From 5e4c47f33b8e25feb59ab4599231b1b8d3150de8 Mon Sep 17 00:00:00 2001
From: Eugene Burmako <xeno.by@gmail.com>
Date: Sat, 14 Apr 2012 21:11:37 +0200
Subject: implements reification of tough types

---
 src/compiler/scala/reflect/internal/StdNames.scala |   1 +
 src/compiler/scala/reflect/internal/Symbols.scala  |   4 +-
 src/compiler/scala/reflect/internal/TreeInfo.scala |  16 +--
 src/compiler/scala/reflect/internal/Types.scala    |  33 ++++-
 .../reflect/reify/codegen/AnnotationInfos.scala    |  56 ++++++++
 .../scala/reflect/reify/codegen/Symbols.scala      | 114 +++++++++++++----
 .../scala/reflect/reify/codegen/Trees.scala        |  20 ++-
 .../scala/reflect/reify/codegen/Types.scala        | 141 ++++++---------------
 .../scala/reflect/reify/phases/Metalevels.scala    |   2 +
 .../scala/reflect/reify/phases/Reify.scala         |   4 +
 src/compiler/scala/tools/nsc/util/Position.scala   |  10 +-
 src/library/scala/reflect/api/Attachment.scala     |  10 +-
 src/library/scala/reflect/api/StandardNames.scala  |   1 +
 src/library/scala/reflect/api/Symbols.scala        |   5 +
 src/library/scala/reflect/api/Trees.scala          |  18 ++-
 src/library/scala/reflect/api/TypeTags.scala       |   7 +-
 src/library/scala/reflect/api/Types.scala          |   4 +
 17 files changed, 296 insertions(+), 150 deletions(-)
 create mode 100644 src/compiler/scala/reflect/reify/codegen/AnnotationInfos.scala

(limited to 'src')

diff --git a/src/compiler/scala/reflect/internal/StdNames.scala b/src/compiler/scala/reflect/internal/StdNames.scala
index ac2cf178bf..bf468affe6 100644
--- a/src/compiler/scala/reflect/internal/StdNames.scala
+++ b/src/compiler/scala/reflect/internal/StdNames.scala
@@ -206,6 +206,7 @@ trait StdNames extends NameManglers { self: SymbolTable =>
     val MIRROR_FREE_PREFIX: NameType        = "free$"
     val MIRROR_FREE_THIS_SUFFIX: NameType   = "$this"
     val MIRROR_FREE_VALUE_SUFFIX: NameType  = "$value"
+    val MIRROR_SYMDEF_PREFIX: NameType      = "symdef$"
     val MIXIN_CONSTRUCTOR: NameType         = "$init$"
     val MODULE_INSTANCE_FIELD: NameType     = NameTransformer.MODULE_INSTANCE_NAME  // "MODULE$"
     val OUTER: NameType                     = "$outer"
diff --git a/src/compiler/scala/reflect/internal/Symbols.scala b/src/compiler/scala/reflect/internal/Symbols.scala
index 3bb57cea04..c9947c3c09 100644
--- a/src/compiler/scala/reflect/internal/Symbols.scala
+++ b/src/compiler/scala/reflect/internal/Symbols.scala
@@ -64,6 +64,7 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     this: Symbol =>
 
     def kind: String = kindString
+    def isExistential: Boolean = this.isExistentiallyBound
 
     def newNestedSymbol(name: Name, pos: Position, newFlags: Long, isClass: Boolean): Symbol = name match {
       case n: TermName => newTermSymbol(n, pos, newFlags)
@@ -897,8 +898,10 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
 
       if (!owner.isLocatable) return false
       if (owner.isTerm) return false
+      if (isLocalDummy) return false
 
       if (isType && isNonClassType) return false
+      if (isRefinementClass) return false
       return true
     }
 
@@ -2965,7 +2968,6 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     override def isFreeTerm = true
   }
 
-  // [Eugene] the NoSymbol origin works for type parameters. what about existential free types?
   class FreeType(name0: TypeName, value0: => Any, val origin: String) extends TypeSkolem(NoSymbol, NoPosition, name0, NoSymbol) {
     def value = value0
     override def isFreeType = true
diff --git a/src/compiler/scala/reflect/internal/TreeInfo.scala b/src/compiler/scala/reflect/internal/TreeInfo.scala
index a8cca1625f..039c8e557a 100644
--- a/src/compiler/scala/reflect/internal/TreeInfo.scala
+++ b/src/compiler/scala/reflect/internal/TreeInfo.scala
@@ -590,7 +590,7 @@ abstract class TreeInfo {
   }
 
   object Reified {
-    def unapply(tree: Tree): Option[(Tree, List[ValDef], Tree)] = tree match {
+    def unapply(tree: Tree): Option[(Tree, List[Tree], Tree)] = tree match {
       case ReifiedTree(reifee, symbolTable, reified, _) =>
         Some(reifee, symbolTable, reified)
       case ReifiedType(reifee, symbolTable, reified) =>
@@ -601,16 +601,16 @@ abstract class TreeInfo {
   }
 
   object ReifiedTree {
-    def unapply(tree: Tree): Option[(Tree, List[ValDef], Tree, Tree)] = tree match {
+    def unapply(tree: Tree): Option[(Tree, List[Tree], Tree, Tree)] = tree match {
       case reifee @ Block((mrDef @ ValDef(_, _, _, _)) :: symbolTable, Apply(Apply(_, List(tree)), List(Apply(_, List(tpe))))) if mrDef.name == nme.MIRROR_SHORT =>
-        Some(reifee, symbolTable map (_.asInstanceOf[ValDef]), tree, tpe)
+        Some(reifee, symbolTable, tree, tpe)
       case _ =>
         None
     }
   }
 
   object InlineableTreeSplice {
-    def unapply(tree: Tree): Option[(Tree, List[ValDef], Tree, Tree, Symbol)] = tree match {
+    def unapply(tree: Tree): Option[(Tree, List[Tree], Tree, Tree, Symbol)] = tree match {
       case select @ Select(ReifiedTree(splicee, symbolTable, tree, tpe), _) if select.symbol == ExprEval || select.symbol == ExprValue =>
         Some(splicee, symbolTable, tree, tpe, select.symbol)
       case _ =>
@@ -619,7 +619,7 @@ abstract class TreeInfo {
   }
 
   object InlinedTreeSplice {
-    def unapply(tree: Tree): Option[(Tree, List[ValDef], Tree, Tree)] = tree match {
+    def unapply(tree: Tree): Option[(Tree, List[Tree], Tree, Tree)] = tree match {
       case Select(ReifiedTree(splicee, symbolTable, tree, tpe), name) if name == ExprTree.name =>
         Some(splicee, symbolTable, tree, tpe)
       case _ =>
@@ -628,16 +628,16 @@ abstract class TreeInfo {
   }
 
   object ReifiedType {
-    def unapply(tree: Tree): Option[(Tree, List[ValDef], Tree)] = tree match {
+    def unapply(tree: Tree): Option[(Tree, List[Tree], Tree)] = tree match {
       case reifee @ Block((mrDef @ ValDef(_, _, _, _)) :: symbolTable, Apply(_, List(tpe))) if mrDef.name == nme.MIRROR_SHORT =>
-        Some(reifee, symbolTable map (_.asInstanceOf[ValDef]), tpe)
+        Some(reifee, symbolTable, tpe)
       case _ =>
         None
     }
   }
 
   object InlinedTypeSplice {
-    def unapply(tree: Tree): Option[(Tree, List[ValDef], Tree)] = tree match {
+    def unapply(tree: Tree): Option[(Tree, List[Tree], Tree)] = tree match {
       case Select(ReifiedType(splicee, symbolTable, tpe), name) if name == TypeTagTpe.name =>
         Some(splicee, symbolTable, tpe)
       case _ =>
diff --git a/src/compiler/scala/reflect/internal/Types.scala b/src/compiler/scala/reflect/internal/Types.scala
index 3efbe4b4df..d7c90d597c 100644
--- a/src/compiler/scala/reflect/internal/Types.scala
+++ b/src/compiler/scala/reflect/internal/Types.scala
@@ -266,6 +266,35 @@ trait Types extends api.Types { self: SymbolTable =>
     def typeArguments = typeArgs
     def erasure = transformedType(this)
     def substituteTypes(from: List[Symbol], to: List[Type]): Type = subst(from, to)
+
+    // [Eugene] to be discussed and refactored
+    def isConcrete = {
+      def notConcreteSym(sym: Symbol) =
+        sym.isAbstractType && !sym.isExistential
+
+      def notConcreteTpe(tpe: Type): Boolean = tpe match {
+        case ThisType(_) => false
+        case SuperType(_, _) => false
+        case SingleType(pre, sym) => notConcreteSym(sym)
+        case ConstantType(_) => false
+        case TypeRef(_, sym, _) => notConcreteSym(sym)
+        case RefinedType(_, _) => false
+        case ExistentialType(_, _) => false
+        case AnnotatedType(_, tp, _) => notConcreteTpe(tp)
+        case _ => true
+      }
+
+      !notConcreteTpe(this)
+    }
+
+    // [Eugene] is this comprehensive?
+    // the only thingies that we want to splice are: 1) type parameters, 2) type members
+    // the thingies that we don't want to splice are: 1) concrete types (obviously), 2) existential skolems
+    // this check seems to cover them all, right?
+    // todo. after we discuss this, move the check to subclasses
+    def isSpliceable = {
+      this.isInstanceOf[TypeRef] && typeSymbol.isAbstractType && !typeSymbol.isExistential
+    }
   }
 
   /** The base class for all types */
@@ -2147,7 +2176,7 @@ trait Types extends api.Types { self: SymbolTable =>
          sym.isPackageClass
       || pre.isGround && args.forall(_.isGround)
     )
-    
+
     def etaExpand: Type = {
       // must initialise symbol, see test/files/pos/ticket0137.scala
       val tpars = initializedTypeParams
@@ -2763,7 +2792,7 @@ trait Types extends api.Types { self: SymbolTable =>
       zippedArgs map { case (p, a) => p.name + "=" + a } mkString (origin + "[", ", ", "]")
     )
   }
-  
+
   trait UntouchableTypeVar extends TypeVar {
     override def untouchable = true
     override def isGround = true
diff --git a/src/compiler/scala/reflect/reify/codegen/AnnotationInfos.scala b/src/compiler/scala/reflect/reify/codegen/AnnotationInfos.scala
new file mode 100644
index 0000000000..1d218317dc
--- /dev/null
+++ b/src/compiler/scala/reflect/reify/codegen/AnnotationInfos.scala
@@ -0,0 +1,56 @@
+package scala.reflect.reify
+package codegen
+
+trait AnnotationInfos {
+  self: Reifier =>
+
+  import mirror._
+  import definitions._
+  import treeInfo._
+
+  // usually annotations are reified as their originals from Modifiers
+  // however, when reifying free and tough types, we're forced to reify annotation infos as is
+  // why is that bad? take a look inside
+  def reifyAnnotationInfo(ann: AnnotationInfo): Tree = {
+    val reifiedArgs = ann.args map { arg =>
+      val saved1 = reifyTreeSymbols
+      val saved2 = reifyTreeTypes
+
+      try {
+        // one more quirk of reifying annotations
+        //
+        // when reifying AnnotatedTypes we need to reify all the types and symbols of inner ASTs
+        // that's because a lot of logic expects post-typer trees to have non-null tpes
+        //
+        // Q: reified trees are pre-typer, so there's shouldn't be a problem.
+        //    reflective typechecker will fill in missing symbols and types, right?
+        // A: actually, no. annotation ASTs live inside AnnotatedTypes,
+        //    and insides of the types is the place where typechecker doesn't look.
+        reifyTreeSymbols = true
+        reifyTreeTypes = true
+
+        // todo. every AnnotationInfo is an island, entire of itself
+        // no regular Traverser or Transformer can reach it
+        // hence we need to run its contents through the entire reification pipeline
+        // e.g. to apply reshaping or to check metalevels
+        reify(arg)
+      } finally {
+        reifyTreeSymbols = saved1
+        reifyTreeTypes = saved2
+      }
+    }
+
+    def reifyClassfileAnnotArg(arg: ClassfileAnnotArg): Tree = arg match {
+      case LiteralAnnotArg(const) =>
+        mirrorFactoryCall(nme.LiteralAnnotArg, reifyProduct(const))
+      case ArrayAnnotArg(args) =>
+        mirrorFactoryCall(nme.ArrayAnnotArg, scalaFactoryCall(nme.Array, args map reifyClassfileAnnotArg: _*))
+      case NestedAnnotArg(ann) =>
+        mirrorFactoryCall(nme.NestedAnnotArg, reifyAnnotationInfo(ann))
+    }
+
+    // if you reify originals of anns, you get SO when trying to reify AnnotatedTypes, so screw it - after all, it's not that important
+    val reifiedAssocs = ann.assocs map (assoc => scalaFactoryCall(nme.Tuple2, reify(assoc._1), reifyClassfileAnnotArg(assoc._2)))
+    mirrorFactoryCall(nme.AnnotationInfo, reify(ann.atp), mkList(reifiedArgs), mkList(reifiedAssocs))
+  }
+}
\ No newline at end of file
diff --git a/src/compiler/scala/reflect/reify/codegen/Symbols.scala b/src/compiler/scala/reflect/reify/codegen/Symbols.scala
index 3328f5e402..2fc0002838 100644
--- a/src/compiler/scala/reflect/reify/codegen/Symbols.scala
+++ b/src/compiler/scala/reflect/reify/codegen/Symbols.scala
@@ -46,13 +46,8 @@ trait Symbols {
       }
     } else {
       // todo. make sure that free methods and free local defs work correctly
-      if (sym.isTerm) {
-        if (reifyDebug) println("Free term" + (if (sym.isCapturedVariable) " (captured)" else "") + ": " + sym)
-        reifyFreeTerm(sym, Ident(sym))
-      } else {
-        if (reifyDebug) println("Free type: " + sym)
-        reifyFreeType(sym, Ident(sym))
-      }
+      if (sym.isTerm) reifyFreeTerm(sym, Ident(sym))
+      else reifyFreeType(sym, Ident(sym))
     }
   }
 
@@ -61,13 +56,16 @@ trait Symbols {
       case Some(reified) =>
         reified
       case None =>
+        if (reifyDebug) println("Free term" + (if (sym.isCapturedVariable) " (captured)" else "") + ": " + sym + "(" + sym.accurateKindString + ")")
+        var name = newTermName(nme.MIRROR_FREE_PREFIX + sym.name)
+        if (sym.isType) name = name.append(nme.MIRROR_FREE_THIS_SUFFIX)
         if (sym.isCapturedVariable) {
           assert(value.isInstanceOf[Ident], showRaw(value))
           val capturedTpe = capturedVariableType(sym)
           val capturedValue = referenceCapturedVariable(sym)
-          locallyReify(sym, mirrorCall(nme.newFreeTerm, reify(sym.name.toString), reify(capturedTpe), capturedValue, reify(origin(sym))))
+          locallyReify(sym, name, mirrorCall(nme.newFreeTerm, reify(sym.name.toString), reify(capturedTpe), capturedValue, reify(origin(sym))))
         } else {
-          locallyReify(sym, mirrorCall(nme.newFreeTerm, reify(sym.name.toString), reify(sym.tpe), value, reify(origin(sym))))
+          locallyReify(sym, name, mirrorCall(nme.newFreeTerm, reify(sym.name.toString), reify(sym.tpe), value, reify(origin(sym))))
         }
     }
 
@@ -76,36 +74,104 @@ trait Symbols {
       case Some(reified) =>
         reified
       case None =>
+        if (reifyDebug) println("Free type: %s (%s)".format(sym, sym.accurateKindString))
+        var name = newTermName(nme.MIRROR_FREE_PREFIX + sym.name)
         val phantomTypeTag = Apply(TypeApply(Select(Ident(nme.MIRROR_SHORT), nme.TypeTag), List(value)), List(Literal(Constant(null))))
         // todo. implement info reification for free types: type bounds, HK-arity, whatever else that can be useful
-        locallyReify(sym, mirrorCall(nme.newFreeType, reify(sym.name.toString), reify(sym.info), phantomTypeTag, reify(origin(sym))))
+        locallyReify(sym, name, mirrorCall(nme.newFreeType, reify(sym.name.toString), reify(sym.info), phantomTypeTag, reify(origin(sym))))
+    }
+
+  def reifySymDef(sym: Symbol): Tree =
+    locallyReified get sym match {
+      case Some(reified) =>
+        reified
+      case None =>
+        if (reifyDebug) println("Sym def: %s (%s)".format(sym, sym.accurateKindString))
+        assert(!sym.isLocatable, sym) // if this assertion fires, then tough type reification needs to be rethought
+        sym.owner.ownersIterator find (!_.isLocatable) foreach reifySymDef
+        var name = newTermName(nme.MIRROR_SYMDEF_PREFIX + sym.name)
+        locallyReify(sym, name, Apply(Select(reify(sym.owner), nme.newNestedSymbol), List(reify(sym.name), reify(sym.pos), reify(sym.flags), reify(sym.isClass))))
     }
 
+  // todo. very brittle abstraction, needs encapsulation
   import scala.collection.mutable._
-  private val localReifications = ArrayBuffer[ValDef]()
+  private val localReifications = ArrayBuffer[Tree]()
   private val locallyReified = Map[Symbol, Tree]()
-  def symbolTable: List[ValDef] = localReifications.toList
-  def symbolTable_=(newSymbolTable: List[ValDef]): Unit = {
+  private var filledIn = false
+  def symbolTable: List[Tree] = { fillInSymbolTable(); localReifications.toList }
+  def symbolTable_=(newSymbolTable: List[Tree]): Unit = {
     localReifications.clear()
     locallyReified.clear()
+    filledIn = false
     newSymbolTable foreach {
-      case freedef @ FreeDef(_, name, binding, _) =>
-        if (!(locallyReified contains binding.symbol)) {
-          localReifications += freedef
-          locallyReified(binding.symbol) = Ident(name)
+      case entry =>
+        val att = entry.attachment
+        att match {
+          case sym: Symbol =>
+            // don't duplicate reified symbols when merging inlined reifee
+            if (!(locallyReified contains sym)) {
+              val ValDef(_, name, _, _) = entry
+              localReifications += entry
+              locallyReified(sym) = Ident(name)
+            }
+          case other =>
+            // do nothing => symbol table fill-ins will be repopulated later
         }
     }
   }
 
-  private def locallyReify(sym: Symbol, reificode: => Tree): Tree = {
+  private def localName(name0: TermName): TermName = {
+    var name = name0.toString
+    name = name.replace(".type", "$type")
+    name = name.replace(" ", "$")
+    val fresh = typer.context.unit.fresh
+    newTermName(fresh.newName(name))
+  }
+
+  private def locallyReify(sym: Symbol, name0: TermName, reificode: => Tree): Tree = {
     val reified = reificode
-    val Apply(Select(_, flavor), _) = reified
-    // [Eugene] name clashes are impossible, right?
-    var name = newTermName(nme.MIRROR_FREE_PREFIX + sym.name)
-    if (flavor == nme.newFreeTerm && sym.isType) name = name.append(nme.MIRROR_FREE_THIS_SUFFIX);
-    // todo. also reify annotations for free vars
-    localReifications += ValDef(NoMods, name, TypeTree(), reified)
+    val name = localName(name0)
+    // todo. tried to declare a private class here to carry an attachment, but it's path-dependent
+    // so got troubles with exchanging free variables between nested and enclosing quasiquotes
+    // attaching just Symbol isn't good either, so we need to think of a principled solution
+    val local = ValDef(NoMods, name, TypeTree(), reified) setAttachment sym
+    localReifications += local
+    filledIn = false
     locallyReified(sym) = Ident(name)
     locallyReified(sym)
   }
+
+  /** Sets type signatures and annotations for locally reified symbols */
+  private def fillInSymbolTable() = {
+    if (!filledIn) {
+      val fillIns = new ArrayBuffer[Tree]
+      var i = 0
+      while (i < localReifications.length) {
+        // fillInSymbol might create new locallyReified symbols, that's why this is done iteratively
+        val reified = localReifications(i)
+        reified.attachment match {
+          case sym: Symbol => fillIns += fillInSymbol(sym)
+          case other => // do nothing
+        }
+        i += 1
+      }
+
+      filledIn = true
+      localReifications ++= fillIns.toList
+    }
+  }
+
+  /** Generate code to add type and annotation info to a reified symbol */
+  private def fillInSymbol(sym: Symbol): Tree = {
+    if (reifyDebug) println("Filling in: %s (%s)".format(sym, sym.accurateKindString))
+    val isFree = locallyReified(sym) match { case Ident(name) => name startsWith nme.MIRROR_FREE_PREFIX }
+    if (isFree) {
+      if (sym.annotations.isEmpty) EmptyTree
+      else Apply(Select(locallyReified(sym), nme.setAnnotations), List(reify(sym.annotations)))
+    } else {
+      val rset = Apply(Select(locallyReified(sym), nme.setTypeSignature), List(reifyType(sym.info)))
+      if (sym.annotations.isEmpty) rset
+      else Apply(Select(rset, nme.setAnnotations), List(reify(sym.annotations)))
+    }
+  }
 }
\ No newline at end of file
diff --git a/src/compiler/scala/reflect/reify/codegen/Trees.scala b/src/compiler/scala/reflect/reify/codegen/Trees.scala
index 22f42aea49..5ad53c0009 100644
--- a/src/compiler/scala/reflect/reify/codegen/Trees.scala
+++ b/src/compiler/scala/reflect/reify/codegen/Trees.scala
@@ -8,6 +8,11 @@ trait Trees {
   import definitions._
   import treeInfo._
 
+  // unfortunately, these are necessary to reify AnnotatedTypes
+  // I'd gladly got rid of them, but I don't fancy making a metaprogramming API that doesn't work with annotated types
+  var reifyTreeSymbols = false
+  var reifyTreeTypes = false
+
   /**
    *  Reify a tree.
    *  For internal use only, use ``reified'' instead.
@@ -59,6 +64,17 @@ trait Trees {
         reifyProduct(tree)
     }
 
+    // usually we don't reify symbols/types, because they can be re-inferred during subsequent reflective compilation
+    // however, reification of AnnotatedTypes is special. see ``reifyType'' to find out why.
+    if (reifyTreeSymbols && tree.hasSymbol) {
+      if (reifyDebug) println("reifying symbol %s for tree %s".format(tree.symbol, tree))
+      rtree = Apply(Select(rtree, nme.setSymbol), List(reifySymRef(tree.symbol)))
+    }
+    if (reifyTreeTypes && tree.tpe != null) {
+      if (reifyDebug) println("reifying type %s for tree %s".format(tree.tpe, tree))
+      rtree = Apply(Select(rtree, nme.setType), List(reifyType(tree.tpe)))
+    }
+
     rtree
   }
 
@@ -82,7 +98,7 @@ trait Trees {
             case InlinedTreeSplice(_, inlinedSymbolTable, tree, _) =>
               if (reifyDebug) println("inlining the splicee")
               // all free vars local to the enclosing reifee should've already been inlined by ``Metalevels''
-              inlinedSymbolTable foreach { case freedef @ FreeDef(_, _, binding, _) => assert(!binding.symbol.isLocalToReifee, freedef) }
+              inlinedSymbolTable collect { case freedef @ FreeDef(_, _, binding, _) if binding.symbol.isLocalToReifee => assert(false, freedef) }
               symbolTable ++= inlinedSymbolTable
               tree
             case tree =>
@@ -152,7 +168,7 @@ trait Trees {
         val tpe = tpe0.dealias
         if (reifyDebug) println("reifying bound type %s (underlying type is %s, dealiased is %s)".format(sym0, tpe0, tpe))
 
-        if (eligibleForSplicing(tpe)) {
+        if (tpe.isSpliceable) {
           val spliced = spliceType(tpe)
           if (spliced == EmptyTree) {
             if (reifyDebug) println("splicing failed: reify as is")
diff --git a/src/compiler/scala/reflect/reify/codegen/Types.scala b/src/compiler/scala/reflect/reify/codegen/Types.scala
index 9bc113e8a4..948728088e 100644
--- a/src/compiler/scala/reflect/reify/codegen/Types.scala
+++ b/src/compiler/scala/reflect/reify/codegen/Types.scala
@@ -55,11 +55,9 @@ trait Types {
       case tpe @ NullaryMethodType(restpe) =>
         reifyProduct(tpe)
       case tpe @ AnnotatedType(anns, underlying, selfsym) =>
-//        reifyAnnotatedType(tpe)
-        CannotReifyType(tpe)
+        reifyAnnotatedType(tpe)
       case _ =>
-//        reifyToughType(tpe)
-        CannotReifyType(tpe)
+        reifyToughType(tpe)
     }
   }
 
@@ -70,13 +68,6 @@ trait Types {
   var maybeConcrete = true
   var definitelyConcrete = true
 
-  def eligibleForSplicing(tpe: Type): Boolean = {
-    // [Eugene] is this comprehensive?
-    // the only thingies that we want to splice are: 1) type parameters, 2) type members
-    // this check seems to cover them all, right?
-    tpe.isInstanceOf[TypeRef] && tpe.typeSymbol.isAbstractType
-  }
-
   private type SpliceCacheKey = (Symbol, Symbol)
   private lazy val spliceCache: collection.mutable.Map[SpliceCacheKey, Tree] = {
     val cache = analyzer.perRunMacroCache.getOrElseUpdate(MacroContextReify, collection.mutable.Map[Any, Any]())
@@ -84,7 +75,7 @@ trait Types {
   }
 
   def spliceType(tpe: Type): Tree = {
-    if (eligibleForSplicing(tpe)) {
+    if (tpe.isSpliceable) {
       if (reifyDebug) println("splicing " + tpe)
 
       if (spliceTypesEnabled) {
@@ -113,7 +104,7 @@ trait Types {
               splice match {
                 case InlinedTypeSplice(_, inlinedSymbolTable, tpe) =>
                   // all free vars local to the enclosing reifee should've already been inlined by ``Metalevels''
-                  inlinedSymbolTable foreach { case freedef @ FreeDef(_, _, binding, _) => assert(!binding.symbol.isLocalToReifee, freedef) }
+                  inlinedSymbolTable collect { case freedef @ FreeDef(_, _, binding, _) if binding.symbol.isLocalToReifee => assert(false, freedef) }
                   symbolTable ++= inlinedSymbolTable
                   reifyTrace("inlined the splicee: ")(tpe)
                 case tpe =>
@@ -134,93 +125,39 @@ trait Types {
     EmptyTree
   }
 
-  // yet another thingie disabled for simplicity
-  // in principle, we could retain and reify AnnotatedTypes
-  // but that'd require reifying every type and symbol inside ann.args
-  // however, since we've given up on tough types for the moment, the former would be problematic
-//  private def reifyAnnotatedType(tpe: AnnotatedType): Tree = {
-//    // ``Reshaper'' transforms annotation infos from symbols back into Modifier.annotations, which are trees
-//    // so the only place on Earth that can lead to reification of AnnotationInfos is the Ay Tee Land
-//    // therefore this function is as local as possible, don't move it out of this scope
-//    def reifyAnnotationInfo(ann: AnnotationInfo): Tree = {
-//      val reifiedArgs = ann.args map { arg =>
-//        val saved1 = reifyTreeSymbols
-//        val saved2 = reifyTreeTypes
-//
-//        try {
-//          // one more quirk of reifying annotations
-//          //
-//          // when reifying AnnotatedTypes we need to reify all the types and symbols of inner ASTs
-//          // that's because a lot of logic expects post-typer trees to have non-null tpes
-//          //
-//          // Q: reified trees are pre-typer, so there's shouldn't be a problem.
-//          //    reflective typechecker will fill in missing symbols and types, right?
-//          // A: actually, no. annotation ASTs live inside AnnotatedTypes,
-//          //    and insides of the types is the place where typechecker doesn't look.
-//          reifyTreeSymbols = true
-//          reifyTreeTypes = true
-//
-//          // todo. every AnnotationInfo is an island, entire of itself
-//          // no regular Traverser or Transformer can reach it
-//          // hence we need to run its contents through the entire reification pipeline
-//          // e.g. to apply reshaping or to check metalevels
-//          reify(arg)
-//        } finally {
-//          reifyTreeSymbols = saved1
-//          reifyTreeTypes = saved2
-//        }
-//      }
-//
-//      def reifyClassfileAnnotArg(arg: ClassfileAnnotArg): Tree = arg match {
-//        case LiteralAnnotArg(const) =>
-//          mirrorFactoryCall(nme.LiteralAnnotArg, reifyProduct(const))
-//        case ArrayAnnotArg(args) =>
-//          mirrorFactoryCall(nme.ArrayAnnotArg, scalaFactoryCall(nme.Array, args map reifyClassfileAnnotArg: _*))
-//        case NestedAnnotArg(ann) =>
-//          mirrorFactoryCall(nme.NestedAnnotArg, reifyAnnotationInfo(ann))
-//      }
-//
-//      // if you reify originals of anns, you get SO when trying to reify AnnotatedTypes, so screw it - after all, it's not that important
-//      val reifiedAssocs = ann.assocs map (assoc => scalaFactoryCall(nme.Tuple2, reify(assoc._1), reifyClassfileAnnotArg(assoc._2)))
-//      mirrorFactoryCall(nme.AnnotationInfo, reify(ann.atp), mkList(reifiedArgs), mkList(reifiedAssocs))
-//    }
-//
-//    val AnnotatedType(anns, underlying, selfsym) = tpe
-//    mirrorFactoryCall(nme.AnnotatedType, mkList(anns map reifyAnnotationInfo), reify(underlying), reify(selfsym))
-//  }
-
-  // previous solution to reifying tough types involved creating dummy symbols (see ``registerReifiableSymbol'' calls below)
-  // however such symbols lost all the connections with their origins and became almost useless, except for typechecking
-  // hence this approach was replaced by less powerful, but more principled one based on ``reifyFreeType''
-  // it's possible that later on we will revise and revive ``reifyToughType'', but for now it's disabled under an implementation restriction
-//  /** Reify a tough type, i.e. the one that leads to creation of auxiliary symbols */
-//  // This is the uncharted territory in the reifier
-//  private def reifyToughType(tpe: Type): Tree = {
-//    if (reifyDebug) println("tough type: %s (%s)".format(tpe, tpe.kind))
-//
-//    def reifyScope(scope: Scope): Tree = {
-//      scope foreach registerReifiableSymbol
-//      mirrorCall(nme.newScopeWith, scope.toList map reify: _*)
-//    }
-//
-//    tpe match {
-//      case tpe @ RefinedType(parents, decls) =>
-//        registerReifiableSymbol(tpe.typeSymbol)
-//        mirrorFactoryCall(tpe, reify(parents), reifyScope(decls), reify(tpe.typeSymbol))
-//      case tpe @ ExistentialType(tparams, underlying) =>
-//        tparams foreach registerReifiableSymbol
-//        mirrorFactoryCall(tpe, reify(tparams), reify(underlying))
-//      case tpe @ ClassInfoType(parents, decls, clazz) =>
-//        registerReifiableSymbol(clazz)
-//        mirrorFactoryCall(tpe, reify(parents), reifyScope(decls), reify(tpe.typeSymbol))
-//      case tpe @ MethodType(params, restpe) =>
-//        params foreach registerReifiableSymbol
-//        mirrorFactoryCall(tpe, reify(params), reify(restpe))
-//      case tpe @ PolyType(tparams, underlying) =>
-//        tparams foreach registerReifiableSymbol
-//        mirrorFactoryCall(tpe, reify(tparams), reify(underlying))
-//      case _ =>
-//        throw new Error("internal error: %s (%s) is not supported".format(tpe, tpe.kind))
-//    }
-//  }
+  /** Reify an annotated type, i.e. the one that makes us deal with AnnotationInfos */
+  private def reifyAnnotatedType(tpe: AnnotatedType): Tree = {
+    val AnnotatedType(anns, underlying, selfsym) = tpe
+    mirrorFactoryCall(nme.AnnotatedType, mkList(anns map reifyAnnotationInfo), reify(underlying), reify(selfsym))
+  }
+
+  /** Reify a tough type, i.e. the one that leads to creation of auxiliary symbols */
+  private def reifyToughType(tpe: Type): Tree = {
+    if (reifyDebug) println("tough type: %s (%s)".format(tpe, tpe.kind))
+
+    def reifyScope(scope: Scope): Tree = {
+      scope foreach reifySymDef
+      mirrorCall(nme.newScopeWith, scope.toList map reify: _*)
+    }
+
+    tpe match {
+      case tpe @ RefinedType(parents, decls) =>
+        reifySymDef(tpe.typeSymbol)
+        mirrorFactoryCall(tpe, reify(parents), reifyScope(decls), reify(tpe.typeSymbol))
+      case tpe @ ExistentialType(tparams, underlying) =>
+        tparams foreach reifySymDef
+        mirrorFactoryCall(tpe, reify(tparams), reify(underlying))
+      case tpe @ ClassInfoType(parents, decls, clazz) =>
+        reifySymDef(clazz)
+        mirrorFactoryCall(tpe, reify(parents), reifyScope(decls), reify(tpe.typeSymbol))
+      case tpe @ MethodType(params, restpe) =>
+        params foreach reifySymDef
+        mirrorFactoryCall(tpe, reify(params), reify(restpe))
+      case tpe @ PolyType(tparams, underlying) =>
+        tparams foreach reifySymDef
+        mirrorFactoryCall(tpe, reify(tparams), reify(underlying))
+      case _ =>
+        throw new Error("internal error: %s (%s) is not supported".format(tpe, tpe.kind))
+    }
+  }
 }
\ No newline at end of file
diff --git a/src/compiler/scala/reflect/reify/phases/Metalevels.scala b/src/compiler/scala/reflect/reify/phases/Metalevels.scala
index a329a1043d..bb0b8ac138 100644
--- a/src/compiler/scala/reflect/reify/phases/Metalevels.scala
+++ b/src/compiler/scala/reflect/reify/phases/Metalevels.scala
@@ -134,6 +134,8 @@ trait Metalevels {
       // FreeRef(_, _) check won't work, because metalevels of symbol table and body are different, hence, freerefs in symbol table look different from freerefs in body
       // todo. also perform garbage collection on local symbols
       // so that local symbols used only in type signatures of free vars get removed
+      // todo. same goes for auxiliary symbol defs reified to support tough types
+      // some of them need to be rebuilt, some of them need to be removed, because they're no longer necessary
       case FreeRef(mr, name) if freedefsToInline contains name =>
         if (reifyDebug) println("inlineable free ref: %s in %s".format(name, showRaw(tree)))
         val freedef @ FreeDef(_, _, binding, _) = freedefsToInline(name)
diff --git a/src/compiler/scala/reflect/reify/phases/Reify.scala b/src/compiler/scala/reflect/reify/phases/Reify.scala
index f6d6423605..02a96987ed 100644
--- a/src/compiler/scala/reflect/reify/phases/Reify.scala
+++ b/src/compiler/scala/reflect/reify/phases/Reify.scala
@@ -9,6 +9,7 @@ trait Reify extends Symbols
                with Types
                with Names
                with Trees
+               with AnnotationInfos
                with Positions
                with Util {
 
@@ -30,6 +31,9 @@ trait Reify extends Symbols
     case tpe: Type                => reifyType(tpe)
     case name: Name               => reifyName(name)
     case tree: Tree               => reifyTree(tree)
+    // disabled because this is a very special case that I plan to remove later
+    // why do I dislike annotations? see comments to `reifyAnnotationInfo`
+//    case ann: AnnotationInfo      => reifyAnnotationInfo(ann)
     case pos: Position            => reifyPosition(pos)
     case mods: mirror.Modifiers   => reifyModifiers(mods)
     case xs: List[_]              => reifyList(xs)
diff --git a/src/compiler/scala/tools/nsc/util/Position.scala b/src/compiler/scala/tools/nsc/util/Position.scala
index 573f7bc7b2..208cd5703a 100644
--- a/src/compiler/scala/tools/nsc/util/Position.scala
+++ b/src/compiler/scala/tools/nsc/util/Position.scala
@@ -40,7 +40,15 @@ trait Position extends scala.reflect.api.Position with scala.reflect.api.Attachm
 
   /** A bit weird method that is necessary to safely update positions without destroying custom attachments */
   // necessary for conformance with Attachment
-  def withPos(pos: scala.reflect.api.Position) = pos
+  def withPos(newPos: scala.reflect.api.Position): scala.reflect.api.Attachment = newPos
+
+  /** Exposes itself as payload of Attachment */
+  // necessary for conformance with Attachment
+  def payload: Position = this
+
+  /** A bit weird method that is necessary to safely update positions without destroying custom attachments */
+  // necessary for conformance with Attachment
+  def withPayload(newPos: Any): scala.reflect.api.Attachment = newPos.asInstanceOf[Position]
 
   /** Java file corresponding to the source file of this position.
    */
diff --git a/src/library/scala/reflect/api/Attachment.scala b/src/library/scala/reflect/api/Attachment.scala
index dfd362ebe0..9fa5ceb0fb 100644
--- a/src/library/scala/reflect/api/Attachment.scala
+++ b/src/library/scala/reflect/api/Attachment.scala
@@ -7,10 +7,18 @@ package api
  *  Attachments have to carry positions, because we don't want to introduce even a single additional field in Tree
  *  imposing an unnecessary memory tax because of something that will not be used in most cases.
  */
+// [Eugene] with the introduction of `attach` and `payload[T]` users don't need to create custom attachments anymore
+// however, we cannot move attachments to scala.reflect.internal, because they are used in Trees, which are implemented completely in scala.reflect.api
 trait Attachment {
   /** Gets the underlying position */
   def pos: Position
 
   /** Creates a copy of this attachment with its position updated */
-  def withPos(pos: Position): Attachment
+  def withPos(newPos: Position): Attachment
+
+  /** Gets the underlying payload */
+  def payload: Any
+
+  /** Creates a copy of this attachment with its payload updated */
+  def withPayload(newPayload: Any): Attachment
 }
diff --git a/src/library/scala/reflect/api/StandardNames.scala b/src/library/scala/reflect/api/StandardNames.scala
index d2110ede75..d39d44dd86 100644
--- a/src/library/scala/reflect/api/StandardNames.scala
+++ b/src/library/scala/reflect/api/StandardNames.scala
@@ -44,6 +44,7 @@ trait StandardNames { self: Universe =>
     val MIRROR_FREE_PREFIX: TermName
     val MIRROR_FREE_THIS_SUFFIX: TermName
     val MIRROR_FREE_VALUE_SUFFIX: TermName
+    val MIRROR_SYMDEF_PREFIX: TermName
     val MIXIN_CONSTRUCTOR: TermName
     val MODULE_INSTANCE_FIELD: TermName
     val OUTER: TermName
diff --git a/src/library/scala/reflect/api/Symbols.scala b/src/library/scala/reflect/api/Symbols.scala
index a154e5f7a0..e47bc7216e 100755
--- a/src/library/scala/reflect/api/Symbols.scala
+++ b/src/library/scala/reflect/api/Symbols.scala
@@ -173,6 +173,11 @@ trait Symbols { self: Universe =>
      */
     def isSkolem       : Boolean
 
+    /** Does this symbol represent an existentially bound type?
+     *  If yes, `isType` is also guaranteed to be true.
+     */
+    def isExistential  : Boolean
+
     /** Does this symbol represent a free type captured by reification?
      */
     // needed for ones who wish to inspect reified trees
diff --git a/src/library/scala/reflect/api/Trees.scala b/src/library/scala/reflect/api/Trees.scala
index 6ddb2ea673..5ef73cba0c 100644
--- a/src/library/scala/reflect/api/Trees.scala
+++ b/src/library/scala/reflect/api/Trees.scala
@@ -85,10 +85,18 @@ trait Trees { self: Universe =>
     def pos_=(pos: Position): Unit = rawatt = (rawatt withPos pos) // the "withPos" part is crucial to robustness
     def setPos(newpos: Position): this.type = { pos = newpos; this }
 
-    private[this] var rawatt: Attachment = NoPosition
-    def attachment: Attachment = rawatt
-    def attachment_=(att: Attachment): Unit = rawatt = att
-    def setAttachment(att: Attachment): this.type = { rawatt = att; this }
+    private var rawatt: Attachment = NoPosition
+    private case class NontrivialAttachment(pos: api.Position, payload: Any) extends Attachment {
+      def withPos(newPos: api.Position) = copy(pos = newPos, payload = payload)
+      def withPayload(newPayload: Any) = copy(pos = pos, payload = newPayload)
+    }
+    // todo. annotate T with ClassTag and make pattern matcher use it
+    // todo. support multiple attachments, and remove the assignment. only leave attach/detach
+//    def attachment[T]: T = rawatt.payload.asInstanceOf[T]
+//    def attachmentOpt[T]: Option[T] = try { Some(rawatt.payload.asInstanceOf[T]) } catch { case _: Throwable => None }
+    def attachment: Any = rawatt.payload
+    def attachment_=(att: Any): Unit = rawatt = NontrivialAttachment(pos, att)
+    def setAttachment(att: Any): this.type = { attachment = att; this }
 
     private[this] var rawtpe: Type = _
 
@@ -238,7 +246,7 @@ trait Trees { self: Universe =>
       duplicateTree(this).asInstanceOf[this.type]
 
     private[scala] def copyAttrs(tree: Tree): this.type = {
-      attachment = tree.attachment
+      rawatt = tree.rawatt
       tpe = tree.tpe
       if (hasSymbol) symbol = tree.symbol
       this
diff --git a/src/library/scala/reflect/api/TypeTags.scala b/src/library/scala/reflect/api/TypeTags.scala
index 4ffabe1c36..59a7c87f44 100644
--- a/src/library/scala/reflect/api/TypeTags.scala
+++ b/src/library/scala/reflect/api/TypeTags.scala
@@ -61,9 +61,8 @@ trait TypeTags { self: Universe =>
     // assert(tpe != null)
 
     def sym = tpe.typeSymbol
-
-    def isConcrete = !isNotConcrete
-    def isNotConcrete = tpe exists (_.typeSymbol.isAbstractType)
+    def isConcrete = tpe.isConcrete
+    def notConcrete = !isConcrete
     def toConcrete: ConcreteTypeTag[T] = ConcreteTypeTag[T](tpe)
 
     override def toString = {
@@ -124,7 +123,7 @@ trait TypeTags { self: Universe =>
     // it's unsafe to use assert here, because we might run into deadlocks with Predef
     // also see comments in ClassTags.scala
     //assert(isConcrete, tpe)
-    if (isNotConcrete) throw new Error("%s (%s) is not concrete and cannot be used to construct a concrete type tag".format(tpe, tpe.kind))
+    if (notConcrete) throw new Error("%s (%s) is not concrete and cannot be used to construct a concrete type tag".format(tpe, tpe.kind))
     override def productPrefix = "ConcreteTypeTag"
   }
 
diff --git a/src/library/scala/reflect/api/Types.scala b/src/library/scala/reflect/api/Types.scala
index 12aad453b1..5e1c1af2fe 100755
--- a/src/library/scala/reflect/api/Types.scala
+++ b/src/library/scala/reflect/api/Types.scala
@@ -57,6 +57,10 @@ trait Types { self: Universe =>
      */
     def isHigherKinded: Boolean   // !!! This should be called "isTypeConstructor", no?
 
+    /** Does this type refer to abstract types or is an abstract type?
+     */
+    def isConcrete: Boolean
+
     /**
      *  Expands type aliases and converts higher-kinded TypeRefs to PolyTypes.
      *  Functions on types are also implemented as PolyTypes.
-- 
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