Recreate FreshNameCreator for each run.

Previously only the FrontEnd got a fresh FreshNameCreator for
each run, the other phases used a global one instead. This means
that compiling the same file several times would create different
synthetic names and classes on each run.

Author: odersky

src/dotty/tools/dotc/Compiler.scala

@@ -11,6 +11,7 @@ import typer.{FrontEnd, Typer, ImportInfo, RefChecks}
 import reporting.{Reporter, ConsoleReporter}
 import Phases.Phase
 import transform._
+import util.FreshNameCreator
 import transform.TreeTransforms.{TreeTransform, TreeTransformer}
 import core.DenotTransformers.DenotTransformer
 import core.Denotations.SingleDenotation
@@ -140,7 +141,8 @@ class Compiler {
       .setTyper(new Typer)
       .setMode(Mode.ImplicitsEnabled)
       .setTyperState(new MutableTyperState(ctx.typerState, ctx.typerState.reporter, isCommittable = true))
-    ctx.initialize()(start) // re-initialize the base context with start
+      .setFreshNames(new FreshNameCreator.Default)
+  ctx.initialize()(start) // re-initialize the base context with start
     def addImport(ctx: Context, refFn: () => TermRef) =
       ctx.fresh.setImportInfo(ImportInfo.rootImport(refFn)(ctx))
     (start.setRunInfo(new RunInfo(start)) /: defn.RootImportFns)(addImport)

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

@@ -12,7 +12,6 @@ import config.Printers.{typr, default}
 import util.Stats._
 import scala.util.control.NonFatal
 import ast.Trees._
-import util.FreshNameCreator
 
 class FrontEnd extends Phase {
 
@@ -66,7 +65,7 @@ class FrontEnd extends Phase {
   override def runOn(units: List[CompilationUnit])(implicit ctx: Context): List[CompilationUnit] = {
     val unitContexts = for (unit <- units) yield {
       ctx.inform(s"compiling ${unit.source}")
-      ctx.fresh.setCompilationUnit(unit).setFreshNames(new FreshNameCreator.Default)
+      ctx.fresh.setCompilationUnit(unit)
     }
     unitContexts foreach (parse(_))
     record("parsedTrees", ast.Trees.ntrees)