A visitor that builds a map from node to "Usage".

lib/compiler/implementation/dart_backend/backend.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 class BailoutException {
   final String reason;
 
   const BailoutException(this.reason);
 }
 
@@ skipping 52 matching lines @@
     final LIBS_TO_IGNORE = [
       compiler.jsHelperLibrary,
       compiler.interceptorsLibrary,
     ];
     bool shouldOutput(Element element) =>
       element.kind !== ElementKind.VOID &&
       LIBS_TO_IGNORE.indexOf(element.getLibrary()) == -1 &&
       !isDartCoreLib(compiler, element.getLibrary());
 
     try {
-      Emitter emitter = new Emitter(compiler);
+      PlaceholderCollector collector = new PlaceholderCollector(compiler);
+      resolvedElements.forEach((element, treeElements) {
+        if (!shouldOutput(element)) return;
+        collector.collect(element, treeElements);
+      });
+
+      ConflictingRenamer renamer =
+          new ConflictingRenamer(compiler, collector.placeholders);
+      Emitter emitter = new Emitter(compiler, renamer);
       resolvedElements.forEach((element, treeElements) {
         if (!shouldOutput(element)) return;
         if (element.isMember()) {
           var enclosingClass = element.enclosingElement;
           assert(enclosingClass.isClass());
           assert(enclosingClass.isTopLevel());
           addMemberToClass(element, enclosingClass);
           return;
         }
         if (!element.isTopLevel()) {
@@ skipping 24 matching lines @@
  */
 bool isDartCoreLib(Compiler compiler, LibraryElement libraryElement) {
   final libraries = compiler.libraries;
   for (final uri in libraries.getKeys()) {
     if (libraryElement === libraries[uri]) {
       if (uri.startsWith('dart:')) return true;
     }
   }
   return false;
 }