Transform/private to static

src/dotty/tools/dotc/Compiler.scala

@@ -55,7 +55,10 @@ class Compiler {
       List(new Erasure),
       List(new CapturedVars,
            new Constructors),
-      List(new LambdaLift)
+      List(new LambdaLift,
+           new Flatten,
+           new RestoreScopes),
+      List(new PrivateToStatic)
     )
 
   var runId = 1

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

@@ -347,6 +347,11 @@ object Trees {
       s
     }
 
+    /** If this is a thicket, gerform `op` on each of its trees
+     *  otherwise, perform `op` ion tree itself.
+     */
+    def foreachInThicket(op: Tree[T] => Unit): Unit = op(this)
+
     override def toText(printer: Printer) = printer.toText(this)
 
     override def hashCode(): Int = System.identityHashCode(this)
@@ -809,6 +814,8 @@ object Trees {
       val newTrees = trees.map(_.withPos(pos))
       new Thicket[T](newTrees).asInstanceOf[this.type]
     }
+    override def foreachInThicket(op: Tree[T] => Unit): Unit =
+      trees foreach (_.foreachInThicket(op))
   }
 
   class EmptyValDef[T >: Untyped] extends ValDef[T](

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

@@ -263,7 +263,7 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
       case _ =>
         false
     }
-    try test
+    try test || tp.symbol.is(JavaStatic)
     catch { // See remark in SymDenotations#accessWithin
       case ex: NotDefinedHere => test(ctx.addMode(Mode.FutureDefsOK))
     }

src/dotty/tools/dotc/core/Flags.scala

@@ -512,6 +512,9 @@ object Flags {
   /** Labeled `private` or `final` */
   final val PrivateOrFinal = Private | Final
 
+  /** A private method */
+  final val PrivateMethod = allOf(Private, Method)
+
   /** A type parameter with synthesized name */
   final val ExpandedTypeParam = allOf(ExpandedName, TypeParam)
 

src/dotty/tools/dotc/printing/RefinedPrinter.scala

@@ -36,7 +36,7 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
   override def nameString(name: Name): String = name.decode.toString
 
   override protected def simpleNameString(sym: Symbol): String =
-    sym.originalName.decode.toString
+    sym.name.decode.toString
 
   override protected def fullNameOwner(sym: Symbol) = {
     val owner = super.fullNameOwner(sym)
@@ -222,7 +222,9 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
         "`" ~ toText(id.name) ~ "`"
       case Ident(name) =>
         tree.typeOpt match {
-          case tp: NamedType if name != nme.WILDCARD => toTextPrefix(tp.prefix) ~ selectionString(tp)
+          case tp: NamedType if name != nme.WILDCARD =>
+            val pre = if (tp.symbol is JavaStatic) tp.prefix.widen else tp.prefix
+            toTextPrefix(pre) ~ selectionString(tp)
           case _ => toText(name)
         }
       case tree @ Select(qual, name) =>

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

@@ -0,0 +1,49 @@
+package dotty.tools.dotc
+package transform
+
+import core._
+import DenotTransformers.SymTransformer
+import Phases.Phase
+import Contexts.Context
+import Flags._
+import SymUtils._
+import SymDenotations.SymDenotation
+import collection.mutable
+import TreeTransforms.MiniPhaseTransform
+import dotty.tools.dotc.transform.TreeTransforms.TransformerInfo
+
+class Flatten extends MiniPhaseTransform with SymTransformer { thisTransform =>
+  import ast.tpd._
+  override def phaseName = "flatten"
+
+  def transformSym(ref: SymDenotation)(implicit ctx: Context) = {
+    if (ref.isClass && !ref.is(Package) && !ref.owner.is(Package)) {
+      ref.copySymDenotation(
+        name = ref.flatName,
+        owner = ref.enclosingPackageClass)
+    }
+    else ref
+  }
+
+  override def treeTransformPhase = thisTransform.next
+
+  private val liftedDefs = new mutable.ListBuffer[Tree]
+
+  private def liftIfNested(tree: Tree)(implicit ctx: Context, info: TransformerInfo) =
+    if (ctx.owner is Package) tree
+    else {
+      transformFollowing(tree).foreachInThicket(liftedDefs += _)
+      EmptyTree
+    }
+
+  override def transformStats(stats: List[Tree])(implicit ctx: Context, info: TransformerInfo) =
+    if (ctx.owner is Package) {
+      val liftedStats = stats ++ liftedDefs
+      liftedDefs.clear
+      liftedStats
+    }
+    else stats
+
+  override def transformTypeDef(tree: TypeDef)(implicit ctx: Context, info: TransformerInfo) =
+    liftIfNested(tree)
+}

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

@@ -278,20 +278,20 @@ class LambdaLift extends MiniPhaseTransform with IdentityDenotTransformer { this
     }
   }
 
-  override def init(implicit ctx: Context, info: TransformerInfo) = {
-    free.clear()
-    proxyMap.clear()
-    called.clear()
-    calledFromInner.clear()
-    liftedOwner.clear()
-    liftedDefs.clear()
-    assert(ctx.phase == thisTransform)
-    (new CollectDependencies).traverse(NoSymbol, ctx.compilationUnit.tpdTree)
-    computeFreeVars()
-    computeLiftedOwners()
-    generateProxies()(ctx.withPhase(thisTransform.next))
-    liftLocals()(ctx.withPhase(thisTransform.next))
-  }
+  override def init(implicit ctx: Context, info: TransformerInfo) =
+    ctx.atPhase(thisTransform) { implicit ctx =>
+      free.clear()
+      proxyMap.clear()
+      called.clear()
+      calledFromInner.clear()
+      liftedOwner.clear()
+      liftedDefs.clear()
+      (new CollectDependencies).traverse(NoSymbol, ctx.compilationUnit.tpdTree)
+      computeFreeVars()
+      computeLiftedOwners()
+      generateProxies()(ctx.withPhase(thisTransform.next))
+      liftLocals()(ctx.withPhase(thisTransform.next))
+    }
 
   private def currentEnclosure(implicit ctx: Context) =
     ctx.owner.enclosingMethod.skipConstructor
@@ -355,8 +355,9 @@ class LambdaLift extends MiniPhaseTransform with IdentityDenotTransformer { this
       }
   }
 
-  private def liftDef(tree: MemberDef)(implicit ctx: Context): Tree = {
-    liftedDefs(tree.symbol.owner) += rename(tree, tree.symbol.name)
+  private def liftDef(tree: MemberDef)(implicit ctx: Context, info: TransformerInfo): Tree = {
+    val buf = liftedDefs(tree.symbol.owner)
+    transformFollowing(rename(tree, tree.symbol.name)).foreachInThicket(buf += _)
     EmptyTree
   }
 

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

@@ -0,0 +1,97 @@
+package dotty.tools.dotc
+package transform
+
+import core._
+import DenotTransformers.SymTransformer
+import Contexts.Context
+import Symbols._
+import Scopes._
+import Flags._
+import StdNames._
+import SymDenotations._
+import Types._
+import collection.mutable
+import TreeTransforms._
+import Decorators._
+import ast.Trees._
+import TreeTransforms.TransformerInfo
+
+/** Makes private methods static, provided they not deferred, accessors, or static,
+ *  by rewriting a method `m` in class `C` as follows:
+ *
+ *     private def m(ps) = e
+ *
+ *     --> private static def($this: C, ps) = [this -> $this] e
+ */
+class PrivateToStatic extends MiniPhase with SymTransformer { thisTransform =>
+  import ast.tpd._
+  override def phaseName = "privateToStatic"
+  override def relaxedTyping = true
+
+  private val Immovable = Deferred | Accessor | JavaStatic
+
+  def shouldBeStatic(sd: SymDenotation)(implicit ctx: Context) =
+    sd.current(ctx.withPhase(thisTransform)).asSymDenotation
+      .is(PrivateMethod, butNot = Immovable) &&
+    (sd.owner.is(Trait) || sd.is(NotJavaPrivate))
+
+  override def transformSym(sd: SymDenotation)(implicit ctx: Context): SymDenotation =
+    if (shouldBeStatic(sd)) {
+      val mt @ MethodType(pnames, ptypes) = sd.info
+      sd.copySymDenotation(
+        initFlags = sd.flags | JavaStatic,
+        info = MethodType(nme.SELF :: pnames, sd.owner.thisType :: ptypes, mt.resultType))
+    }
+    else sd
+
+  val treeTransform = new Transform(NoSymbol)
+
+  class Transform(thisParam: Symbol) extends TreeTransform {
+    def phase = thisTransform
+    override def treeTransformPhase = thisTransform.next
+
+    override def prepareForDefDef(tree: DefDef)(implicit ctx: Context) =
+      if (shouldBeStatic(tree.symbol)) {
+        val selfParam = ctx.newSymbol(tree.symbol, nme.SELF, Param, tree.symbol.owner.thisType, coord = tree.pos)
+        new Transform(selfParam)
+      }
+      else this
+
+    override def transformDefDef(tree: DefDef)(implicit ctx: Context, info: TransformerInfo) =
+      if (shouldBeStatic(tree.symbol)) {
+        val thisParamDef = ValDef(thisParam.asTerm)
+        val vparams :: Nil = tree.vparamss
+        cpy.DefDef(tree)(
+          mods = tree.mods | JavaStatic,
+          vparamss = (thisParamDef :: vparams) :: Nil)
+      }
+      else tree
+
+    override def transformThis(tree: This)(implicit ctx: Context, info: TransformerInfo) =
+      if (shouldBeStatic(ctx.owner.enclosingMethod)) ref(thisParam).withPos(tree.pos)
+      else tree
+
+    /** Rwrites a call to a method `m` which is made static as folows:
+     *
+     *    qual.m(args)  -->  m(qual, args)
+     */
+    override def transformApply(tree: Apply)(implicit ctx: Context, info: TransformerInfo) =
+      tree.fun match {
+        case fun @ Select(qual, name) if shouldBeStatic(fun.symbol) =>
+          ctx.debuglog(i"mapping $tree to ${cpy.Ident(fun)(name)} (${qual :: tree.args}%, %)")
+          cpy.Apply(tree)(ref(fun.symbol).withPos(fun.pos), qual :: tree.args)
+        case _ =>
+          tree
+      }
+
+    override def transformClosure(tree: Closure)(implicit ctx: Context, info: TransformerInfo) =
+      tree.meth match {
+        case meth @ Select(qual, name) if shouldBeStatic(meth.symbol) =>
+          cpy.Closure(tree)(
+            env = qual :: tree.env,
+            meth = ref(meth.symbol).withPos(meth.pos))
+        case _ =>
+          tree
+    }
+  }
+}

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

@@ -0,0 +1,36 @@
+package dotty.tools.dotc
+package transform
+
+import core._
+import DenotTransformers.IdentityDenotTransformer
+import Contexts.Context
+import Symbols._
+import Scopes._
+import collection.mutable
+import TreeTransforms.MiniPhaseTransform
+import ast.Trees._
+import TreeTransforms.TransformerInfo
+
+/** The preceding lambda lift and flatten phases move symbols to different scopes
+ *  and rename them. This miniphase cleans up afterwards and makes sure that all
+ *  class scopes contain the symbols defined in them.
+ */
+class RestoreScopes extends MiniPhaseTransform with IdentityDenotTransformer { thisTransform =>
+  import ast.tpd._
+  override def phaseName = "restoreScopes"
+
+  override def treeTransformPhase = thisTransform.next
+
+  override def transformTypeDef(tree: TypeDef)(implicit ctx: Context, info: TransformerInfo) = {
+    val TypeDef(_, _, Template(constr, _, _, body)) = tree
+    val restoredDecls = newScope
+    for (stat <- constr :: body)
+      if (stat.isInstanceOf[MemberDef] && stat.symbol.exists)
+        restoredDecls.enter(stat.symbol)
+    val cinfo = tree.symbol.asClass.classInfo
+    tree.symbol.copySymDenotation(
+      info = cinfo.derivedClassInfo( // Dotty deviation: Cannot expand cinfo inline without a type error
+        decls = restoredDecls: Scope)).installAfter(thisTransform)
+    tree
+  }
+}

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

@@ -295,7 +295,7 @@ class SuperAccessors extends MacroTransform with IdentityDenotTransformer { this
             val body1 = forwardParamAccessors(transformStats(impl.body, tree.symbol))
             accDefs -= currentClass
             ownStats ++= body1
-            cpy.Template(impl)(body = body1)
+            cpy.Template(impl)(body = ownStats.toList)
           }
           transformTemplate
 

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

@@ -5,6 +5,7 @@ import core._
 import Types._
 import Contexts._
 import Symbols._
+import SymDenotations._
 import Decorators._
 import Names._
 import StdNames._
@@ -13,7 +14,8 @@ import Flags._
 import language.implicitConversions
 
 object SymUtils {
-  implicit def decorateSymUtils(sym: Symbol): SymUtils = new SymUtils(sym)
+  implicit def decorateSymbol(sym: Symbol): SymUtils = new SymUtils(sym)
+  implicit def decorateSymDenot(d: SymDenotation): SymUtils = new SymUtils(d.symbol)
 }
 
 /** A decorator that provides methods on symbols
@@ -64,4 +66,7 @@ class SymUtils(val self: Symbol) extends AnyVal {
 
   def field(implicit ctx: Context): Symbol =
     self.owner.info.decl(self.asTerm.name.fieldName).suchThat(!_.is(Method)).symbol
+
+  /** `fullName` where `$' is the separator character */
+  def flatName(implicit ctx: Context): Name = self.fullNameSeparated('$')
 }

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

@@ -180,7 +180,7 @@ class TreeChecker {
     override def typedStats(trees: List[untpd.Tree], exprOwner: Symbol)(implicit ctx: Context): List[Tree] = {
       for (tree <- trees) tree match {
         case tree: untpd.DefTree => checkOwner(tree)
-        case _: untpd.Thicket => assert(false, "unexpanded thicket in statement sequence")
+        case _: untpd.Thicket => assert(false, i"unexpanded thicket $tree in statement sequence $trees%\n%")
         case _ =>
       }
       super.typedStats(trees, exprOwner)

src/dotty/tools/dotc/typer/Applications.scala

@@ -461,7 +461,7 @@ trait Applications extends Compatibility { self: Typer =>
 
     val result = {
       var typedArgs = typedArgBuf.toList
-      val app0 = cpy.Apply(app)(normalizedFun, typedArgs)
+      def app0 = cpy.Apply(app)(normalizedFun, typedArgs) // needs to be a `def` because typedArgs can change later
       val app1 =
         if (!success) app0.withType(ErrorType)
         else {

test/dotc/tests.scala

@@ -15,7 +15,7 @@ class tests extends CompilerTest {
 
   implicit val defaultOptions = noCheckOptions ++ List(
       "-Yno-deep-subtypes",
-      "-Ycheck:patternMatcher,gettersSetters,lambdaLift"
+      "-Ycheck:patternMatcher,gettersSetters,restoreScopes"
   )
 
   val twice = List("#runs", "2", "-YnoDoubleBindings")