Copy types object when using a cached compiler.

dart/tests/compiler/dart2js/memory_compiler.dart

 // Copyright (c) 2013, 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.
 
 library dart2js.test.memory_compiler;
 
 import 'memory_source_file_helper.dart';
 
 import '../../../sdk/lib/_internal/compiler/implementation/dart2jslib.dart'
        show NullSink;
@@ skipping 147 matching lines @@
 
   Compiler compiler = new Compiler(readStringFromUri,
                                    outputProvider,
                                    handler,
                                    libraryRoot,
                                    packageRoot,
                                    options,
                                    {});
   if (cachedCompiler != null) {
     compiler.coreLibrary = cachedCompiler.libraries['dart:core'];
-    compiler.types = cachedCompiler.types;
+    compiler.types = cachedCompiler.types.copy(compiler);
     cachedCompiler.libraries.forEach((String uri, library) {
       if (library.isPlatformLibrary) {
         compiler.libraries[uri] = library;
         compiler.onLibraryLoaded(library, library.canonicalUri);
       }
     });
 
     compiler.symbolConstructor = cachedCompiler.symbolConstructor;
     compiler.mirrorSystemClass = cachedCompiler.mirrorSystemClass;
     compiler.mirrorsUsedClass = cachedCompiler.mirrorsUsedClass;
     compiler.mirrorSystemGetNameFunction =
         cachedCompiler.mirrorSystemGetNameFunction;
     compiler.symbolImplementationClass =
         cachedCompiler.symbolImplementationClass;
     compiler.symbolValidatedConstructor =
         cachedCompiler.symbolValidatedConstructor;
     compiler.mirrorsUsedConstructor = cachedCompiler.mirrorsUsedConstructor;
     compiler.deferredLibraryClass = cachedCompiler.deferredLibraryClass;
 
     Map cachedTreeElements =
         cachedCompiler.enqueuer.resolution.resolvedElements;
     cachedTreeElements.forEach((element, treeElements) {
       if (element.getLibrary().isPlatformLibrary) {
         compiler.enqueuer.resolution.resolvedElements[element] =
             treeElements;
       }
     });
+
+    // One potential problem that can occur when reusing elements is that there
+    // is a stale reference to an old compiler object.  By nulling out the old
+    // compiler's fields, such stale references are easier to identify.
+    cachedCompiler.scanner = null;
+    cachedCompiler.dietParser = null;
+    cachedCompiler.parser = null;
+    cachedCompiler.patchParser = null;
+    cachedCompiler.libraryLoader = null;
+    cachedCompiler.validator = null;
+    cachedCompiler.resolver = null;
+    cachedCompiler.closureToClassMapper = null;
+    cachedCompiler.checker = null;
+    cachedCompiler.irBuilder = null;
+    cachedCompiler.typesTask = null;
+    cachedCompiler.backend = null;
+    cachedCompiler.enqueuer = null;
+    cachedCompiler.deferredLoadTask = null;
+    cachedCompiler.mirrorUsageAnalyzerTask = null;
+    cachedCompiler.dumpInfoTask = null;
+    cachedCompiler.buildId = null;
   }
   return compiler;
 }
 
 Future<MirrorSystem> mirrorSystemFor(Map<String,String> memorySourceFiles,
                                      {DiagnosticHandler diagnosticHandler,
                                       List<String> options: const [],
                                       bool showDiagnostics: true}) {
   Uri libraryRoot = Uri.base.resolve('sdk/');
   Uri packageRoot = Uri.base.resolve('${Platform.packageRoot}/');
   Uri script = Uri.base.resolveUri(Platform.script);
 
   var provider = new MemorySourceFileProvider(memorySourceFiles);
   var handler =
       createDiagnosticHandler(diagnosticHandler, provider, showDiagnostics);
 
   List<Uri> libraries = <Uri>[];
   memorySourceFiles.forEach((String path, _) {
     libraries.add(new Uri(scheme: 'memory', path: path));
   });
 
   return analyze(libraries, libraryRoot, packageRoot,
                  provider, handler, options);
 }