1 files changed, 90 insertions, 0 deletions
diff --git a/src/dotty/tools/dotc/transform/PrivateToStatic.scala b/src/dotty/tools/dotc/transform/PrivateToStatic.scala
new file mode 100644
index 000000000..17f176855
--- /dev/null
+++ b/src/dotty/tools/dotc/transform/PrivateToStatic.scala
@@ -0,0 +1,90 @@
+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
+
+/** 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 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)).asInstanceOf[SymDenotation]
+      .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
+
+    override def transformApply(tree: Apply)(implicit ctx: Context, info: TransformerInfo) =
+      tree.fun match {
+        case fun @ Select(qual, name) if shouldBeStatic(fun.symbol) =>
+          println(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
+    }
+  }
+}