scala/AnyVal.scala
+++ b/src/library/scala/AnyVal.scala
@@ -49,7 +49,7 @@ package scala
  * It's important to note that user-defined value classes are limited, and in some circumstances,
  * still must allocate a value class instance at runtime. These limitations and circumstances are
  * explained in greater detail in the [[http://docs.scala-lang.org/overviews/core/value-classes.html Value Classes Guide]]
- * as well as in [[http://docs.scala-lang.org/sips/pending/value-classes.html SIP-15: Value Classes]],
+ * as well as in [[http://docs.scala-lang.org/sips/completed/value-classes.html SIP-15: Value Classes]],
  * the Scala Improvement Proposal.
  */
 abstract class AnyVal extends Any {
diff --git a/src/library/scala/Equals.scala b/src/library/scala/Equals.scala
index f2f9ead44c..e06557ccdd 100644
--- a/src/library/scala/Equals.scala
+++ b/src/library/scala/Equals.scala
@@ -13,8 +13,9 @@ package scala
  */
 trait Equals extends Any {
   /** A method that should be called from every well-designed equals method
-   *  that is open to be overridden in a subclass. See Programming in Scala,
-   *  Chapter 28 for discussion and design.
+   *  that is open to be overridden in a subclass. See
+   *  [[http://www.artima.com/pins1ed/object-equality.html Programming in Scala,
+   *  Chapter 28]] for discussion and design.
    *
    *  @param    that    the value being probed for possible equality
    *  @return   true if this instance can possibly equal `that`, otherwise false
diff --git a/src/library/scala/Option.scala b/src/library/scala/Option.scala
index f134f5ce3d..7282feebb6 100644
--- a/src/library/scala/Option.scala
+++ b/src/library/scala/Option.scala
@@ -270,7 +270,7 @@ sealed abstract class Option[+A] extends Product with Serializable {
    *  // Returns None because the partial function doesn't cover the case.
    *  Some("ftp") collect {case "http" => "HTTP"}
    *
-   *  // Returns None because None is passed to the collect method.
+   *  // Returns None because the option is empty. There is no value to pass to the partial function.
    *  None collect {case value => value}
    *  }}}
    *
diff --git a/src/library/scala/Predef.scala b/src/library/scala/Predef.scala
index fa58015a84..334377e838 100644
--- a/src/library/scala/Predef.scala
+++ b/src/library/scala/Predef.scala
@@ -56,7 +56,7 @@ import scala.io.StdIn
  *  only contain natural numbers (i.e. non-negative), and that the result returned
  *  will also be natural. `require` is distinct from `assert` in that if the
  *  condition fails, then the caller of the function is to blame rather than a
- *  logical error having been made within `addNaturals` itself. `ensures` is a
+ *  logical error having been made within `addNaturals` itself. `ensuring` is a
  *  form of `assert` that declares the guarantee the function is providing with
  *  regards to its return value.
  *
diff --git a/src/library/scala/annotation/implicitAmbiguous.scala b/src/library/scala/annotation/implicitAmbiguous.scala
new file mode 100644
index 0000000000..46eab9ae8f
--- /dev/null
+++ b/src/library/scala/annotation/implicitAmbiguous.scala
@@ -0,0 +1,34 @@
+package scala.annotation
+
+import scala.annotation.meta._
+
+/**
+  * To customize the error message that's emitted when an implicit of type
+  * C[T1,..., TN] is found more than once, annotate the class C
+  * with @implicitAmbiguous. Assuming C has type parameters X1,..., XN, the
+  * error message will be the result of replacing all occurrences of ${Xi} in
+  * the string msg with the string representation of the corresponding type
+  * argument Ti. *
+  *
+  * If more than one @implicitAmbiguous annotation is collected, the compiler is
+  * free to pick any of them to display.
+  *
+  * Nice errors can direct users to fix imports or even tell them why code
+  * intentionally doesn't compile.
+  *
+  * {{{
+  * trait =!=[C, D]
+  *
+  * implicit def neq[E, F] : E =!= F = null
+  *
+  * @annotation.implicitAmbiguous("Could not prove ${J} =!= ${J}")
+  * implicit def neqAmbig1[G, H, J] : J =!= J = null
+  * implicit def neqAmbig2[I] : I =!= I = null
+  *
+  * implicitly[Int =!= Int]
+  * }}}
+  *
+  * @author Brian McKenna
+  * @since 2.12.0
+  */
+final class implicitAmbiguous(msg: String) extends scala.annotation.StaticAnnotation {}
diff --git a/src/library/scala/collection/immutable/HashSet.scala b/src/library/scala/collection/immutable/HashSet.scala
index 49b4397cf2..603d97c3ad 100644
--- a/src/library/scala/collection/immutable/HashSet.scala
+++ b/src/library/scala/collection/immutable/HashSet.scala
@@ -162,13 +162,6 @@ class HashSet[A] extends AbstractSet[A]
   def - (e: A): HashSet[A] =
     nullToEmpty(removed0(e, computeHash(e), 0))
 
-  /** Returns this $coll as an immutable set.
-   *  
-   *  A new set will not be built; lazy collections will stay lazy.
-   */
-  @deprecatedOverriding("Immutable sets should do nothing on toSet but return themselves cast as a Set.", "2.11.0")
-  override def toSet[B >: A]: Set[B] = this.asInstanceOf[Set[B]]
-
   override def filter(p: A => Boolean) = {
     val buffer = new Array[HashSet[A]](bufferSize(size))
     nullToEmpty(filter0(p, false, 0, buffer, 0))
@@ -201,6 +194,7 @@ class HashSet[A] extends AbstractSet[A]
 
   protected def writeReplace(): AnyRef = new HashSet.SerializationProxy(this)
 
+  override def toSet[B >: A]: Set[B] = this.asInstanceOf[HashSet[B]]
 }
 
 /** $factoryInfo
diff --git a/src/library/scala/collection/immutable/ListSet.scala b/src/library/scala/collection/immutable/ListSet.scala
index a6e6fba0a5..adc975479a 100644
--- a/src/library/scala/collection/immutable/ListSet.scala
+++ b/src/library/scala/collection/immutable/ListSet.scala
@@ -138,13 +138,6 @@ class ListSet[A] extends AbstractSet[A]
 
   override def stringPrefix = "ListSet"
 
-  /** Returns this $coll as an immutable set.
-   *  
-   *  A new set will not be built; lazy collections will stay lazy.
-   */
-  @deprecatedOverriding("Immutable sets should do nothing on toSet but return themselves cast as a Set.", "2.11.0")
-  override def toSet[B >: A]: Set[B] = this.asInstanceOf[Set[B]]
-
   /** Represents an entry in the `ListSet`.
    */
   protected class Node(override val head: A) extends ListSet[A] with Serializable {
@@ -186,4 +179,6 @@ class ListSet[A] extends AbstractSet[A]
 
     override def tail: ListSet[A] = self
   }
+  
+  override def toSet[B >: A]: Set[B] = this.asInstanceOf[ListSet[B]]
 }
diff --git a/src/library/scala/collection/immutable/MapLike.scala b/src/library/scala/collection/immutable/MapLike.scala
index 94a5b7929a..bd5b9c9faf 100644
--- a/src/library/scala/collection/immutable/MapLike.scala
+++ b/src/library/scala/collection/immutable/MapLike.scala
@@ -113,6 +113,11 @@ self =>
     override def - (elem: A): immutable.Set[A] =
       if (this(elem)) immutable.Set[A]() ++ this - elem
       else this
+      
+    // ImmutableDefaultKeySet is only protected, so we won't warn on override.
+    // Someone could override in a way that makes widening not okay
+    // (e.g. by overriding +, though the version in this class is fine)
+    override def toSet[B >: A]: Set[B] = this.asInstanceOf[Set[B]]
   }
 
   /** This function transforms all the values of mappings contained
diff --git a/src/library/scala/collection/immutable/Set.scala b/src/library/scala/collection/immutable/Set.scala
index 7725ad9ee3..a115469b83 100644
--- a/src/library/scala/collection/immutable/Set.scala
+++ b/src/library/scala/collection/immutable/Set.scala
@@ -35,7 +35,22 @@ trait Set[A] extends Iterable[A]
   override def companion: GenericCompanion[Set] = Set
   
   
-  override def toSet[B >: A]: Set[B] = to[({type l[a] = immutable.Set[B]})#l] // for bincompat; remove in dev
+  /** Returns this $coll as an immutable set, perhaps accepting a
+   *  wider range of elements.  Since it already is an
+   *  immutable set, it will only be rebuilt if the underlying structure
+   *  cannot be expanded to include arbitrary element types.
+   *  For instance, `BitSet` and `SortedSet` will be rebuilt, as
+   *  they require `Int` and sortable elements respectively.
+   *
+   *  When in doubt, the set will be rebuilt.  Rebuilt sets never
+   *  need to be rebuilt again.
+   */
+  override def toSet[B >: A]: Set[B] = {
+      // This way of building sets typically has the best benchmarks, surprisingly!
+    val sb = Set.newBuilder[B]
+    foreach(sb += _)
+    sb.result()
+  }
   
   override def seq: Set[A] = this
   protected override def parCombiner = ParSet.newCombiner[A] // if `immutable.SetLike` gets introduced, please move this there!
@@ -88,8 +103,10 @@ object Set extends ImmutableSetFactory[Set] {
       if (f(elem1)) Some(elem1)
       else None
     }
-    @deprecatedOverriding("Immutable sets should do nothing on toSet but return themselves cast as a Set.", "2.11.0")
-    override def toSet[B >: A]: Set[B] = this.asInstanceOf[Set[B]]
+    // Why is Set1 non-final?  Need to fix that!
+    @deprecatedOverriding("This immutable set should do nothing on toSet but cast itself to a Set with a wider element type.", "2.11.8")
+    override def toSet[B >: A]: Set[B] = this.asInstanceOf[Set1[B]]
+
   }
 
   /** An optimized representation for immutable sets of size 2 */
@@ -121,8 +138,9 @@ object Set extends ImmutableSetFactory[Set] {
       else if (f(elem2)) Some(elem2)
       else None
     }
-    @deprecatedOverriding("Immutable sets should do nothing on toSet but return themselves cast as a Set.", "2.11.0")
-    override def toSet[B >: A]: Set[B] = this.asInstanceOf[Set[B]]
+    // Why is Set2 non-final?  Need to fix that!
+    @deprecatedOverriding("This immutable set should do nothing on toSet but cast itself to a Set with a wider element type.", "2.11.8")
+    override def toSet[B >: A]: Set[B] = this.asInstanceOf[Set2[B]]
   }
 
   /** An optimized representation for immutable sets of size 3 */
@@ -156,8 +174,9 @@ object Set extends ImmutableSetFactory[Set] {
       else if (f(elem3)) Some(elem3)
       else None
     }
-    @deprecatedOverriding("Immutable sets should do nothing on toSet but return themselves cast as a Set.", "2.11.0")
-    override def toSet[B >: A]: Set[B] = this.asInstanceOf[Set[B]]
+    // Why is Set3 non-final?  Need to fix that!
+    @deprecatedOverriding("This immutable set should do nothing on toSet but cast itself to a Set with a wider element type.", "2.11.8")
+    override def toSet[B >: A]: Set[B] = this.asInstanceOf[Set3[B]]
   }
 
   /** An optimized representation for immutable sets of size 4 */
@@ -193,8 +212,9 @@ object Set extends ImmutableSetFactory[Set] {
       else if (f(elem4)) Some(elem4)
       else None
     }
-    @deprecatedOverriding("Immutable sets should do nothing on toSet but return themselves cast as a Set.", "2.11.0")
-    override def toSet[B >: A]: Set[B] = this.asInstanceOf[Set[B]]
+    // Why is Set4 non-final?  Need to fix that!
+    @deprecatedOverriding("This immutable set should do nothing on toSet but cast itself to a Set with a wider element type.", "2.11.8")
+    override def toSet[B >: A]: Set[B] = this.asInstanceOf[Set4[B]]
   }
 }
 
diff --git a/src/library/scala/collection/immutable/SortedMap.scala b/src/library/scala/collection/immutable/SortedMap.scala
index f1493551ab..682788e18e 100644
--- a/src/library/scala/collection/immutable/SortedMap.scala
+++ b/src/library/scala/collection/immutable/SortedMap.scala
@@ -53,6 +53,12 @@ self =>
       val map = self.rangeImpl(from, until)
       new map.DefaultKeySortedSet
     }
+    override def toSet[C >: A]: Set[C] = {
+      // This way of building sets typically has the best benchmarks, surprisingly!
+      val sb = Set.newBuilder[C]
+      foreach(sb += _)
+      sb.result()
+    }
   }
 
   /** Add a key/value pair to this map.
diff --git a/src/library/scala/collection/mutable/AVLTree.scala b/src/library/scala/collection/mutable/AVLTree.scala
deleted file mode 100644
index b63d0aae33..0000000000
--- a/src/library/scala/collection/mutable/AVLTree.scala
+++ /dev/null
@@ -1,250 +0,0 @@
-/*                     __                                               *\
-**     ________ ___   / /  ___     Scala API                            **
-**    / __/ __// _ | / /  / _ |    (c) 2003-2013, LAMP/EPFL             **
-**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
-** /____/\___/_/ |_/____/_/ | |                                         **
-**                          |/                                          **
-\*                                                                      */
-
-package scala
-package collection
-package mutable
-
-/**
- * An immutable AVL Tree implementation formerly used by mutable.TreeSet
- *
- * @author Lucien Pereira
- */
-@deprecated("AVLTree and its related classes are being removed from the standard library since they're not different enough from RedBlackTree to justify keeping them.", "2.11.2")
-private[mutable] sealed trait AVLTree[+A] extends Serializable {
-  def balance: Int
-
-  def depth: Int
-
-  def iterator[B >: A]: Iterator[B] = Iterator.empty
-
-  def contains[B >: A](value: B, ordering: Ordering[B]): Boolean = false
-
-  /**
-   * Returns a new tree containing the given element.
-   * Throws an IllegalArgumentException if element is already present.
-   *
-   */
-  def insert[B >: A](value: B, ordering: Ordering[B]): AVLTree[B] = Node(value, Leaf, Leaf)
-
-  /**
-   * Return a new tree which not contains given element.
-   *
-   */
-  def remove[B >: A](value: B, ordering: Ordering[B]): AVLTree[A] =
-    throw new NoSuchElementException(String.valueOf(value))
-
-  /**
-   * Return a tuple containing the smallest element of the provided tree
-   * and a new tree from which this element has been extracted.
-   *
-   */
-  def removeMin[B >: A]: (B, AVLTree[B]) = sys.error("Should not happen.")
-
-  /**
-   * Return a tuple containing the biggest element of the provided tree
-   * and a new tree from which this element has been extracted.
-   *
-   */
-  def removeMax[B >: A]: (B, AVLTree[B]) = sys.error("Should not happen.")
-
-  def rebalance[B >: A]: AVLTree[B] = this
-
-  def leftRotation[B >: A]: Node[B] = sys.error("Should not happen.")
-
-  def rightRotation[B >: A]: Node[B] = sys.error("Should not happen.")
-
-  def doubleLeftRotation[B >: A]: Node[B] = sys.error("Should not happen.")
-
-  def doubleRightRotation[B >: A]: Node[B] = sys.error("Should not happen.")
-}
-
-/**
- * @deprecated("AVLTree and its related classes are being removed from the standard library since they're not different enough from RedBlackTree to justify keeping them.", "2.11.0")
- */
-private case object Leaf extends AVLTree[Nothing] {
-  override val balance: Int = 0
-
-  override val depth: Int = -1
-}
-
-/**
- * @deprecated("AVLTree and its related classes are being removed from the standard library since they're not different enough from RedBlackTree to justify keeping them.", "2.11.0")
- */
-private case class Node[A](data: A, left: AVLTree[A], right: AVLTree[A]) extends AVLTree[A] {
-  override val balance: Int = right.depth - left.depth
-
-  override val depth: Int = math.max(left.depth, right.depth) + 1
-
-  override def iterator[B >: A]: Iterator[B] = new AVLIterator(this)
-
-  override def contains[B >: A](value: B, ordering: Ordering[B]) = {
-    val ord = ordering.compare(value, data)
-    if (0 == ord)
-      true
-    else if (ord < 0)
-      left.contains(value, ordering)
-    else
-      right.contains(value, ordering)
-  }
-
-  /**
-   * Returns a new tree containing the given element.
-   * Throws an IllegalArgumentException if element is already present.
-   *
-   */
-  override def insert[B >: A](value: B, ordering: Ordering[B]) = {
-    val ord = ordering.compare(value, data)
-    if (0 == ord)
-      throw new IllegalArgumentException()
-    else if (ord < 0)
-      Node(data, left.insert(value, ordering), right).rebalance
-    else
-      Node(data, left, right.insert(value, ordering)).rebalance
-  }
-
-  /**
-   * Return a new tree which not contains given element.
-   *
-   */
-  override def remove[B >: A](value: B, ordering: Ordering[B]): AVLTree[A] = {
-    val ord = ordering.compare(value, data)
-    if(ord == 0) {
-      if (Leaf == left) {
-        if (Leaf == right) {
-          Leaf
-        } else {
-          val (min, newRight) = right.removeMin
-          Node(min, left, newRight).rebalance
-        }
-      } else {
-        val (max, newLeft) = left.removeMax
-        Node(max, newLeft, right).rebalance
-      }
-    } else if (ord < 0) {
-      Node(data, left.remove(value, ordering), right).rebalance
-    } else {
-      Node(data, left, right.remove(value, ordering)).rebalance
-    }
-  }
-
-  /**
-   * Return a tuple containing the smallest element of the provided tree
-   * and a new tree from which this element has been extracted.
-   *
-   */
-  override def removeMin[B >: A]: (B, AVLTree[B]) = {
-    if (Leaf == left)
-      (data, right)
-    else {
-      val (min, newLeft) = left.removeMin
-      (min, Node(data, newLeft, right).rebalance)
-    }
-  }
-
-  /**
-   * Return a tuple containing the biggest element of the provided tree
-   * and a new tree from which this element has been extracted.
-   *
-   */
-  override def removeMax[B >: A]: (B, AVLTree[B]) = {
-    if (Leaf == right)
-      (data, left)
-    else {
-      val (max, newRight) = right.removeMax
-      (max, Node(data, left, newRight).rebalance)
-    }
-  }
-
-  override def rebalance[B >: A] = {
-    if (-2 == balance) {
-      if (1 == left.balance)
-        doubleRightRotation
-      else
-        rightRotation
-    } else if (2 == balance) {
-      if (-1 == right.balance)
-        doubleLeftRotation
-      else
-        leftRotation
-    } else {
-      this
-    }
-  }
-
-  override def leftRotation[B >: A] = {
-    if (Leaf != right) {
-      val r: Node[A] = right.asInstanceOf[Node[A]]
-      Node(r.data, Node(data, left, r.left), r.right)
-    } else sys.error("Should not happen.")
-  }
-
-  override def rightRotation[B >: A] = {
-    if (Leaf != left) {
-      val l: Node[A] = left.asInstanceOf[Node[A]]
-      Node(l.data, l.left, Node(data, l.right, right))
-    } else sys.error("Should not happen.")
-  }
-
-  override def doubleLeftRotation[B >: A] = {
-    if (Leaf != right) {
-      val r: Node[A] = right.asInstanceOf[Node[A]]
-      // Let's save an instanceOf by 'inlining' the left rotation
-      val rightRotated = r.rightRotation
-      Node(rightRotated.data, Node(data, left, rightRotated.left), rightRotated.right)
-    } else sys.error("Should not happen.")
-  }
-
-  override def doubleRightRotation[B >: A] = {
-    if (Leaf != left) {
-      val l: Node[A] = left.asInstanceOf[Node[A]]
-      // Let's save an instanceOf by 'inlining' the right rotation
-      val leftRotated = l.leftRotation
-      Node(leftRotated.data, leftRotated.left, Node(data, leftRotated.right, right))
-    } else sys.error("Should not happen.")
-  }
-}
-
-/**
- * @deprecated("AVLTree and its related classes are being removed from the standard library since they're not different enough from RedBlackTree to justify keeping them.", "2.11.0")
- */
-private class AVLIterator[A](root: Node[A]) extends Iterator[A] {
-  val stack = mutable.ArrayStack[Node[A]](root)
-  diveLeft()
-
-  private def diveLeft(): Unit = {
-    if (Leaf != stack.head.left) {
-      val left: Node[A] = stack.head.left.asInstanceOf[Node[A]]
-      stack.push(left)
-      diveLeft()
-    }
-  }
-
-  private def engageRight(): Unit = {
-    if (Leaf != stack.head.right) {
-      val right: Node[A] = stack.head.right.asInstanceOf[Node[A]]
-      stack.pop()
-      stack.push(right)
-      diveLeft()
-    } else
-      stack.pop()
-  }
-
-  override def hasNext: Boolean = !stack.isEmpty
-
-  override def next(): A = {
-    if (stack.isEmpty)
-      throw new NoSuchElementException()
-    else {
-      val result = stack.head.data
-      // Let's maintain stack for the next invocation
-      engageRight()
-      result
-    }
-  }
-}
diff --git a/src/library/scala/collection/mutable/PriorityQueue.scala b/src/library/scala/collection/mutable/PriorityQueue.scala
index 619beeb1d6..e6889da3b5 100644
--- a/src/library/scala/collection/mutable/PriorityQueue.scala
+++ b/src/library/scala/collection/mutable/PriorityQueue.scala
@@ -18,8 +18,19 @@ import generic._
  *
  *  Only the `dequeue` and `dequeueAll` methods will return elements in priority
  *  order (while removing elements from the heap).  Standard collection methods
- *  including `drop` and `iterator` will remove or traverse the heap in whichever
- *  order seems most convenient.
+ *  including `drop`, `iterator`, and `toString` will remove or traverse the heap
+ *  in whichever order seems most convenient.
+ *
+ *  Therefore, printing a `PriorityQueue` will not reveal the priority order of
+ *  the elements, though the highest-priority element will be printed first.  To
+ *  print the elements in order, one must duplicate the `PriorityQueue` (by using
+ *  `clone`, for instance) and then dequeue them:
+ *
+ *  @example {{{
+ *  val pq = collection.mutable.PriorityQueue(1, 2, 5, 3, 7)
+ *  println(pq)                  // elements probably not in order
+ *  println(pq.clone.dequeueAll) // prints Vector(7, 5, 3, 2, 1)
+ *  }}}
  *
  *  @tparam A    type of the elements in this priority queue.
  *  @param ord   implicit ordering used to compare the elements of type `A`.
diff --git a/src/library/scala/concurrent/SyncVar.scala b/src/library/scala/concurrent/SyncVar.scala
index 9634f6d900..1ee27b0f36 100644
--- a/src/library/scala/concurrent/SyncVar.scala
+++ b/src/library/scala/concurrent/SyncVar.scala
@@ -40,7 +40,7 @@ class SyncVar[A] {
     wait(timeout)
     val elapsed = System.nanoTime() - start
     // nanoTime should be monotonic, but it's not possible to rely on that.
-    // See http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6458294.
+    // See http://bugs.java.com/bugdatabase/view_bug.do?bug_id=6458294.
     if (elapsed < 0) 0 else TimeUnit.NANOSECONDS.toMillis(elapsed)
   }
 
diff --git a/src/library/scala/concurrent/impl/Promise.scala b/src/library/scala/concurrent/impl/Promise.scala
index 078ad45be9..3538ac6b94 100644
--- a/src/library/scala/concurrent/impl/Promise.scala
+++ b/src/library/scala/concurrent/impl/Promise.scala
@@ -178,7 +178,9 @@ private[concurrent] object Promise {
    * DefaultPromises, and `linkedRootOf` is currently only designed to be called
    * by Future.flatMap.
    */
-  final class DefaultPromise[T] extends AtomicReference[AnyRef](Nil) with Promise[T] {
+  // Left non-final to enable addition of extra fields by Java/Scala converters
+  // in scala-java8-compat.
+  class DefaultPromise[T] extends AtomicReference[AnyRef](Nil) with Promise[T] {
 
     /** Get the root promise for this promise, compressing the link chain to that
      *  promise if necessary.
@@ -248,12 +250,12 @@ private[concurrent] object Promise {
 
     @throws(classOf[TimeoutException])
     @throws(classOf[InterruptedException])
-    def ready(atMost: Duration)(implicit permit: CanAwait): this.type =
+    final def ready(atMost: Duration)(implicit permit: CanAwait): this.type =
       if (tryAwait(atMost)) this
       else throw new TimeoutException("Futures timed out after [" + atMost + "]")
 
     @throws(classOf[Exception])
-    def result(atMost: Duration)(implicit permit: CanAwait): T =
+    final def result(atMost: Duration)(implicit permit: CanAwait): T =
       ready(atMost).value.get.get // ready throws TimeoutException if timeout so value.get is safe here
 
     def value: Option[Try[T]] = value0
@@ -265,7 +267,7 @@ private[concurrent] object Promise {
       case _ => None
     }
 
-    override def isCompleted: Boolean = isCompleted0
+    override final def isCompleted: Boolean = isCompleted0
 
     @tailrec
     private def isCompleted0: Boolean = get() match {
@@ -274,7 +276,7 @@ private[concurrent] object Promise {
       case _ => false
     }
 
-    def tryComplete(value: Try[T]): Boolean = {
+    final def tryComplete(value: Try[T]): Boolean = {
       val resolved = resolveTry(value)
       tryCompleteAndGetListeners(resolved) match {
         case null             => false
@@ -297,7 +299,7 @@ private[concurrent] object Promise {
       }
     }
 
-    def onComplete[U](func: Try[T] => U)(implicit executor: ExecutionContext): Unit =
+    final def onComplete[U](func: Try[T] => U)(implicit executor: ExecutionContext): Unit =
       dispatchOrAddCallback(new CallbackRunnable[T](executor.prepare(), func))
 
     /** Tries to add the callback, if already completed, it dispatches the callback to be executed.
diff --git a/src/library/scala/concurrent/util/Unsafe.java b/src/library/scala/concurrent/util/Unsafe.java
deleted file mode 100644
index 73739e377d..0000000000
--- a/src/library/scala/concurrent/util/Unsafe.java
+++ /dev/null
@@ -1,38 +0,0 @@
-/*                     __                                               *\
-**     ________ ___   / /  ___     Scala API                            **
-**    / __/ __// _ | / /  / _ |    (c) 2003-2013, LAMP/EPFL             **
-**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
-** /____/\___/_/ |_/____/_/ | |                                         **
-**                          |/                                          **
-\*                                                                      */
-
-package scala.concurrent.util;
-import java.lang.reflect.Field;
-
-// TODO: remove once akka no longer needs it, hopefully by 2.12.0-M3!
-@Deprecated
-public final class Unsafe {
-  @Deprecated
-  public final static sun.misc.Unsafe instance;
-  static {
-    try {
-      sun.misc.Unsafe found = null;
-      for(Field field : sun.misc.Unsafe.class.getDeclaredFields()) {
-        if (field.getType() == sun.misc.Unsafe.class) {
-          field.setAccessible(true);
-          found = (sun.misc.Unsafe) field.get(null);
-          break;
-        }
-      }
-      if (found == null) throw new IllegalStateException("Can't find instance of sun.misc.Unsafe");
-      else instance = found;
-    } catch(Throwable t) {
-      throw new ExceptionInInitializerError(t);
-    }
-  }
-}
-
-// Scala version:
-// classOf[sun.misc.Unsafe].getDeclaredFields.filter(_.getType == classOf[sun.misc.Unsafe]).headOption.map { field =>
-//   field.setAccessible(true); field.get(null).asInstanceOf[sun.misc.Unsafe]
-// } getOrElse (throw new IllegalStateException("Can't find instance of sun.misc.Unsafe"))
diff --git a/src/library/scala/io/Codec.scala b/src/library/scala/io/Codec.scala
index 60f99199cb..2a41e25b01 100644
--- a/src/library/scala/io/Codec.scala
+++ b/src/library/scala/io/Codec.scala
@@ -22,7 +22,7 @@ import scala.language.implicitConversions
 //   <?xml version="1.0" encoding="ISO8859-1" ?>
 //
 // MacRoman vs. UTF-8: see http://jira.codehaus.org/browse/JRUBY-3576
-// -Dfile.encoding: see http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4375816
+// -Dfile.encoding: see http://bugs.java.com/bugdatabase/view_bug.do?bug_id=4375816
 
 /** A class for character encoding/decoding preferences.
  *
diff --git a/src/library/scala/reflect/ClassManifestDeprecatedApis.scala b/src/library/scala/reflect/ClassManifestDeprecatedApis.scala
index ca7a3cddb8..82ec872806 100644
--- a/src/library/scala/reflect/ClassManifestDeprecatedApis.scala
+++ b/src/library/scala/reflect/ClassManifestDeprecatedApis.scala
@@ -218,7 +218,7 @@ object ClassManifestFactory {
   /** ClassManifest for the abstract type `prefix # name`. `upperBound` is not
     * strictly necessary as it could be obtained by reflection. It was
     * added so that erasure can be calculated without reflection.
-    * todo: remove after next boostrap
+    * todo: remove after next bootstrap
     */
   def abstractType[T](prefix: OptManifest[_], name: String, upperbound: ClassManifest[_], args: OptManifest[_]*): ClassManifest[T] =
     new ClassManifest[T] {
@@ -239,4 +239,4 @@ private class ClassTypeManifest[T](
     (if (prefix.isEmpty) "" else prefix.get.toString+"#") +
     (if (runtimeClass.isArray) "Array" else runtimeClass.getName) +
     argString
-}
\ No newline at end of file
+}
diff --git a/src/library/scala/runtime/ScalaRunTime.scala b/src/library/scala/runtime/ScalaRunTime.scala
index a0d89fc0e1..026d5edd29 100644
--- a/src/library/scala/runtime/ScalaRunTime.scala
+++ b/src/library/scala/runtime/ScalaRunTime.scala
@@ -9,11 +9,10 @@
 package scala
 package runtime
 
-import scala.collection.{ Seq, IndexedSeq, TraversableView, AbstractIterator }
+import scala.collection.{ Seq, IndexedSeq, TraversableView, AbstractIterator, GenIterable }
 import scala.collection.mutable.WrappedArray
 import scala.collection.immutable.{ StringLike, NumericRange, List, Stream, Nil, :: }
 import scala.collection.generic.{ Sorted, IsTraversableLike }
-import scala.collection.parallel.ParIterable
 import scala.reflect.{ ClassTag, classTag }
 import scala.util.control.ControlThrowable
 import java.lang.{ Class => jClass }
@@ -156,7 +155,7 @@ object ScalaRunTime {
     arr
   }
 
-  // Java bug: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4071957
+  // Java bug: http://bugs.java.com/bugdatabase/view_bug.do?bug_id=4071957
   // More background at ticket #2318.
   def ensureAccessible(m: JMethod): JMethod = scala.reflect.ensureAccessible(m)
 
@@ -326,8 +325,7 @@ object ScalaRunTime {
       case x if useOwnToString(x)       => x.toString
       case x: AnyRef if isArray(x)      => arrayToString(x)
       case x: scala.collection.Map[_, _]      => x.iterator take maxElements map mapInner mkString (x.stringPrefix + "(", ", ", ")")
-      case x: Iterable[_]               => x.iterator take maxElements map inner mkString (x.stringPrefix + "(", ", ", ")")
-      case x: ParIterable[_]            => x.iterator take maxElements map inner mkString (x.stringPrefix + "(", ", ", ")")
+      case x: GenIterable[_]            => x.iterator take maxElements map inner mkString (x.stringPrefix + "(", ", ", ")")
       case x: Traversable[_]            => x take maxElements map inner mkString (x.stringPrefix + "(", ", ", ")")
       case x: Product1[_] if isTuple(x) => "(" + inner(x._1) + ",)" // that special trailing comma
       case x: Product if isTuple(x)     => x.productIterator map inner mkString ("(", ",", ")")
diff --git a/src/library/scala/runtime/Tuple2Zipped.scala b/src/library/scala/runtime/Tuple2Zipped.scala
index 512c4fbc27..1c432b0403 100644
--- a/src/library/scala/runtime/Tuple2Zipped.scala
+++ b/src/library/scala/runtime/Tuple2Zipped.scala
@@ -110,6 +110,8 @@ final class Tuple2Zipped[El1, Repr1, El2, Repr2](val colls: (TraversableLike[El1
         return
     }
   }
+
+  override def toString = "(%s, %s).zipped".format(colls._1.toString, colls._2.toString)
 }
 
 object Tuple2Zipped {
diff --git a/src/library/scala/runtime/Tuple3Zipped.scala b/src/library/scala/runtime/Tuple3Zipped.scala
index ffd44acf81..3bab86921b 100644
--- a/src/library/scala/runtime/Tuple3Zipped.scala
+++ b/src/library/scala/runtime/Tuple3Zipped.scala
@@ -118,6 +118,8 @@ final class Tuple3Zipped[El1, Repr1, El2, Repr2, El3, Repr3](val colls: (Travers
         return
     }
   }
+
+  override def toString: String = "(%s, %s, %s).zipped".format(colls._1.toString, colls._2.toString, colls._3.toString)
 }
 
 object Tuple3Zipped {
diff --git a/src/library/scala/sys/process/package.scala b/src/library/scala/sys/process/package.scala
index 5ec2e73cb9..0e9a1bfc56 100644
--- a/src/library/scala/sys/process/package.scala
+++ b/src/library/scala/sys/process/package.scala
@@ -157,7 +157,8 @@ package scala.sys {
     *     while(input.read() != -1) count += 1
     *     input.close()
     *   }
-    *   cat ! new ProcessIO(_.close(), byteCounter, _.close())
+    *   val p = cat run new ProcessIO(_.close(), byteCounter, _.close())
+    *   p.exitValue()
     *   count
     * }
     *
diff --git a/src/library/scala/util/Sorting.scala b/src/library/scala/util/Sorting.scala
index ee2bdbc4a7..b4f965f69b 100644
--- a/src/library/scala/util/Sorting.scala
+++ b/src/library/scala/util/Sorting.scala
@@ -88,7 +88,7 @@ object Sorting {
               a(pL - 1) = current
               pL -= 1
             case x if x < 0 =>
-              // Already in place.  Just update indicies.
+              // Already in place.  Just update indices.
               iA += 1
             case _ if iB > pR =>
               // Wrong side.  There's room on the other side, so swap
diff --git a/src/library/scala/util/control/Exception.scala b/src/library/scala/util/control/Exception.scala
index aa30887ba0..24c297a2fc 100644
--- a/src/library/scala/util/control/Exception.scala
+++ b/src/library/scala/util/control/Exception.scala
@@ -105,7 +105,7 @@ object Exception {
         case x if rethrow(x)        => throw x
         case x if pf isDefinedAt x  => pf(x)
       }
-      finally fin map (_.invoke())
+      finally fin foreach (_.invoke())
 
     /* Create an empty Try container with this Catch and the supplied `Finally`. */
     def andFinally(body: => Unit): Catch[T] = fin match {
diff --git a/src/reflect/scala/reflect/api/Types.scala b/src/reflect/scala/reflect/api/Types.scala
index cd7648a44a..f9b49f1730 100644
--- a/src/reflect/scala/reflect/api/Types.scala
+++ b/src/reflect/scala/reflect/api/Types.scala
@@ -588,7 +588,7 @@ trait Types {
   /** An extractor class to create and pattern match with syntax `TypeRef(pre, sym, args)`
    *  Here, `pre` is the prefix of the type reference, `sym` is the symbol
    *  referred to by the type reference, and `args` is a possible empty list of
-   *  type argumenrts.
+   *  type arguments.
    *  @group Extractors
    */
   abstract class TypeRefExtractor {
diff --git a/src/reflect/scala/reflect/internal/ClassfileConstants.scala b/src/reflect/scala/reflect/internal/ClassfileConstants.scala
index e5d97e8959..a4223c1cb5 100644
--- a/src/reflect/scala/reflect/internal/ClassfileConstants.scala
+++ b/src/reflect/scala/reflect/internal/ClassfileConstants.scala
@@ -14,7 +14,7 @@ object ClassfileConstants {
   final val JAVA_MAJOR_VERSION = 45
   final val JAVA_MINOR_VERSION = 3
 
-  /** (see http://java.sun.com/docs/books/jvms/second_edition/jvms-clarify.html)
+  /** (see http://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.1)
    *
    *  If the `ACC_INTERFACE` flag is set, the `ACC_ABSTRACT` flag must also
    *  be set (ch. 2.13.1).
diff --git a/src/reflect/scala/reflect/internal/Definitions.scala b/src/reflect/scala/reflect/internal/Definitions.scala
index 14487a941b..5ce5c39145 100644
--- a/src/reflect/scala/reflect/internal/Definitions.scala
+++ b/src/reflect/scala/reflect/internal/Definitions.scala
@@ -233,6 +233,8 @@ trait Definitions extends api.StandardDefinitions {
       || tp =:= AnyRefTpe
     )
 
+    def isUnitType(tp: Type) = tp.typeSymbol == UnitClass && tp.annotations.isEmpty
+
     def hasMultipleNonImplicitParamLists(member: Symbol): Boolean = hasMultipleNonImplicitParamLists(member.info)
     def hasMultipleNonImplicitParamLists(info: Type): Boolean = info match {
       case PolyType(_, restpe)                                   => hasMultipleNonImplicitParamLists(restpe)
@@ -1105,6 +1107,7 @@ trait Definitions extends api.StandardDefinitions {
     lazy val BridgeClass                = requiredClass[scala.annotation.bridge]
     lazy val ElidableMethodClass        = requiredClass[scala.annotation.elidable]
     lazy val ImplicitNotFoundClass      = requiredClass[scala.annotation.implicitNotFound]
+    lazy val ImplicitAmbiguousClass     = getClassIfDefined("scala.annotation.implicitAmbiguous")
     lazy val MigrationAnnotationClass   = requiredClass[scala.annotation.migration]
     lazy val ScalaStrictFPAttr          = requiredClass[scala.annotation.strictfp]
     lazy val SwitchClass                = requiredClass[scala.annotation.switch]
diff --git a/src/reflect/scala/reflect/internal/Kinds.scala b/src/reflect/scala/reflect/internal/Kinds.scala
index 8ae201f045..902ba9fa80 100644
--- a/src/reflect/scala/reflect/internal/Kinds.scala
+++ b/src/reflect/scala/reflect/internal/Kinds.scala
@@ -237,7 +237,7 @@ trait Kinds {
    *
    * Proper types are represented using ProperTypeKind.
    *
-   * Type constructors are reprented using TypeConKind.
+   * Type constructors are represented using TypeConKind.
    */
   abstract class Kind {
     import Kind.StringState
diff --git a/src/reflect/scala/reflect/internal/Symbols.scala b/src/reflect/scala/reflect/internal/Symbols.scala
index 8a52f0b9d8..05fdfb51ed 100644
--- a/src/reflect/scala/reflect/internal/Symbols.scala
+++ b/src/reflect/scala/reflect/internal/Symbols.scala
@@ -884,10 +884,11 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     // string.  So this needs attention.  For now the fact that migration is
     // private[scala] ought to provide enough protection.
     def hasMigrationAnnotation = hasAnnotation(MigrationAnnotationClass)
-    def migrationMessage    = getAnnotation(MigrationAnnotationClass) flatMap { _.stringArg(0) }
-    def migrationVersion    = getAnnotation(MigrationAnnotationClass) flatMap { _.stringArg(1) }
-    def elisionLevel        = getAnnotation(ElidableMethodClass) flatMap { _.intArg(0) }
-    def implicitNotFoundMsg = getAnnotation(ImplicitNotFoundClass) flatMap { _.stringArg(0) }
+    def migrationMessage     = getAnnotation(MigrationAnnotationClass) flatMap { _.stringArg(0) }
+    def migrationVersion     = getAnnotation(MigrationAnnotationClass) flatMap { _.stringArg(1) }
+    def elisionLevel         = getAnnotation(ElidableMethodClass) flatMap { _.intArg(0) }
+    def implicitNotFoundMsg  = getAnnotation(ImplicitNotFoundClass) flatMap { _.stringArg(0) }
+    def implicitAmbiguousMsg = getAnnotation(ImplicitAmbiguousClass) flatMap { _.stringArg(0) }
 
     def isCompileTimeOnly       = hasAnnotation(CompileTimeOnlyAttr)
     def compileTimeOnlyMessage  = getAnnotation(CompileTimeOnlyAttr) flatMap (_ stringArg 0)
@@ -2123,7 +2124,7 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     /** The package class containing this symbol, or NoSymbol if there
      *  is not one.
      *  TODO: formulate as enclosingSuchThat, after making sure
-     *        we can start with current symbol rather than onwner.
+     *        we can start with current symbol rather than owner.
      *  TODO: Also harmonize with enclClass, enclMethod etc.
      */
     def enclosingPackageClass: Symbol = {
diff --git a/src/reflect/scala/reflect/internal/Trees.scala b/src/reflect/scala/reflect/internal/Trees.scala
index e3f95f9fd8..bbd9df05d2 100644
--- a/src/reflect/scala/reflect/internal/Trees.scala
+++ b/src/reflect/scala/reflect/internal/Trees.scala
@@ -1418,7 +1418,7 @@ trait Trees extends api.Trees {
                            transformTypeDefs(tparams), transform(rhs))
         }
       case LabelDef(name, params, rhs) =>
-        treeCopy.LabelDef(tree, name, transformIdents(params), transform(rhs)) //bq: Martin, once, atOwner(...) works, also change `LamdaLifter.proxy'
+        treeCopy.LabelDef(tree, name, transformIdents(params), transform(rhs)) //bq: Martin, once, atOwner(...) works, also change `LambdaLifter.proxy'
       case PackageDef(pid, stats) =>
         treeCopy.PackageDef(
           tree, transform(pid).asInstanceOf[RefTree],
@@ -1601,7 +1601,7 @@ trait Trees extends api.Trees {
           case _          =>
             // no special handling is required for Function or Import nodes here.
             // as they don't have interesting infos attached to their symbols.
-            // Subsitution of the referenced symbol of Return nodes is handled
+            // Substitution of the referenced symbol of Return nodes is handled
             // in .ChangeOwnerTraverser
         }
         tree match {
diff --git a/src/reflect/scala/reflect/internal/transform/UnCurry.scala b/src/reflect/scala/reflect/internal/transform/UnCurry.scala
index abea8bed9f..85e3ac60e8 100644
--- a/src/reflect/scala/reflect/internal/transform/UnCurry.scala
+++ b/src/reflect/scala/reflect/internal/transform/UnCurry.scala
@@ -40,19 +40,27 @@ trait UnCurry {
           apply(MethodType(h.cloneSymbol.resetFlag(IMPLICIT) :: t, restpe))
         case NullaryMethodType(restpe) =>
           apply(MethodType(List(), restpe))
-        case TypeRef(pre, ByNameParamClass, arg :: Nil) =>
-          apply(functionType(List(), arg))
-        case TypeRef(pre, RepeatedParamClass, arg :: Nil) =>
-          apply(seqType(arg))
-        case TypeRef(pre, JavaRepeatedParamClass, arg :: Nil) =>
-          apply(arrayType(
-            if (isUnboundedGeneric(arg)) ObjectTpe else arg))
+        case DesugaredParameterType(desugaredTpe) =>
+          apply(desugaredTpe)
         case _ =>
           expandAlias(mapOver(tp))
       }
     }
   }
 
+  object DesugaredParameterType {
+    def unapply(tpe: Type): Option[Type] = tpe match {
+      case TypeRef(pre, ByNameParamClass, arg :: Nil) =>
+        Some(functionType(List(), arg))
+      case TypeRef(pre, RepeatedParamClass, arg :: Nil) =>
+        Some(seqType(arg))
+      case TypeRef(pre, JavaRepeatedParamClass, arg :: Nil) =>
+        Some(arrayType(if (isUnboundedGeneric(arg)) ObjectTpe else arg))
+      case _ =>
+        None
+      }
+  }
+
   private val uncurryType = new TypeMap {
     def apply(tp0: Type): Type = {
       val tp = expandAlias(tp0)
diff --git a/src/reflect/scala/reflect/runtime/JavaUniverseForce.scala b/src/reflect/scala/reflect/runtime/JavaUniverseForce.scala
index ea213cadd9..278d081249 100644
--- a/src/reflect/scala/reflect/runtime/JavaUniverseForce.scala
+++ b/src/reflect/scala/reflect/runtime/JavaUniverseForce.scala
@@ -370,6 +370,7 @@ trait JavaUniverseForce { self: runtime.JavaUniverse  =>
     definitions.BridgeClass
     definitions.ElidableMethodClass
     definitions.ImplicitNotFoundClass
+    definitions.ImplicitAmbiguousClass
     definitions.MigrationAnnotationClass
     definitions.ScalaStrictFPAttr
     definitions.SwitchClass
@@ -444,7 +445,7 @@ trait JavaUniverseForce { self: runtime.JavaUniverse  =>
     definitions.ScalaValueClassesNoUnit
     definitions.ScalaValueClasses
 
-
+    uncurry.DesugaredParameterType
     erasure.GenericArray
     erasure.scalaErasure
     erasure.specialScalaErasure
diff --git a/src/repl/scala/tools/nsc/interpreter/IMain.scala b/src/repl/scala/tools/nsc/interpreter/IMain.scala
index 841b4abfa5..3b54f5274e 100644
--- a/src/repl/scala/tools/nsc/interpreter/IMain.scala
+++ b/src/repl/scala/tools/nsc/interpreter/IMain.scala
@@ -133,7 +133,6 @@ class IMain(@BeanProperty val factory: ScriptEngineFactory, initialSettings: Set
     }
     catch AbstractOrMissingHandler()
   }
-  private def tquoted(s: String) = "\"\"\"" + s + "\"\"\""
   private val logScope = scala.sys.props contains "scala.repl.scope"
   private def scopelog(msg: String) = if (logScope) Console.err.println(msg)
 
@@ -888,7 +887,7 @@ class IMain(@BeanProperty val factory: ScriptEngineFactory, initialSettings: Set
     /** Code to import bound names from previous lines - accessPath is code to
       * append to objectName to access anything bound by request.
       */
-    lazy val ComputedImports(importsPreamble, importsTrailer, accessPath) =
+    lazy val ComputedImports(headerPreamble, importsPreamble, importsTrailer, accessPath) =
       exitingTyper(importsCode(referencedNames.toSet, ObjectSourceCode, definesClass))
 
     /** the line of code to compute */
@@ -905,9 +904,13 @@ class IMain(@BeanProperty val factory: ScriptEngineFactory, initialSettings: Set
       def path = originalPath("$intp")
       def envLines = {
         if (!isReplPower) Nil // power mode only for now
-        else List("def %s = %s".format("$line", tquoted(originalLine)), "def %s = Nil".format("$trees"))
+        else {
+          val escapedLine = Constant(originalLine).escapedStringValue
+          List(s"""def $$line = $escapedLine """, """def $trees = _root_.scala.Nil""")
+        }
       }
       def preamble = s"""
+        |$headerPreamble
         |${preambleHeader format lineRep.readName}
         |${envLines mkString ("  ", ";\n  ", ";\n")}
         |$importsPreamble
diff --git a/src/repl/scala/tools/nsc/interpreter/Imports.scala b/src/repl/scala/tools/nsc/interpreter/Imports.scala
index 3ec77e46f1..5b231d94b6 100644
--- a/src/repl/scala/tools/nsc/interpreter/Imports.scala
+++ b/src/repl/scala/tools/nsc/interpreter/Imports.scala
@@ -70,7 +70,10 @@ trait Imports {
 
   /** Compute imports that allow definitions from previous
    *  requests to be visible in a new request.  Returns
-   *  three pieces of related code:
+   *  three or four pieces of related code:
+   *
+   *  0. Header code fragment that should go at the beginning
+   *  of the compilation unit, specifically, import Predef.
    *
    *  1. An initial code fragment that should go before
    *  the code of the new request.
@@ -91,30 +94,34 @@ trait Imports {
    * (3) It imports multiple same-named implicits, but only the
    * last one imported is actually usable.
    */
-  case class ComputedImports(prepend: String, append: String, access: String)
+  case class ComputedImports(header: String, prepend: String, append: String, access: String)
   protected def importsCode(wanted: Set[Name], wrapper: Request#Wrapper, definesClass: Boolean): ComputedImports = {
+    val header, code, trailingBraces, accessPath = new StringBuilder
+    val currentImps = mutable.HashSet[Name]()
+    var predefEscapes = false      // only emit predef import header if name not resolved in history, loosely
+
     /** Narrow down the list of requests from which imports
      *  should be taken.  Removes requests which cannot contribute
      *  useful imports for the specified set of wanted names.
      */
-    case class ReqAndHandler(req: Request, handler: MemberHandler) { }
+    case class ReqAndHandler(req: Request, handler: MemberHandler)
 
     def reqsToUse: List[ReqAndHandler] = {
       /** Loop through a list of MemberHandlers and select which ones to keep.
-        * 'wanted' is the set of names that need to be imported.
+       *  'wanted' is the set of names that need to be imported.
        */
       def select(reqs: List[ReqAndHandler], wanted: Set[Name]): List[ReqAndHandler] = {
         // Single symbol imports might be implicits! See bug #1752.  Rather than
         // try to finesse this, we will mimic all imports for now.
         def keepHandler(handler: MemberHandler) = handler match {
-        /* While defining classes in class based mode - implicits are not needed. */
+          // While defining classes in class based mode - implicits are not needed.
           case h: ImportHandler if isClassBased && definesClass => h.importedNames.exists(x => wanted.contains(x))
           case _: ImportHandler => true
           case x                => x.definesImplicit || (x.definedNames exists wanted)
         }
 
         reqs match {
-          case Nil                                    => Nil
+          case Nil                                    => predefEscapes = wanted contains PredefModule.name ; Nil
           case rh :: rest if !keepHandler(rh.handler) => select(rest, wanted)
           case rh :: rest                             =>
             import rh.handler._
@@ -127,9 +134,6 @@ trait Imports {
       select(allReqAndHandlers reverseMap { case (r, h) => ReqAndHandler(r, h) }, wanted).reverse
     }
 
-    val code, trailingBraces, accessPath = new StringBuilder
-    val currentImps = mutable.HashSet[Name]()
-
     // add code for a new object to hold some imports
     def addWrapper() {
       import nme.{ INTERPRETER_IMPORT_WRAPPER => iw }
@@ -146,6 +150,9 @@ trait Imports {
       try op finally addWrapper()
     }
 
+    // imports from Predef are relocated to the template header to allow hiding.
+    def checkHeader(h: ImportHandler) = h.referencedNames contains PredefModule.name
+
     // loop through previous requests, adding imports for each one
     wrapBeforeAndAfter {
       // Reusing a single temporary value when import from a line with multiple definitions.
@@ -153,6 +160,9 @@ trait Imports {
       for (ReqAndHandler(req, handler) <- reqsToUse) {
         val objName = req.lineRep.readPathInstance
         handler match {
+          case h: ImportHandler if checkHeader(h) =>
+            header.clear()
+            header append f"${h.member}%n"
           // If the user entered an import, then just use it; add an import wrapping
           // level if the import might conflict with some other import
           case x: ImportHandler if x.importsWildcard =>
@@ -194,7 +204,8 @@ trait Imports {
       }
     }
 
-    ComputedImports(code.toString, trailingBraces.toString, accessPath.toString)
+    val computedHeader = if (predefEscapes) header.toString else ""
+    ComputedImports(computedHeader, code.toString, trailingBraces.toString, accessPath.toString)
   }
 
   private def allReqAndHandlers =
diff --git a/src/scaladoc/scala/tools/nsc/doc/html/page/Template.scala b/src/scaladoc/scala/tools/nsc/doc/html/page/Template.scala
index 743c2a401c..0353e58e67 100644
--- a/src/scaladoc/scala/tools/nsc/doc/html/page/Template.scala
+++ b/src/scaladoc/scala/tools/nsc/doc/html/page/Template.scala
@@ -787,7 +787,7 @@ class Template(universe: doc.Universe, generator: DiagramGenerator, tpl: DocTemp
           if (isReduced) NodeSeq.Empty else {
             def paramsToHtml(vlsss: List[List[ValueParam]]): NodeSeq = {
               def param0(vl: ValueParam): NodeSeq =
-                // notice the }{ in the next lines, they are necessary to avoid an undesired withspace in output
+                // notice the }{ in the next lines, they are necessary to avoid an undesired whitespace in output
                 <span name={ vl.name }>{
                   Text(vl.name)
                 }{ Text(": ") ++ typeToHtml(vl.resultType, hasLinks) }{
diff --git a/src/scaladoc/scala/tools/nsc/doc/html/page/diagram/DotRunner.scala b/src/scaladoc/scala/tools/nsc/doc/html/page/diagram/DotRunner.scala
index 4bed106f43..9381cf3a35 100644
--- a/src/scaladoc/scala/tools/nsc/doc/html/page/diagram/DotRunner.scala
+++ b/src/scaladoc/scala/tools/nsc/doc/html/page/diagram/DotRunner.scala
@@ -145,7 +145,7 @@ class DotProcess(settings: doc.Settings) {
         // we shouldn't just sit there for 50s not reporting anything, no?
         settings.printMsg("Graphviz dot encountered an error when generating the diagram for:")
         settings.printMsg(templateName)
-        settings.printMsg("These are usually spurious errors, but if you notice a persistant error on")
+        settings.printMsg("These are usually spurious errors, but if you notice a persistent error on")
         settings.printMsg("a diagram, please use the " + settings.docDiagramsDebug.name + " flag and report a bug with the output.")
       }
     }