Merge remote-tracking branch 'origin/2.10.x' into merge-210

* origin/2.10.x: (68 commits)
  Eliminate breaking relative names in source.
  "Hot fix" for broken build.
  Fix SI-4813 - Clone doesn't work on LinkedList.
  Made 'def clone()' consistent with parens everywhere.
  accommodates pull request feedback
  SI-6310 redeploys the starr
  SI-6310 AbsTypeTag => WeakTypeTag
  SI-6323 outlaws free types from TypeTag
  SI-6323 prohibits reflection against free types
  improvements for reification of free symbols
  removes build.newFreeExistential
  SI-6359 Deep prohibition of templates in value class
  Fixes SI-6259.  Unable to use typeOf in super call of top-level object.
  Fixes binary repo push for new typesafe repo layouts.
  Better error message for pattern arity errors.
  Rescued TreeBuilder from the parser.
  Pending test for SI-3943
  Test case for a bug fixed in M7.
  Fix for SI-6367, exponential time in inference.
  SI-6306 Remove incorrect eta-expansion optimization in Uncurry
  ...

Conflicts:
	src/compiler/scala/tools/nsc/transform/AddInterfaces.scala
	src/compiler/scala/tools/nsc/transform/SpecializeTypes.scala

16 files changed, 172 insertions, 94 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Analyzer.scala b/src/compiler/scala/tools/nsc/typechecker/Analyzer.scala
index 8218289f93..3526d932d3 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Analyzer.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Analyzer.scala
@@ -6,7 +6,7 @@
 package scala.tools.nsc
 package typechecker
 
-import reflect.internal.util.Statistics
+import scala.reflect.internal.util.Statistics
 
 /** The main attribution phase.
  */
@@ -72,7 +72,7 @@ trait Analyzer extends AnyRef
   }
 
   object typerFactory extends SubComponent {
-    import reflect.internal.TypesStats.typerNanos
+    import scala.reflect.internal.TypesStats.typerNanos
     val global: Analyzer.this.global.type = Analyzer.this.global
     val phaseName = "typer"
     val runsAfter = List[String]()
diff --git a/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala b/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala
index 6b69184d0a..f9f61b10a4 100644
--- a/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala
@@ -467,9 +467,6 @@ trait ContextErrors {
       def NamedAndDefaultArgumentsNotSupportedForMacros(tree: Tree, fun: Tree) =
         NormalTypeError(tree, "macros application do not support named and/or default arguments")
 
-      def WrongNumberOfArgsError(tree: Tree, fun: Tree) =
-        NormalTypeError(tree, "wrong number of arguments for "+ treeSymTypeMsg(fun))
-
       def TooManyArgsNamesDefaultsError(tree: Tree, fun: Tree) =
         NormalTypeError(tree, "too many arguments for "+treeSymTypeMsg(fun))
 
@@ -509,8 +506,8 @@ trait ContextErrors {
       def TooManyArgsPatternError(fun: Tree) =
         NormalTypeError(fun, "too many arguments for unapply pattern, maximum = "+definitions.MaxTupleArity)
 
-      def WrongNumberArgsPatternError(tree: Tree, fun: Tree) =
-        NormalTypeError(tree, "wrong number of arguments for "+treeSymTypeMsg(fun))
+      def WrongNumberOfArgsError(tree: Tree, fun: Tree) =
+        NormalTypeError(tree, "wrong number of arguments for "+ treeSymTypeMsg(fun))
 
       def ApplyWithoutArgsError(tree: Tree, fun: Tree) =
         NormalTypeError(tree, fun.tpe+" does not take parameters")
@@ -738,7 +735,7 @@ trait ContextErrors {
         )
         val forgotten = (
           if (sym.isTerm) "splice when splicing this variable into a reifee"
-          else "c.AbsTypeTag annotation for this type parameter"
+          else "c.WeakTypeTag annotation for this type parameter"
         )
         macroExpansionError(expandee, template(sym.name.nameKind).format(sym.name + " " + sym.origin, forgotten))
       }
@@ -1234,7 +1231,7 @@ trait ContextErrors {
       message + suffix
     }
 
-    private def abbreviateCoreAliases(s: String): String = List("AbsTypeTag", "Expr").foldLeft(s)((res, x) => res.replace("c.universe." + x, "c." + x))
+    private def abbreviateCoreAliases(s: String): String = List("WeakTypeTag", "Expr").foldLeft(s)((res, x) => res.replace("c.universe." + x, "c." + x))
 
     private def showMeth(pss: List[List[Symbol]], restpe: Type, abbreviate: Boolean) = {
       var argsPart = (pss map (ps => ps map (_.defString) mkString ("(", ", ", ")"))).mkString
@@ -1313,7 +1310,7 @@ trait ContextErrors {
     // aXXX (e.g. aparams) => characteristics of the macro impl ("a" stands for "actual")
     // rXXX (e.g. rparams) => characteristics of a reference macro impl signature synthesized from the macro def ("r" stands for "reference")
 
-    def MacroImplNonTagImplicitParameters(params: List[Symbol]) = compatibilityError("macro implementations cannot have implicit parameters other than AbsTypeTag evidences")
+    def MacroImplNonTagImplicitParameters(params: List[Symbol]) = compatibilityError("macro implementations cannot have implicit parameters other than WeakTypeTag evidences")
 
     def MacroImplParamssMismatchError() = compatibilityError("number of parameter sections differ")
 
diff --git a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
index 6a908c6c65..dbf769c79f 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
@@ -8,7 +8,7 @@ package typechecker
 
 import symtab.Flags._
 import scala.collection.mutable.{LinkedHashSet, Set}
-import annotation.tailrec
+import scala.annotation.tailrec
 
 /**
  *  @author  Martin Odersky
diff --git a/src/compiler/scala/tools/nsc/typechecker/DestructureTypes.scala b/src/compiler/scala/tools/nsc/typechecker/DestructureTypes.scala
index 5802d36878..6a21639391 100644
--- a/src/compiler/scala/tools/nsc/typechecker/DestructureTypes.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/DestructureTypes.scala
@@ -6,7 +6,7 @@
 package scala.tools.nsc
 package typechecker
 
-import language.implicitConversions
+import scala.language.implicitConversions
 
 /** A generic means of breaking down types into their subcomponents.
  *  Types are decomposed top down, and recognizable substructure is
diff --git a/src/compiler/scala/tools/nsc/typechecker/Duplicators.scala b/src/compiler/scala/tools/nsc/typechecker/Duplicators.scala
index 745250e167..2dd0836322 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Duplicators.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Duplicators.scala
@@ -29,7 +29,7 @@ abstract class Duplicators extends Analyzer {
    *  the old class with the new class, and map symbols through the given 'env'. The
    *  environment is a map from type skolems to concrete types (see SpecializedTypes).
    */
-  def retyped(context: Context, tree: Tree, oldThis: Symbol, newThis: Symbol, env: collection.Map[Symbol, Type]): Tree = {
+  def retyped(context: Context, tree: Tree, oldThis: Symbol, newThis: Symbol, env: scala.collection.Map[Symbol, Type]): Tree = {
     if (oldThis ne newThis) {
       oldClassOwner = oldThis
       newClassOwner = newThis
diff --git a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
index 6a91922b4c..e3f0756b6c 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Implicits.scala
@@ -11,13 +11,13 @@
 package scala.tools.nsc
 package typechecker
 
-import annotation.tailrec
+import scala.annotation.tailrec
 import scala.collection.{ mutable, immutable }
 import mutable.{ LinkedHashMap, ListBuffer }
 import scala.util.matching.Regex
 import symtab.Flags._
 import scala.reflect.internal.util.Statistics
-import language.implicitConversions
+import scala.language.implicitConversions
 
 /** This trait provides methods to find various kinds of implicits.
  *
@@ -1151,7 +1151,7 @@ trait Implicits {
     private def TagSymbols =  TagMaterializers.keySet
     private val TagMaterializers = Map[Symbol, Symbol](
       ClassTagClass   -> MacroInternal_materializeClassTag,
-      AbsTypeTagClass -> MacroInternal_materializeAbsTypeTag,
+      WeakTypeTagClass -> MacroInternal_materializeWeakTypeTag,
       TypeTagClass    -> MacroInternal_materializeTypeTag
     )
 
@@ -1217,14 +1217,14 @@ trait Implicits {
     private val ManifestSymbols = Set[Symbol](PartialManifestClass, FullManifestClass, OptManifestClass)
 
     /** Creates a tree that calls the relevant factory method in object
-      * reflect.Manifest for type 'tp'. An EmptyTree is returned if
+      * scala.reflect.Manifest for type 'tp'. An EmptyTree is returned if
       * no manifest is found. todo: make this instantiate take type params as well?
       */
     private def manifestOfType(tp: Type, flavor: Symbol): SearchResult = {
       val full = flavor == FullManifestClass
       val opt = flavor == OptManifestClass
 
-      /** Creates a tree that calls the factory method called constructor in object reflect.Manifest */
+      /** Creates a tree that calls the factory method called constructor in object scala.reflect.Manifest */
       def manifestFactoryCall(constructor: String, tparg: Type, args: Tree*): Tree =
         if (args contains EmptyTree) EmptyTree
         else typedPos(tree.pos.focus) {
@@ -1472,7 +1472,7 @@ trait Implicits {
         interpolate(msg, Map((typeParamNames zip typeArgs): _*)) // TODO: give access to the name and type of the implicit argument, etc?
 
       def validate: Option[String] = {
-        import scala.util.matching.Regex; import collection.breakOut
+        import scala.util.matching.Regex; import scala.collection.breakOut
         // is there a shorter way to avoid the intermediate toList?
         val refs = """\$\{([^}]+)\}""".r.findAllIn(msg).matchData.map(_ group 1).toSet
         val decls = typeParamNames.toSet
@@ -1492,7 +1492,7 @@ trait Implicits {
 
 object ImplicitsStats {
 
-  import reflect.internal.TypesStats._
+  import scala.reflect.internal.TypesStats._
 
   val rawTypeImpl         = Statistics.newSubCounter ("  of which in implicits", rawTypeCount)
   val subtypeImpl         = Statistics.newSubCounter("  of which in implicit", subtypeCount)
diff --git a/src/compiler/scala/tools/nsc/typechecker/Infer.scala b/src/compiler/scala/tools/nsc/typechecker/Infer.scala
index 96dcbb5b80..12766116d1 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Infer.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Infer.scala
@@ -941,10 +941,13 @@ trait Infer {
     /** Is sym1 (or its companion class in case it is a module) a subclass of
      *  sym2 (or its companion class in case it is a module)?
      */
-    def isProperSubClassOrObject(sym1: Symbol, sym2: Symbol): Boolean =
-      sym1 != sym2 && sym1 != NoSymbol && (sym1 isSubClass sym2) ||
-      sym1.isModuleClass && isProperSubClassOrObject(sym1.linkedClassOfClass, sym2) ||
-      sym2.isModuleClass && isProperSubClassOrObject(sym1, sym2.linkedClassOfClass)
+    def isProperSubClassOrObject(sym1: Symbol, sym2: Symbol): Boolean = (
+      (sym1 != sym2) && (sym1 != NoSymbol) && (
+           (sym1 isSubClass sym2)
+        || (sym1.isModuleClass && isProperSubClassOrObject(sym1.linkedClassOfClass, sym2))
+        || (sym2.isModuleClass && isProperSubClassOrObject(sym1, sym2.linkedClassOfClass))
+      )
+    )
 
     /** is symbol `sym1` defined in a proper subclass of symbol `sym2`?
      */
diff --git a/src/compiler/scala/tools/nsc/typechecker/Macros.scala b/src/compiler/scala/tools/nsc/typechecker/Macros.scala
index 01e773e528..7e9b288853 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Macros.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Macros.scala
@@ -7,7 +7,7 @@ import scala.tools.nsc.util.ClassPath._
 import scala.reflect.runtime.ReflectionUtils
 import scala.collection.mutable.ListBuffer
 import scala.compat.Platform.EOL
-import reflect.internal.util.Statistics
+import scala.reflect.internal.util.Statistics
 import scala.reflect.macros.util._
 import java.lang.{Class => jClass}
 import java.lang.reflect.{Array => jArray, Method => jMethod}
@@ -26,7 +26,7 @@ import scala.reflect.macros.runtime.AbortMacroException
  *
  *  Then fooBar needs to point to a static method of the following form:
  *
- *    def fooBar[T: c.AbsTypeTag] // type tag annotation is optional
+ *    def fooBar[T: c.WeakTypeTag] // type tag annotation is optional
  *           (c: scala.reflect.macros.Context)
  *           (xs: c.Expr[List[T]])
  *           : c.Expr[T] = {
@@ -84,7 +84,7 @@ trait Macros extends scala.tools.reflect.FastTrack with Traces {
     val methName: String,
     // flattens the macro impl's parameter lists having symbols replaced with metadata
     // currently metadata is an index of the type parameter corresponding to that type tag (if applicable)
-    // f.ex. for: def impl[T: AbsTypeTag, U: AbsTypeTag, V](c: Context)(x: c.Expr[T]): (U, V) = ???
+    // f.ex. for: def impl[T: WeakTypeTag, U: WeakTypeTag, V](c: Context)(x: c.Expr[T]): (U, V) = ???
     // `signature` will be equal to List(-1, -1, 0, 1)
     val signature: List[Int],
     // type arguments part of a macro impl ref (the right-hand side of a macro definition)
@@ -216,7 +216,7 @@ trait Macros extends scala.tools.reflect.FastTrack with Traces {
   }
 
   /** Transforms parameters lists of a macro impl.
-   *  The `transform` function is invoked only for AbsTypeTag evidence parameters.
+   *  The `transform` function is invoked only for WeakTypeTag evidence parameters.
    *
    *  The transformer takes two arguments: a value parameter from the parameter list
    *  and a type parameter that is witnesses by the value parameter.
@@ -232,7 +232,7 @@ trait Macros extends scala.tools.reflect.FastTrack with Traces {
     if (paramss.isEmpty || paramss.last.isEmpty) return paramss // no implicit parameters in the signature => nothing to do
     if (paramss.head.isEmpty || !(paramss.head.head.tpe <:< MacroContextClass.tpe)) return paramss // no context parameter in the signature => nothing to do
     def transformTag(param: Symbol): Symbol = param.tpe.dealias match {
-      case TypeRef(SingleType(SingleType(NoPrefix, c), universe), AbsTypeTagClass, targ :: Nil)
+      case TypeRef(SingleType(SingleType(NoPrefix, c), universe), WeakTypeTagClass, targ :: Nil)
       if c == paramss.head.head && universe == MacroContextUniverse =>
         transform(param, targ.typeSymbol)
       case _ =>
@@ -336,7 +336,7 @@ trait Macros extends scala.tools.reflect.FastTrack with Traces {
             RepeatedParamClass.typeConstructor,
             List(implType(isType, sigma(origTpe.typeArgs.head))))
         else {
-          val tsym = getMember(MacroContextClass, if (isType) tpnme.AbsTypeTag else tpnme.Expr)
+          val tsym = getMember(MacroContextClass, if (isType) tpnme.WeakTypeTag else tpnme.Expr)
           typeRef(singleType(NoPrefix, ctxParam), tsym, List(sigma(origTpe)))
         }
       val paramCache = collection.mutable.Map[Symbol, Symbol]()
@@ -630,7 +630,7 @@ trait Macros extends scala.tools.reflect.FastTrack with Traces {
                 macroDef.owner)
           } else
             targ.tpe
-          if (tpe.isConcrete) context.TypeTag(tpe) else context.AbsTypeTag(tpe)
+          context.WeakTypeTag(tpe)
         })
         macroTraceVerbose("tags: ")(tags)
 
@@ -832,7 +832,7 @@ trait Macros extends scala.tools.reflect.FastTrack with Traces {
   var hasPendingMacroExpansions = false
   private val delayed = perRunCaches.newWeakMap[Tree, collection.mutable.Set[Int]]
   private def isDelayed(expandee: Tree) = delayed contains expandee
-  private def calculateUndetparams(expandee: Tree): collection.mutable.Set[Int] =
+  private def calculateUndetparams(expandee: Tree): scala.collection.mutable.Set[Int] =
     delayed.get(expandee).getOrElse {
       val calculated = collection.mutable.Set[Symbol]()
       expandee foreach (sub => {
@@ -872,13 +872,13 @@ trait Macros extends scala.tools.reflect.FastTrack with Traces {
     new Transformer {
       override def transform(tree: Tree) = super.transform(tree match {
         // todo. expansion should work from the inside out
-        case wannabe if (delayed contains wannabe) && calculateUndetparams(wannabe).isEmpty =>
-          val context = wannabe.attachments.get[MacroRuntimeAttachment].get.typerContext
-          delayed -= wannabe
+        case tree if (delayed contains tree) && calculateUndetparams(tree).isEmpty =>
+          val context = tree.attachments.get[MacroRuntimeAttachment].get.typerContext
+          delayed -= tree
           context.implicitsEnabled = typer.context.implicitsEnabled
           context.enrichmentEnabled = typer.context.enrichmentEnabled
           context.macrosEnabled = typer.context.macrosEnabled
-          macroExpand(newTyper(context), wannabe, EXPRmode, WildcardType)
+          macroExpand(newTyper(context), tree, EXPRmode, WildcardType)
         case _ =>
           tree
       })
@@ -886,7 +886,7 @@ trait Macros extends scala.tools.reflect.FastTrack with Traces {
 }
 
 object MacrosStats {
-  import reflect.internal.TypesStats.typerNanos
+  import scala.reflect.internal.TypesStats.typerNanos
   val macroExpandCount    = Statistics.newCounter ("#macro expansions", "typer")
   val macroExpandNanos    = Statistics.newSubTimer("time spent in macroExpand", typerNanos)
 }
diff --git a/src/compiler/scala/tools/nsc/typechecker/MethodSynthesis.scala b/src/compiler/scala/tools/nsc/typechecker/MethodSynthesis.scala
index 4f597f97c9..91dcd90962 100644
--- a/src/compiler/scala/tools/nsc/typechecker/MethodSynthesis.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/MethodSynthesis.scala
@@ -10,7 +10,7 @@ import scala.collection.{ mutable, immutable }
 import scala.reflect.internal.util.StringOps.{ ojoin }
 import scala.reflect.ClassTag
 import scala.reflect.runtime.{ universe => ru }
-import language.higherKinds
+import scala.language.higherKinds
 
 /** Logic related to method synthesis which involves cooperation between
  *  Namer and Typer.
@@ -369,7 +369,7 @@ trait MethodSynthesis {
     }
 
     /** A synthetic method which performs the implicit conversion implied by
-     *  the declaration of an implicit class.  Yet to be written.
+     *  the declaration of an implicit class.
      */
     case class ImplicitClassWrapper(tree: ClassDef) extends DerivedFromClassDef {
       def completer(sym: Symbol): Type = ??? // not needed
@@ -377,7 +377,7 @@ trait MethodSynthesis {
       def derivedSym: Symbol = {
         // Only methods will do! Don't want to pick up any stray
         // companion objects of the same name.
-        val result = enclClass.info decl name suchThat (_.isMethod)
+        val result = enclClass.info decl name suchThat (x => x.isMethod && x.isSynthetic)
         assert(result != NoSymbol, "not found: "+name+" in "+enclClass+" "+enclClass.info.decls)
         result
       }
diff --git a/src/compiler/scala/tools/nsc/typechecker/Namers.scala b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
index 18b3fe5f4c..7f14216e76 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Namers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Namers.scala
@@ -359,10 +359,39 @@ trait Namers extends MethodSynthesis {
       }
     }
 
+    /** Given a ClassDef or ModuleDef, verifies there isn't a companion which
+     *  has been defined in a separate file.
+     */
+    private def validateCompanionDefs(tree: ImplDef) {
+      val sym = tree.symbol
+      if (sym eq NoSymbol) return
+
+      val ctx    = if (context.owner.isPackageObjectClass) context.outer else context
+      val module = if (sym.isModule) sym else ctx.scope lookup tree.name.toTermName
+      val clazz  = if (sym.isClass) sym else ctx.scope lookup tree.name.toTypeName
+      val fails  = (
+           module.isModule
+        && clazz.isClass
+        && !module.isSynthetic
+        && !clazz.isSynthetic
+        && (clazz.sourceFile ne null)
+        && (module.sourceFile ne null)
+        && !(module isCoDefinedWith clazz)
+      )
+      if (fails) {
+        context.unit.error(tree.pos, (
+            s"Companions '$clazz' and '$module' must be defined in same file:\n"
+          + s"  Found in ${clazz.sourceFile.canonicalPath} and ${module.sourceFile.canonicalPath}")
+        )
+      }
+    }
+
     def enterModuleDef(tree: ModuleDef) = {
       val sym = enterModuleSymbol(tree)
       sym.moduleClass setInfo namerOf(sym).moduleClassTypeCompleter(tree)
       sym setInfo completerOf(tree)
+      validateCompanionDefs(tree)
+      sym
     }
 
     /** Enter a module symbol. The tree parameter can be either
@@ -467,7 +496,6 @@ trait Namers extends MethodSynthesis {
             // for Java code importing Scala objects
             if (!nme.isModuleName(from) || isValid(nme.stripModuleSuffix(from))) {
               typer.TyperErrorGen.NotAMemberError(tree, expr, from)
-              typer.infer.setError(tree)
             }
           }
           // Setting the position at the import means that if there is
@@ -635,6 +663,7 @@ trait Namers extends MethodSynthesis {
         }
         else context.unit.error(tree.pos, "implicit classes must accept exactly one primary constructor parameter")
       }
+      validateCompanionDefs(tree)
     }
 
     // this logic is needed in case typer was interrupted half
@@ -699,7 +728,7 @@ trait Namers extends MethodSynthesis {
       // }
     }
 
-    def moduleClassTypeCompleter(tree: Tree) = {
+    def moduleClassTypeCompleter(tree: ModuleDef) = {
       mkTypeCompleter(tree) { sym =>
         val moduleSymbol = tree.symbol
         assert(moduleSymbol.moduleClass == sym, moduleSymbol.moduleClass)
@@ -1545,18 +1574,11 @@ trait Namers extends MethodSynthesis {
    *  call this method?
    */
   def companionSymbolOf(original: Symbol, ctx: Context): Symbol = {
-    try {
-      original.companionSymbol orElse {
-        ctx.lookup(original.name.companionName, original.owner).suchThat(sym =>
-          (original.isTerm || sym.hasModuleFlag) &&
-          (sym isCoDefinedWith original)
-        )
-      }
-    }
-    catch {
-      case e: InvalidCompanions =>
-        ctx.unit.error(original.pos, e.getMessage)
-        NoSymbol
+    original.companionSymbol orElse {
+      ctx.lookup(original.name.companionName, original.owner).suchThat(sym =>
+        (original.isTerm || sym.hasModuleFlag) &&
+        (sym isCoDefinedWith original)
+      )
     }
   }
 }
diff --git a/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala b/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala
index 14c9aca078..7a035bb33b 100644
--- a/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/PatternMatching.scala
@@ -9,12 +9,12 @@ package typechecker
 
 import symtab._
 import Flags.{MUTABLE, METHOD, LABEL, SYNTHETIC, ARTIFACT}
-import language.postfixOps
+import scala.language.postfixOps
 import scala.tools.nsc.transform.TypingTransformers
 import scala.tools.nsc.transform.Transform
 import scala.collection.mutable.HashSet
 import scala.collection.mutable.HashMap
-import reflect.internal.util.Statistics
+import scala.reflect.internal.util.Statistics
 import scala.reflect.internal.Types
 
 /** Translate pattern matching.
@@ -2941,7 +2941,7 @@ trait PatternMatching extends Transform with TypingTransformers with ast.TreeDSL
       }
 
       // node in the tree that describes how to construct a counter-example
-      case class VariableAssignment(variable: Var, equalTo: List[Const], notEqualTo: List[Const], fields: collection.mutable.Map[Symbol, VariableAssignment]) {
+      case class VariableAssignment(variable: Var, equalTo: List[Const], notEqualTo: List[Const], fields: scala.collection.mutable.Map[Symbol, VariableAssignment]) {
         // need to prune since the model now incorporates all super types of a constant (needed for reachability)
         private lazy val uniqueEqualTo = equalTo filterNot (subsumed => equalTo.exists(better => (better ne subsumed) && instanceOfTpImplies(better.tp, subsumed.tp)))
         private lazy val prunedEqualTo = uniqueEqualTo filterNot (subsumed => variable.staticTpCheckable <:< subsumed.tp)
diff --git a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
index 93a8dfc9cb..2335a9e3b6 100644
--- a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
@@ -7,10 +7,10 @@ package scala.tools.nsc
 package typechecker
 
 import symtab.Flags._
-import collection.{ mutable, immutable }
+import scala.collection.{ mutable, immutable }
 import transform.InfoTransform
 import scala.collection.mutable.ListBuffer
-import language.postfixOps
+import scala.language.postfixOps
 
 /** <p>
  *    Post-attribution checking and transformation.
@@ -38,7 +38,7 @@ import language.postfixOps
  *
  *  @todo    Check whether we always check type parameter bounds.
  */
-abstract class RefChecks extends InfoTransform with reflect.internal.transform.RefChecks {
+abstract class RefChecks extends InfoTransform with scala.reflect.internal.transform.RefChecks {
 
   val global: Global               // need to repeat here because otherwise last mixin defines global as
                                    // SymbolTable. If we had DOT this would not be an issue
@@ -430,6 +430,7 @@ abstract class RefChecks extends InfoTransform with reflect.internal.transform.R
             overrideError("cannot override a macro")
           } else {
             checkOverrideTypes()
+            checkOverrideDeprecated()
             if (settings.warnNullaryOverride.value) {
               if (other.paramss.isEmpty && !member.paramss.isEmpty) {
                 unit.warning(member.pos, "non-nullary method overrides nullary method")
@@ -508,6 +509,14 @@ abstract class RefChecks extends InfoTransform with reflect.internal.transform.R
             }
           }
         }
+
+        def checkOverrideDeprecated() {
+          if (other.hasDeprecatedOverridingAnnotation) {
+            val suffix = other.deprecatedOverridingMessage map (": " + _) getOrElse ""
+            val msg = s"overriding ${other.fullLocationString} is deprecated$suffix"
+            unit.deprecationWarning(member.pos, msg)
+          }
+        }
       }
 
       val opc = new overridingPairs.Cursor(clazz)
@@ -1199,6 +1208,23 @@ abstract class RefChecks extends InfoTransform with reflect.internal.transform.R
       case _ =>
     }
 
+    // SI-6276 warn for `def foo = foo` or `val bar: X = bar`, which come up more frequently than you might think.
+    def checkInfiniteLoop(valOrDef: ValOrDefDef) {
+      def callsSelf = valOrDef.rhs match {
+        case t @ (Ident(_) | Select(This(_), _)) =>
+          t hasSymbolWhich (_.accessedOrSelf == valOrDef.symbol)
+        case _ => false
+      }
+      val trivialInifiniteLoop = (
+        !valOrDef.isErroneous
+     && !valOrDef.symbol.isValueParameter
+     && valOrDef.symbol.paramss.isEmpty
+     && callsSelf
+      )
+      if (trivialInifiniteLoop)
+        unit.warning(valOrDef.rhs.pos, s"${valOrDef.symbol.fullLocationString} does nothing other than call itself recursively")
+    }
+
 // Transformation ------------------------------------------------------------
 
     /* Convert a reference to a case factory of type `tpe` to a new of the class it produces. */
@@ -1642,6 +1668,7 @@ abstract class RefChecks extends InfoTransform with reflect.internal.transform.R
 
           case ValDef(_, _, _, _) | DefDef(_, _, _, _, _, _) =>
             checkDeprecatedOvers(tree)
+            checkInfiniteLoop(tree.asInstanceOf[ValOrDefDef])
             if (settings.warnNullaryUnit.value)
               checkNullaryMethodReturnType(sym)
             if (settings.warnInaccessible.value) {
diff --git a/src/compiler/scala/tools/nsc/typechecker/SyntheticMethods.scala b/src/compiler/scala/tools/nsc/typechecker/SyntheticMethods.scala
index 0c9ed29182..2fe8925c95 100644
--- a/src/compiler/scala/tools/nsc/typechecker/SyntheticMethods.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/SyntheticMethods.scala
@@ -63,7 +63,7 @@ trait SyntheticMethods extends ast.TreeDSL {
     // in the original order.
     def accessors = clazz.caseFieldAccessors sortBy { acc =>
       originalAccessors indexWhere { orig =>
-        (acc.name == orig.name) || (acc.name startsWith (orig.name append "$").asInstanceOf[Name]) // [Eugene] why do we need this cast?
+        (acc.name == orig.name) || (acc.name startsWith (orig.name append "$"))
       }
     }
     val arity = accessors.size
@@ -87,7 +87,7 @@ trait SyntheticMethods extends ast.TreeDSL {
     )
 
     def forwardToRuntime(method: Symbol): Tree =
-      forwardMethod(method, getMember(ScalaRunTimeModule, (method.name prepend "_").asInstanceOf[Name]))(mkThis :: _) // [Eugene] why do we need this cast?
+      forwardMethod(method, getMember(ScalaRunTimeModule, (method.name prepend "_")))(mkThis :: _)
 
     def callStaticsMethod(name: String)(args: Tree*): Tree = {
       val method = termMember(RuntimeStaticsModule, name)
diff --git a/src/compiler/scala/tools/nsc/typechecker/Tags.scala b/src/compiler/scala/tools/nsc/typechecker/Tags.scala
index d4e4100dfa..44fa9a5d7a 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Tags.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Tags.scala
@@ -26,7 +26,7 @@ trait Tags {
     /** Finds in scope or materializes a ClassTag.
      *  Should be used instead of ClassManifest every time compiler needs to persist an erasure.
      *
-     *  Once upon a time, we had an `ErasureTag` which was to `ClassTag` the same that `AbsTypeTag` is for `TypeTag`.
+     *  Once upon a time, we had an `ErasureTag` which was to `ClassTag` the same that `WeakTypeTag` is for `TypeTag`.
      *  However we found out that we don't really need this concept, so it got removed.
      *
      *  @param   pos                    Position for error reporting. Please, provide meaningful value.
@@ -43,7 +43,7 @@ trait Tags {
       resolveTag(pos, taggedTp, allowMaterialization)
     }
 
-    /** Finds in scope or materializes an AbsTypeTag (if `concrete` is false) or a TypeTag (if `concrete` is true).
+    /** Finds in scope or materializes an WeakTypeTag (if `concrete` is false) or a TypeTag (if `concrete` is true).
      *
      *  @param   pos                    Position for error reporting. Please, provide meaningful value.
      *  @param   pre                    Prefix that represents a universe this type tag will be bound to.
@@ -60,7 +60,7 @@ trait Tags {
      *           EmptyTree if `allowMaterialization` is false, and there is no array tag in scope.
      */
     def resolveTypeTag(pos: Position, pre: Type, tp: Type, concrete: Boolean, allowMaterialization: Boolean = true): Tree = {
-      val tagSym = if (concrete) TypeTagClass else AbsTypeTagClass
+      val tagSym = if (concrete) TypeTagClass else WeakTypeTagClass
       val tagTp =  if (pre == NoType) TypeRef(BaseUniverseClass.toTypeConstructor, tagSym, List(tp)) else singleType(pre, pre member tagSym.name)
       val taggedTp = appliedType(tagTp, List(tp))
       resolveTag(pos, taggedTp, allowMaterialization)
diff --git a/src/compiler/scala/tools/nsc/typechecker/TypeDiagnostics.scala b/src/compiler/scala/tools/nsc/typechecker/TypeDiagnostics.scala
index f8a5c401df..e5c0f5767c 100644
--- a/src/compiler/scala/tools/nsc/typechecker/TypeDiagnostics.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/TypeDiagnostics.scala
@@ -59,6 +59,19 @@ trait TypeDiagnostics {
    *  the map, the addendum should also be printed.
    */
   private var addendums = perRunCaches.newMap[Position, () => String]()
+  private var isTyperInPattern = false
+
+  /** Devising new ways of communicating error info out of
+   *  desperation to work on error messages.  This is used
+   *  by typedPattern to wrap its business so we can generate
+   *  a sensible error message when things go south.
+   */
+  def typingInPattern[T](body: => T): T = {
+    val saved = isTyperInPattern
+    isTyperInPattern = true
+    try body
+    finally isTyperInPattern = saved
+  }
 
   def setAddendum(pos: Position, msg: () => String) =
     if (pos != NoPosition)
@@ -138,13 +151,17 @@ trait TypeDiagnostics {
     def hasParams         = tree.tpe.paramSectionCount > 0
     def preResultString   = if (hasParams) ": " else " of type "
 
-    def nullMessage       = "expression of type " + tree.tpe
-    def overloadedMessage = "overloaded method " + sym + " with alternatives:\n" + alternativesString(tree)
+    def patternMessage    = "pattern " + tree.tpe.finalResultType + valueParamsString(tree.tpe)
+    def exprMessage       = "expression of type " + tree.tpe
+    def overloadedMessage = s"overloaded method $sym with alternatives:\n" + alternativesString(tree)
     def moduleMessage     = "" + sym
     def defaultMessage    = moduleMessage + preResultString + tree.tpe
     def applyMessage      = defaultMessage + tree.symbol.locationString
 
-    if (sym == null) nullMessage
+    if ((sym eq null) || (sym eq NoSymbol)) {
+      if (isTyperInPattern) patternMessage
+      else exprMessage
+    }
     else if (sym.isOverloaded) overloadedMessage
     else if (sym.isModule) moduleMessage
     else if (sym.name == nme.apply) applyMessage
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index 87937519fc..a58d73bd69 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -13,10 +13,9 @@ package scala.tools.nsc
 package typechecker
 
 import scala.collection.mutable
-import scala.reflect.internal.util.BatchSourceFile
+import scala.reflect.internal.util.{ BatchSourceFile, Statistics }
 import mutable.ListBuffer
 import symtab.Flags._
-import reflect.internal.util.Statistics
 
 // Suggestion check whether we can do without priming scopes with symbols of outer scopes,
 // like the IDE does.
@@ -779,7 +778,7 @@ trait Typers extends Modes with Adaptations with Tags {
             var raw = featureDesc + " " + req + " be enabled\n" +
               "by making the implicit value language." + featureName + " visible."
             if (!(currentRun.reportedFeature contains featureTrait))
-              raw += "\nThis can be achieved by adding the import clause 'import language." + featureName + "'\n" +
+              raw += "\nThis can be achieved by adding the import clause 'import scala.language." + featureName + "'\n" +
                 "or by setting the compiler option -language:" + featureName + ".\n" +
                 "See the Scala docs for value scala.language." + featureName + " for a discussion\n" +
                 "why the feature " + req + " be explicitly enabled."
@@ -1405,14 +1404,15 @@ trait Typers extends Modes with Adaptations with Tags {
             unit.error(clazz.pos, "value class needs to have exactly one public val parameter")
         }
       }
-      body foreach {
-        case md: ModuleDef =>
-          unit.error(md.pos, "value class may not have nested module definitions")
-        case cd: ClassDef =>
-          unit.error(cd.pos, "value class may not have nested class definitions")
-        case md: DefDef if md.symbol.isConstructor && !md.symbol.isPrimaryConstructor =>
-          unit.error(md.pos, "value class may not have secondary constructors")
-        case _ =>
+
+      def valueClassMayNotHave(at: Tree, what: String) = unit.error(at.pos, s"value class may not have $what")
+      body.foreach {
+        case dd: DefDef if dd.symbol.isAuxiliaryConstructor => valueClassMayNotHave(dd, "secondary constructors")
+        case t => t.foreach {
+          case md: ModuleDef => valueClassMayNotHave(md, "nested module definitions")
+          case cd: ClassDef  => valueClassMayNotHave(cd, "nested class definitions")
+          case _             =>
+        }
       }
       for (tparam <- clazz.typeParams)
         if (tparam hasAnnotation definitions.SpecializedClass)
@@ -1577,6 +1577,12 @@ trait Typers extends Modes with Adaptations with Tags {
           if (psym.isFinal)
             pending += ParentFinalInheritanceError(parent, psym)
 
+          if (psym.hasDeprecatedInheritanceAnnotation) {
+            val suffix = psym.deprecatedInheritanceMessage map (": " + _) getOrElse ""
+            val msg = s"inheritance from ${psym.fullLocationString} is deprecated$suffix"
+            unit.deprecationWarning(parent.pos, msg)
+          }
+
           if (psym.isSealed && !phase.erasedTypes)
             if (context.unit.source.file == psym.sourceFile)
               psym addChild context.owner
@@ -1868,7 +1874,7 @@ trait Typers extends Modes with Adaptations with Tags {
      *  @param rhs      ...
      */
     def computeParamAliases(clazz: Symbol, vparamss: List[List[ValDef]], rhs: Tree) {
-      log("computing param aliases for "+clazz+":"+clazz.primaryConstructor.tpe+":"+rhs)//debug
+      debuglog(s"computing param aliases for $clazz:${clazz.primaryConstructor.tpe}:$rhs")
       def decompose(call: Tree): (Tree, List[Tree]) = call match {
         case Apply(fn, args) =>
           val (superConstr, args1) = decompose(fn)
@@ -2392,7 +2398,7 @@ trait Typers extends Modes with Adaptations with Tags {
         else targs.init
 
       def mkParams(methodSym: Symbol, formals: List[Type] = deriveFormals) =
-        if (formals.isEmpty) { MissingParameterTypeAnonMatchError(tree, pt); Nil }
+        if (formals.isEmpty || !formals.forall(isFullyDefined)) { MissingParameterTypeAnonMatchError(tree, pt); Nil }
         else methodSym newSyntheticValueParams formals
 
       def mkSel(params: List[Symbol]) =
@@ -3227,7 +3233,7 @@ trait Typers extends Modes with Adaptations with Tags {
         val nbSubPats = args.length
 
         val (formals, formalsExpanded) = extractorFormalTypes(resTp, nbSubPats, fun1.symbol)
-        if (formals == null) duplErrorTree(WrongNumberArgsPatternError(tree, fun))
+        if (formals == null) duplErrorTree(WrongNumberOfArgsError(tree, fun))
         else {
           val args1 = typedArgs(args, mode, formals, formalsExpanded)
           // This used to be the following (failing) assert:
@@ -3434,7 +3440,7 @@ trait Typers extends Modes with Adaptations with Tags {
             }
 
             if (hasError) annotationError
-            else AnnotationInfo(annType, List(), nvPairs map {p => (p._1.asInstanceOf[Name], p._2.get)}).setOriginal(Apply(typedFun, args).setPos(ann.pos)) // [Eugene] why do we need this cast?
+            else AnnotationInfo(annType, List(), nvPairs map {p => (p._1, p._2.get)}).setOriginal(Apply(typedFun, args).setPos(ann.pos))
           }
         } else if (requireJava) {
           reportAnnotationError(NestedAnnotationError(ann, annType))
@@ -3813,18 +3819,23 @@ trait Typers extends Modes with Adaptations with Tags {
        *  - simplest solution: have two method calls
        *
        */
-      def mkInvoke(cxTree: Tree, tree: Tree, qual: Tree, name: Name): Option[Tree] =
+      def mkInvoke(cxTree: Tree, tree: Tree, qual: Tree, name: Name): Option[Tree] = {
+        debuglog(s"mkInvoke($cxTree, $tree, $qual, $name)")
         acceptsApplyDynamicWithType(qual, name) map { tp =>
           // tp eq NoType => can call xxxDynamic, but not passing any type args (unless specified explicitly by the user)
           // in scala-virtualized, when not NoType, tp is passed as type argument (for selection on a staged Struct)
 
-          // strip off type application -- we're not doing much with outer, so don't bother preserving cxTree's attributes etc
-          val (outer, explicitTargs) = cxTree match {
-              case TypeApply(fun, targs) => (fun, targs)
-              case Apply(TypeApply(fun, targs), args) => (Apply(fun, args), targs)
-              case t => (t, Nil)
+          // strip off type application -- we're not doing much with outer,
+          // so don't bother preserving cxTree's attributes etc
+          val cxTree1 = cxTree match {
+            case t: ValOrDefDef => t.rhs
+            case t              => t
+          }
+          val (outer, explicitTargs) = cxTree1 match {
+            case TypeApply(fun, targs)              => (fun, targs)
+            case Apply(TypeApply(fun, targs), args) => (Apply(fun, args), targs)
+            case t                                  => (t, Nil)
           }
-
           @inline def hasNamedArg(as: List[Tree]) = as.collectFirst{case AssignOrNamedArg(lhs, rhs) =>}.nonEmpty
 
           // note: context.tree includes at most one Apply node
@@ -3849,6 +3860,7 @@ trait Typers extends Modes with Adaptations with Tags {
 
           atPos(qual.pos)(Apply(tappSel, List(Literal(Constant(name.decode)))))
         }
+      }
     }
 
     @inline final def deindentTyping() = context.typingIndentLevel -= 2
@@ -4069,7 +4081,7 @@ trait Typers extends Modes with Adaptations with Tags {
             if ( !settings.XoldPatmat.value && !isPastTyper
               && thenp1.tpe.annotations.isEmpty && elsep1.tpe.annotations.isEmpty // annotated types need to be lubbed regardless (at least, continations break if you by pass them like this)
               && thenTp =:= elseTp
-               ) (thenp1.tpe, false) // use unpacked type
+               ) (thenp1.tpe.deconst, false) // use unpacked type. Important to deconst, as is done in ptOrLub, otherwise `if (???) 0 else 0` evaluates to 0 (SI-6331)
             // TODO: skolemize (lub of packed types) when that no longer crashes on files/pos/t4070b.scala
             else ptOrLub(thenp1.tpe :: elsep1.tpe :: Nil, pt)
 
@@ -5454,7 +5466,7 @@ trait Typers extends Modes with Adaptations with Tags {
       // as a compromise, context.enrichmentEnabled tells adaptToMember to go ahead and enrich,
       // but arbitrary conversions (in adapt) are disabled
       // TODO: can we achieve the pattern matching bit of the string interpolation SIP without this?
-      context.withImplicitsDisabledAllowEnrichment(typed(tree, PATTERNmode, pt))
+      typingInPattern(context.withImplicitsDisabledAllowEnrichment(typed(tree, PATTERNmode, pt)))
     }
 
     /** Types a (fully parameterized) type tree */
@@ -5559,8 +5571,8 @@ trait Typers extends Modes with Adaptations with Tags {
 }
 
 object TypersStats {
-  import reflect.internal.TypesStats._
-  import reflect.internal.BaseTypeSeqsStats._
+  import scala.reflect.internal.TypesStats._
+  import scala.reflect.internal.BaseTypeSeqsStats._
   val typedIdentCount     = Statistics.newCounter("#typechecked identifiers")
   val typedSelectCount    = Statistics.newCounter("#typechecked selections")
   val typedApplyCount     = Statistics.newCounter("#typechecked applications")