More docs and removing print statements

Author: odersky

src/dotty/tools/dotc/Compiler.scala

@@ -46,7 +46,6 @@ class Compiler {
            new TailRec),
       List(new PatternMatcher,
            new ExplicitOuter,
-           // new LazyValTranformContext().transformer, // disabled, awaiting fixes
            new Splitter),
       List(new ElimByName,
            new InterceptedMethods,
@@ -55,7 +54,7 @@ class Compiler {
            new ResolveSuper),
       List(new Erasure),
       List(new Mixin,
-           new Memoize,
+           new Memoize, // TODO: Make LazyVals a part of this phase
            new CapturedVars,
            new Constructors),
       List(new LambdaLift,

src/dotty/tools/dotc/ast/tpd.scala

@@ -546,10 +546,8 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
         def traverse(tree: Tree) = tree match {
           case tree: DefTree =>
             val sym = tree.symbol
-            if (sym.denot(ctx.withPhase(trans)).owner == from) {
-              println(i"change owner $from -> $to of $sym")
+            if (sym.denot(ctx.withPhase(trans)).owner == from)
               sym.copySymDenotation(owner = to).installAfter(trans)
-            }
             if (sym.isWeakOwner) traverseChildren(tree)
           case _ =>
             traverseChildren(tree)

src/dotty/tools/dotc/transform/Getters.scala

@@ -36,6 +36,8 @@ import Decorators._
  *
  *     p.x = e
  *      -->  p.x_=(e)
+ *
+ *  No fields are generated yet. This is done later in phase Memoize.
  */
 class Getters extends MiniPhaseTransform with SymTransformer { thisTransform =>
   import ast.tpd._

src/dotty/tools/dotc/transform/Memoize.scala

@@ -37,6 +37,12 @@ import Decorators._
   override def phaseName = "memoize"
   override def treeTransformPhase = thisTransform.next
 
+  /** Should to run after mixin so that fields get generated in the
+   *  class that contains the concrete getter rather than the trait
+   *  that defines it.
+   */
+  override def runsAfter: Set[Class[_ <: Phase]] = Set(classOf[Mixin])
+
   override def prepareForDefDef(tree: DefDef)(implicit ctx: Context) = {
     val sym = tree.symbol
     if (sym.isGetter && !sym.is(NoFieldNeeded)) {

src/dotty/tools/dotc/transform/Mixin.scala

@@ -13,10 +13,10 @@ import Decorators._
 import DenotTransformers._
 import StdNames._
 import NameOps._
+import Phases._
 import ast.Trees._
 import collection.mutable
 
-// todo: interface
 /** This phase performs the following transformations:
  *
  *  1. (done in `traitDefs`) Map every concrete trait getter
@@ -57,14 +57,20 @@ import collection.mutable
  *          3.3 (done in `setters`) For every concrete setter `<mods> def x_=(y: T)` in M:
  *
  *                <mods> def x_=(y: T) = ()
+ *
+ *  Conceptually, this is the second half of the previous mixin phase. It needs to run
+ *  after erasure because it copies references to possibly private inner classes and objects
+ *  into enclosing classes where they are not visible. This can only be done if all references
+ *  are symbolic.
  */
 class Mixin extends MiniPhaseTransform with SymTransformer { thisTransform =>
   import ast.tpd._
 
   override def phaseName: String = "mixin"
-
   override def treeTransformPhase = thisTransform.next
 
+  override def runsAfter: Set[Class[_ <: Phase]] = Set(classOf[Erasure])
+
   override def transformSym(sym: SymDenotation)(implicit ctx: Context): SymDenotation =
     if (sym.is(Accessor, butNot = Deferred) && sym.owner.is(Trait))
       sym.copySymDenotation(initFlags = sym.flags | Deferred)

src/dotty/tools/dotc/transform/ResolveSuper.scala

@@ -39,6 +39,9 @@ import collection.mutable
  *
  *        A method in M needs to be disambiguated if it is concrete, not overridden in C,
  *        and if it overrides another concrete method.
+ *
+ *  This is the first part of what was the mixin phase. It is complemented by
+ *  Mixin, which runs after erasure.
  */
 class ResolveSuper extends MiniPhaseTransform with IdentityDenotTransformer { thisTransform =>
   import ast.tpd._
@@ -61,11 +64,11 @@ class ResolveSuper extends MiniPhaseTransform with IdentityDenotTransformer { th
       var bcs = cls.info.baseClasses.dropWhile(acc.owner != _).tail
       var sym: Symbol = NoSymbol
       val SuperAccessorName(memberName) = acc.name: Name // dotty deviation: ": Name" needed otherwise pattern type is neither a subtype nor a supertype of selector type
-      println(i"starting rebindsuper from $cls of ${acc.showLocated}: ${acc.info} in $bcs, name = $memberName")
+      ctx.debuglog(i"starting rebindsuper from $cls of ${acc.showLocated}: ${acc.info} in $bcs, name = $memberName")
       while (bcs.nonEmpty && sym == NoSymbol) {
         val other = bcs.head.info.nonPrivateDecl(memberName)
-        //if (ctx.settings.debug.value)
-          println(i"rebindsuper ${bcs.head} $other deferred = ${other.symbol.is(Deferred)}")
+        if (ctx.settings.debug.value)
+          ctx.log(i"rebindsuper ${bcs.head} $other deferred = ${other.symbol.is(Deferred)}")
         sym = other.matchingDenotation(cls.thisType, cls.thisType.memberInfo(acc)).symbol
         bcs = bcs.tail
       }