Drop Java compilation units after Typer

Java compilation units should not be retained after typer,
as no code will be generated for them. All we need from
them are their symbols.

Author: odersky

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

@@ -27,26 +27,24 @@ class Pickler extends Phase {
 
   override def run(implicit ctx: Context): Unit = {
     val unit = ctx.compilationUnit
-    if (!unit.isJava) {
-      val tree = unit.tpdTree
-      pickling.println(i"unpickling in run ${ctx.runId}")
-      if (ctx.settings.YtestPickler.value) beforePickling(unit) = tree.show
+    val tree = unit.tpdTree
+    pickling.println(i"unpickling in run ${ctx.runId}")
+    if (ctx.settings.YtestPickler.value) beforePickling(unit) = tree.show
 
-      val pickler = unit.pickler
-      val treePkl = new TreePickler(pickler)
-      treePkl.pickle(tree :: Nil)
-      unit.addrOfTree = treePkl.buf.addrOfTree
-      unit.addrOfSym = treePkl.addrOfSym
-      if (tree.pos.exists)
-        new PositionPickler(pickler, treePkl.buf.addrOfTree).picklePositions(tree :: Nil, tree.pos)
+    val pickler = unit.pickler
+    val treePkl = new TreePickler(pickler)
+    treePkl.pickle(tree :: Nil)
+    unit.addrOfTree = treePkl.buf.addrOfTree
+    unit.addrOfSym = treePkl.addrOfSym
+    if (tree.pos.exists)
+      new PositionPickler(pickler, treePkl.buf.addrOfTree).picklePositions(tree :: Nil, tree.pos)
 
-      def rawBytes = // not needed right now, but useful to print raw format.
-        unit.pickler.assembleParts().iterator.grouped(10).toList.zipWithIndex.map {
-          case (row, i) => s"${i}0: ${row.mkString(" ")}"
-        }
-      // println(i"rawBytes = \n$rawBytes%\n%") // DEBUG
-      if (pickling ne noPrinter) new TastyPrinter(pickler.assembleParts()).printContents()
-    }
+    def rawBytes = // not needed right now, but useful to print raw format.
+      unit.pickler.assembleParts().iterator.grouped(10).toList.zipWithIndex.map {
+        case (row, i) => s"${i}0: ${row.mkString(" ")}"
+      }
+    // println(i"rawBytes = \n$rawBytes%\n%") // DEBUG
+    if (pickling ne noPrinter) new TastyPrinter(pickler.assembleParts()).printContents()
   }
 
   override def runOn(units: List[CompilationUnit])(implicit ctx: Context): List[CompilationUnit] = {

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

@@ -51,7 +51,7 @@ class FrontEnd extends Phase {
     unitContexts foreach (enterSyms(_))
     unitContexts foreach (typeCheck(_))
     record("totalTrees", ast.Trees.ntrees)
-    unitContexts.map(_.compilationUnit)
+    unitContexts.map(_.compilationUnit).filter(!_.isJava)
   }
 
   override def run(implicit ctx: Context): Unit = {