New phase ElimStaticThis

Author: odersky

src/dotty/tools/dotc/Compiler.scala

@@ -67,6 +67,7 @@ class Compiler {
            new Constructors,
            new FunctionalInterfaces),
       List(new LambdaLift,   // in this mini-phase block scopes are incorrect. No phases that rely on scopes should be here
+           new ElimStaticThis,
            new Flatten,
            new RestoreScopes),
       List(/*new PrivateToStatic,*/

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

@@ -0,0 +1,24 @@
+package dotty.tools.dotc
+package transform
+
+import core._
+import Contexts.Context
+import Flags._
+import dotty.tools.dotc.core.StdNames._
+import dotty.tools.dotc.core.SymDenotations.SymDenotation
+import TreeTransforms.{MiniPhaseTransform, TransformerInfo}
+
+/** Replace This references to module classes  in static methods by global identifiers to the
+ *  corresponding modules.
+ */
+class ElimStaticThis extends MiniPhaseTransform {
+  import ast.tpd._
+  def phaseName: String = "elimStaticThis"
+
+  override def transformThis(tree: This)(implicit ctx: Context, info: TransformerInfo): Tree =
+    if (!tree.symbol.is(Package) && ctx.owner.enclosingMethod.is(JavaStatic)) {
+      assert(tree.symbol.is(ModuleClass))
+      ref(tree.symbol.sourceModule)
+    }
+    else tree
+}