Parallel build-mode and DDC changes for summary2.

It does not enable summary2 yet, but makes it possible to flip
one flag AnalysisDriver.useSummary2 to switch between summary1
and summary2.

I run presubmit scripts, and it seems that it works for both.
https://test.corp.google.com/ui#id=OCL:255717824:BASE:259228828:1563746330268:5481d33a
https://test.corp.google.com/ui#id=OCL:255717824:BASE:258892260:1563515248201:2d5ce329

One thing that is not implemented yet is tracking used dependencies
for summary2. So, //dart/bazel_codegen_tests:dependencies_test_run fails.


Change-Id: Iec9f3852e9b91236ce98e87041031daa0cc71a88
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/107689
Reviewed-by: Paul Berry <paulberry@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Vijay Menon <vsm@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

pkg/analyzer/lib/src/dart/analysis/ddc.dart

@@ -20,6 +20,8 @@ import 'package:analyzer/src/summary/package_bundle_reader.dart';
 import 'package:analyzer/src/summary/resynthesize.dart';
 import 'package:analyzer/src/summary/summarize_ast.dart';
 import 'package:analyzer/src/summary/summarize_elements.dart';
+import 'package:analyzer/src/summary/summary_sdk.dart';
+import 'package:analyzer/src/summary2/informative_data.dart';
 import 'package:analyzer/src/summary2/link.dart' as summary2;
 import 'package:analyzer/src/summary2/linked_bundle_context.dart' as summary2;
 import 'package:analyzer/src/summary2/linked_element_factory.dart' as summary2;
@@ -36,6 +38,8 @@ class DevCompilerResynthesizerBuilder {
 
   _SourceCrawler _fileCrawler;
 
+  final List<_UnitInformativeData> _informativeData = [];
+
   final PackageBundleAssembler _assembler;
   List<int> summaryBytes;
 
@@ -83,17 +87,21 @@ class DevCompilerResynthesizerBuilder {
     );
     context = RestrictedAnalysisContext(synchronousSession, _sourceFactory);
 
-    resynthesizer = StoreBasedSummaryResynthesizer(
-      context,
-      null,
-      context.sourceFactory,
-      /*strongMode*/ true,
-      SummaryDataStore([])
-        ..addStore(_summaryData)
-        ..addBundle(null, bundle),
-    );
-    resynthesizer.finishCoreAsyncLibraries();
-    context.typeProvider = resynthesizer.typeProvider;
+    if (AnalysisDriver.useSummary2) {
+      _createElementFactory(bundle);
+    } else {
+      resynthesizer = StoreBasedSummaryResynthesizer(
+        context,
+        null,
+        context.sourceFactory,
+        /*strongMode*/ true,
+        SummaryDataStore([])
+          ..addStore(_summaryData)
+          ..addBundle(null, bundle),
+      );
+      resynthesizer.finishCoreAsyncLibraries();
+      context.typeProvider = resynthesizer.typeProvider;
+    }
   }
 
   void _buildPackageBundleBytes() {
@@ -126,31 +134,62 @@ class DevCompilerResynthesizerBuilder {
     var inputLibraries = <summary2.LinkInputLibrary>[];
 
     var sourceToUnit = _fileCrawler.sourceToUnit;
-    for (var librarySource in sourceToUnit.keys) {
+    for (var librarySource in _fileCrawler.librarySources) {
+      var libraryUriStr = '${librarySource.uri}';
       var unit = sourceToUnit[librarySource];
 
-      if (_explicitSources.contains(librarySource.uri)) {
-        var isPart = unit.directives.any((d) => d is PartOfDirective);
-        if (isPart) {
-          continue;
-        }
-      }
-
       var inputUnits = <summary2.LinkInputUnit>[];
       inputUnits.add(
         summary2.LinkInputUnit(null, librarySource, false, unit),
       );
 
+      _informativeData.add(
+        _UnitInformativeData(
+          libraryUriStr,
+          libraryUriStr,
+          createInformativeData(unit),
+        ),
+      );
+
       for (var directive in unit.directives) {
         if (directive is PartDirective) {
-          var partUri = directive.uri.stringValue;
-          var partSource = _sourceFactory.resolveUri(librarySource, partUri);
-          if (partSource != null) {
-            var partUnit = sourceToUnit[partSource];
+          var partRelativeUriStr = directive.uri.stringValue;
+          var partSource = _sourceFactory.resolveUri(
+            librarySource,
+            partRelativeUriStr,
+          );
+
+          // Add empty synthetic units for unresolved `part` URIs.
+          if (partSource == null) {
             inputUnits.add(
-              summary2.LinkInputUnit(partUri, partSource, false, partUnit),
+              summary2.LinkInputUnit(
+                partRelativeUriStr,
+                null,
+                true,
+                _fsState.unresolvedFile.parse(),
+              ),
             );
+            continue;
           }
+
+          var partUnit = sourceToUnit[partSource];
+          inputUnits.add(
+            summary2.LinkInputUnit(
+              partRelativeUriStr,
+              partSource,
+              partSource == null,
+              partUnit,
+            ),
+          );
+
+          var unitUriStr = '${partSource.uri}';
+          _informativeData.add(
+            _UnitInformativeData(
+              libraryUriStr,
+              unitUriStr,
+              createInformativeData(partUnit),
+            ),
+          );
         }
       }
 
@@ -179,6 +218,40 @@ class DevCompilerResynthesizerBuilder {
     var linkResult = summary2.link(elementFactory, inputLibraries);
     _assembler.setBundle2(linkResult.bundle);
   }
+
+  void _createElementFactory(PackageBundle newBundle) {
+    elementFactory = summary2.LinkedElementFactory(
+      context,
+      null,
+      summary2.Reference.root(),
+    );
+    for (var bundle in _summaryData.bundles) {
+      elementFactory.addBundle(
+        summary2.LinkedBundleContext(elementFactory, bundle.bundle2),
+      );
+    }
+    elementFactory.addBundle(
+      summary2.LinkedBundleContext(elementFactory, newBundle.bundle2),
+    );
+
+    for (var unitData in _informativeData) {
+      elementFactory.setInformativeData(
+        unitData.libraryUriStr,
+        unitData.unitUriStr,
+        unitData.data,
+      );
+    }
+
+    var dartCore = elementFactory.libraryOfUri('dart:core');
+    var dartAsync = elementFactory.libraryOfUri('dart:async');
+    var typeProvider = SummaryTypeProvider()
+      ..initializeCore(dartCore)
+      ..initializeAsync(dartAsync);
+    context.typeProvider = typeProvider;
+
+    dartCore.createLoadLibraryFunction(typeProvider);
+    dartAsync.createLoadLibraryFunction(typeProvider);
+  }
 }
 
 class _SourceCrawler {
@@ -198,6 +271,7 @@ class _SourceCrawler {
   final Map<String, UnlinkedUnitBuilder> uriToUnlinkedUnit = {};
   final Map<Source, CompilationUnit> sourceToUnit = {};
   final List<String> libraryUris = [];
+  final List<Source> librarySources = [];
 
   _SourceCrawler(
     this._fsState,
@@ -230,7 +304,7 @@ class _SourceCrawler {
     var uriStr = uri.toString();
 
     // Maybe an input package contains the source.
-    if (_summaryData.unlinkedMap[uriStr] != null) {
+    if (_summaryData.hasUnlinkedUnit(uriStr)) {
       return;
     }
 
@@ -273,6 +347,15 @@ class _SourceCrawler {
     // Remember library URIs, for linking and compiling.
     if (!isPart) {
       libraryUris.add(uriStr);
+      librarySources.add(source);
     }
   }
 }
+
+class _UnitInformativeData {
+  final String libraryUriStr;
+  final String unitUriStr;
+  final List<UnlinkedInformativeData> data;
+
+  _UnitInformativeData(this.libraryUriStr, this.unitUriStr, this.data);
+}

pkg/analyzer/lib/src/dart/analysis/file_state.dart

@@ -244,7 +244,7 @@ class FileState {
    */
   bool get isExternalLibrary {
     return _fsState.externalSummaries != null &&
-        _fsState.externalSummaries.linkedMap.containsKey(uriStr);
+        _fsState.externalSummaries.hasLinkedLibrary(uriStr);
   }
 
   /**
@@ -253,8 +253,8 @@ class FileState {
    */
   bool get isPart {
     if (_fsState.externalSummaries != null &&
-        _fsState.externalSummaries.unlinkedMap.containsKey(uriStr)) {
-      return !_fsState.externalSummaries.linkedMap.containsKey(uriStr);
+        _fsState.externalSummaries.hasUnlinkedUnit(uriStr)) {
+      return _fsState.externalSummaries.isPartUnit(uriStr);
     }
     if (_unlinked2 != null) {
       return !_unlinked2.hasLibraryDirective && _unlinked2.hasPartOfDirective;

pkg/analyzer/lib/src/summary/package_bundle_reader.dart

@@ -7,6 +7,7 @@ import 'dart:math' show min;
 
 import 'package:analyzer/dart/analysis/session.dart';
 import 'package:analyzer/file_system/file_system.dart';
+import 'package:analyzer/src/dart/analysis/driver.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/source_io.dart';
@@ -130,10 +131,17 @@ class InSummaryUriResolver extends UriResolver {
   Source resolveAbsolute(Uri uri, [Uri actualUri]) {
     actualUri ??= uri;
     String uriString = uri.toString();
-    UnlinkedUnit unit = _dataStore.unlinkedMap[uriString];
-    if (unit != null) {
+    if (AnalysisDriver.useSummary2) {
       String summaryPath = _dataStore.uriToSummaryPath[uriString];
-      return new InSummarySource(actualUri, summaryPath);
+      if (summaryPath != null) {
+        return new InSummarySource(actualUri, summaryPath);
+      }
+    } else {
+      UnlinkedUnit unit = _dataStore.unlinkedMap[uriString];
+      if (unit != null) {
+        String summaryPath = _dataStore.uriToSummaryPath[uriString];
+        return new InSummarySource(actualUri, summaryPath);
+      }
     }
     return null;
   }
@@ -193,10 +201,13 @@ class SummaryDataStore {
   final Map<String, LinkedLibrary> linkedMap = <String, LinkedLibrary>{};
 
   /**
-   * Map from the URI of a library to the summary path that contained it.
+   * Map from the URI of a unit to the summary path that contained it.
    */
   final Map<String, String> uriToSummaryPath = <String, String>{};
 
+  final Set<String> _libraryUris = Set<String>();
+  final Set<String> _partUris = Set<String>();
+
   /**
    * List of summary paths.
    */
@@ -224,6 +235,7 @@ class SummaryDataStore {
    */
   void addBundle(String path, PackageBundle bundle) {
     bundles.add(bundle);
+
     for (int i = 0; i < bundle.unlinkedUnitUris.length; i++) {
       String uri = bundle.unlinkedUnitUris[i];
       if (_disallowOverlappingSummaries &&
@@ -239,6 +251,20 @@ class SummaryDataStore {
       String uri = bundle.linkedLibraryUris[i];
       addLinkedLibrary(uri, bundle.linkedLibraries[i]);
     }
+
+    if (bundle.bundle2 != null) {
+      for (var library in bundle.bundle2.libraries) {
+        var libraryUri = library.uriStr;
+        _libraryUris.add(libraryUri);
+        for (var unit in library.units) {
+          var unitUri = unit.uriStr;
+          uriToSummaryPath[unitUri] = path;
+          if (unitUri != libraryUri) {
+            _partUris.add(unitUri);
+          }
+        }
+      }
+    }
   }
 
   /**
@@ -293,7 +319,11 @@ class SummaryDataStore {
    * with the given absolute [uri].
    */
   bool hasLinkedLibrary(String uri) {
-    return linkedMap.containsKey(uri);
+    if (AnalysisDriver.useSummary2) {
+      return _libraryUris.contains(uri);
+    } else {
+      return linkedMap.containsKey(uri);
+    }
   }
 
   /**
@@ -301,7 +331,22 @@ class SummaryDataStore {
    * with the given absolute [uri].
    */
   bool hasUnlinkedUnit(String uri) {
-    return unlinkedMap.containsKey(uri);
+    if (AnalysisDriver.useSummary2) {
+      return uriToSummaryPath.containsKey(uri);
+    } else {
+      return unlinkedMap.containsKey(uri);
+    }
+  }
+
+  /**
+   * Return `true` if the unit with the [uri] is a part unit in the store.
+   */
+  bool isPartUnit(String uri) {
+    if (AnalysisDriver.useSummary2) {
+      return _partUris.contains(uri);
+    } else {
+      return !linkedMap.containsKey(uri);
+    }
   }
 
   void _fillMaps(String path, ResourceProvider resourceProvider) {

pkg/analyzer/test/src/summary/package_bundle_reader_test.dart

@@ -186,6 +186,9 @@ class _PackageBundleMock implements PackageBundle {
   @override
   List<String> unlinkedUnitUris;
 
+  @override
+  LinkedNodeBundle bundle2;
+
   @override
   noSuchMethod(Invocation invocation) {
     throw new StateError('Unexpected invocation of ${invocation.memberName}');

pkg/analyzer_cli/lib/src/build_mode.dart

@@ -195,8 +195,6 @@ class BuildMode with HasContextMixin {
   PackageBundleAssembler assembler;
   final Map<String, UnlinkedUnit> uriToUnit = <String, UnlinkedUnit>{};
 
-  final bool buildSummary2 = false;
-  final bool consumeSummary2 = false;
   final Map<String, ParsedUnitResult> inputParsedUnitResults = {};
   summary2.LinkedElementFactory elementFactory;
 
@@ -277,21 +275,21 @@ class BuildMode with HasContextMixin {
           });
 
           // Build and assemble linked libraries.
-          if (!options.buildSummaryOnlyUnlinked) {
-            // Prepare URIs of unlinked units that should be linked.
-            var unlinkedUris = new Set<String>();
-            for (var bundle in unlinkedBundles) {
-              unlinkedUris.addAll(bundle.unlinkedUnitUris);
-            }
-            for (var src in explicitSources) {
-              unlinkedUris.add('${src.uri}');
-            }
-            // Perform linking.
-            _computeLinkedLibraries(unlinkedUris);
-          }
-
-          if (buildSummary2) {
+          if (AnalysisDriver.useSummary2) {
             _computeLinkedLibraries2();
+          } else {
+            if (!options.buildSummaryOnlyUnlinked) {
+              // Prepare URIs of unlinked units that should be linked.
+              var unlinkedUris = new Set<String>();
+              for (var bundle in unlinkedBundles) {
+                unlinkedUris.addAll(bundle.unlinkedUnitUris);
+              }
+              for (var src in explicitSources) {
+                unlinkedUris.add('${src.uri}');
+              }
+              // Perform linking.
+              _computeLinkedLibraries(unlinkedUris);
+            }
           }
 
           // Write the whole package bundle.
@@ -339,9 +337,6 @@ class BuildMode with HasContextMixin {
    * add them to  the [assembler].
    */
   void _computeLinkedLibraries(Set<String> libraryUris) {
-    // Ensure that summary1 linking is done with summary1 rules.
-    AnalysisDriver.useSummary2 = false;
-
     logger.run('Link output summary', () {
       void trackDependency(String absoluteUri) {
         if (dependencyTracker != null) {
@@ -378,7 +373,6 @@ class BuildMode with HasContextMixin {
    * [inputParsedUnitResults] to produce linked libraries in [assembler].
    */
   void _computeLinkedLibraries2() {
-    AnalysisDriver.useSummary2 = consumeSummary2;
     logger.run('Link output summary2', () {
       var inputLibraries = <summary2.LinkInputLibrary>[];
 
@@ -520,9 +514,6 @@ class BuildMode with HasContextMixin {
     analysisOptions =
         createAnalysisOptionsForCommandLineOptions(options, rootPath);
 
-    // Ensure that FileState prepare summary2 information if necessary.
-    AnalysisDriver.useSummary2 = consumeSummary2;
-
     AnalysisDriverScheduler scheduler = new AnalysisDriverScheduler(logger);
     analysisDriver = new AnalysisDriver(
         scheduler,
@@ -538,7 +529,7 @@ class BuildMode with HasContextMixin {
     declaredVariables = new DeclaredVariables.fromMap(options.definedVariables);
     analysisDriver.declaredVariables = declaredVariables;
 
-    if (buildSummary2) {
+    if (AnalysisDriver.useSummary2) {
       _createLinkedElementFactory();
     }
 
@@ -609,10 +600,13 @@ class BuildMode with HasContextMixin {
       return;
     }
     var result = await analysisDriver.parseFile(source.fullName);
-    inputParsedUnitResults[result.path] = result;
-    UnlinkedUnitBuilder unlinkedUnit = serializeAstUnlinked(result.unit);
-    uriToUnit[absoluteUri] = unlinkedUnit;
-    assembler.addUnlinkedUnit(source, unlinkedUnit);
+    if (AnalysisDriver.useSummary2) {
+      inputParsedUnitResults[result.path] = result;
+    } else {
+      UnlinkedUnitBuilder unlinkedUnit = serializeAstUnlinked(result.unit);
+      uriToUnit[absoluteUri] = unlinkedUnit;
+      assembler.addUnlinkedUnit(source, unlinkedUnit);
+    }
   }
 
   /**
@@ -620,8 +614,6 @@ class BuildMode with HasContextMixin {
    * is sent to a new file at that path.
    */
   Future<void> _printErrors({String outputPath}) async {
-    AnalysisDriver.useSummary2 = consumeSummary2;
-
     await logger.runAsync('Compute and print analysis errors', () async {
       StringBuffer buffer = new StringBuffer();
       var severityProcessor = (AnalysisError error) =>

pkg/analyzer_cli/lib/src/options.dart

@@ -7,6 +7,7 @@ import 'dart:io';
 import 'package:analyzer/file_system/physical_file_system.dart';
 import 'package:analyzer/src/command_line/arguments.dart';
 import 'package:analyzer/src/context/builder.dart';
+import 'package:analyzer/src/dart/analysis/driver.dart';
 import 'package:analyzer/src/dart/analysis/experiments.dart';
 import 'package:analyzer/src/util/sdk.dart';
 import 'package:analyzer_cli/src/ansi.dart' as ansi;
@@ -269,6 +270,11 @@ class CommandLineOptions {
     }
 
     if (options.buildSummaryOnlyUnlinked) {
+      if (AnalysisDriver.useSummary2) {
+        printAndFail('The option --build-summary-only-unlinked can not be used '
+            'together with summary2.');
+        return null; // Only reachable in testing.
+      }
       if (!options.buildSummaryOnly) {
         printAndFail(
             'The option --build-summary-only-unlinked can be used only '

pkg/dev_compiler/lib/src/analyzer/driver.dart

@@ -20,6 +20,7 @@ import 'package:analyzer/src/generated/sdk.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/summary/package_bundle_reader.dart';
 import 'package:analyzer/src/summary/resynthesize.dart';
+import 'package:analyzer/src/summary2/linked_element_factory.dart';
 import 'package:meta/meta.dart';
 
 import '../compiler/shared_command.dart' show sdkLibraryVariables;
@@ -130,11 +131,13 @@ class CompilerAnalysisDriver {
     _extensionTypes ??= ExtensionTypeSet(
       resynthesizerBuilder.context.typeProvider,
       resynthesizerBuilder.resynthesizer,
+      resynthesizerBuilder.elementFactory,
     );
 
     return LinkedAnalysisDriver(
       analysisOptions,
       resynthesizerBuilder.resynthesizer,
+      resynthesizerBuilder.elementFactory,
       sourceFactory,
       resynthesizerBuilder.libraryUris,
       declaredVariables,
@@ -172,6 +175,7 @@ class CompilerAnalysisDriver {
 class LinkedAnalysisDriver {
   final AnalysisOptions analysisOptions;
   final SummaryResynthesizer resynthesizer;
+  final LinkedElementFactory elementFactory;
   final SourceFactory sourceFactory;
   final List<String> libraryUris;
   final DeclaredVariables declaredVariables;
@@ -186,6 +190,7 @@ class LinkedAnalysisDriver {
   LinkedAnalysisDriver(
       this.analysisOptions,
       this.resynthesizer,
+      this.elementFactory,
       this.sourceFactory,
       this.libraryUris,
       this.declaredVariables,
@@ -193,12 +198,22 @@ class LinkedAnalysisDriver {
       this._fsState,
       this._resourceProvider);
 
-  TypeProvider get typeProvider => resynthesizer.typeProvider;
+  TypeProvider get typeProvider {
+    if (resynthesizer != null) {
+      return resynthesizer.typeProvider;
+    } else {
+      return elementFactory.analysisContext.typeProvider;
+    }
+  }
 
   /// True if [uri] refers to a Dart library (i.e. a Dart source file exists
   /// with this uri, and it is not a part file).
   bool _isLibraryUri(String uri) {
-    return resynthesizer.hasLibrarySummary(uri);
+    if (resynthesizer != null) {
+      return resynthesizer.hasLibrarySummary(uri);
+    } else {
+      return elementFactory.isLibraryUri(uri);
+    }
   }
 
   /// Analyzes the library at [uri] and returns the results of analysis for all
@@ -208,16 +223,23 @@ class LinkedAnalysisDriver {
       throw ArgumentError('"$libraryUri" is not a library');
     }
 
+    AnalysisContext analysisContext;
+    if (resynthesizer != null) {
+      analysisContext = resynthesizer.context;
+    } else {
+      analysisContext = elementFactory.analysisContext;
+    }
+
     var libraryFile = _fsState.getFileForUri(Uri.parse(libraryUri));
     var analyzer = LibraryAnalyzer(
         analysisOptions as AnalysisOptionsImpl,
         declaredVariables,
-        resynthesizer.sourceFactory,
+        sourceFactory,
         (uri) => _isLibraryUri('$uri'),
-        resynthesizer.context,
+        analysisContext,
         resynthesizer,
-        null,
-        InheritanceManager2(resynthesizer.typeSystem),
+        elementFactory,
+        InheritanceManager2(analysisContext.typeSystem),
         libraryFile,
         _resourceProvider);
     // TODO(jmesserly): ideally we'd use the existing public `analyze()` method,
@@ -233,6 +255,10 @@ class LinkedAnalysisDriver {
   }
 
   LibraryElement getLibrary(String uri) {
-    return resynthesizer.getLibraryElement(uri);
+    if (resynthesizer != null) {
+      return resynthesizer.getLibraryElement(uri);
+    } else {
+      return elementFactory.libraryOfUri(uri);
+    }
   }
 }

pkg/dev_compiler/lib/src/analyzer/extension_types.dart

@@ -3,11 +3,13 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:collection';
+
 import 'package:analyzer/dart/element/element.dart'
-    show ClassElement, CompilationUnitElement, Element;
+    show ClassElement, CompilationUnitElement, Element, LibraryElement;
 import 'package:analyzer/dart/element/type.dart' show DartType, InterfaceType;
 import 'package:analyzer/src/generated/resolver.dart' show TypeProvider;
 import 'package:analyzer/src/summary/resynthesize.dart';
+import 'package:analyzer/src/summary2/linked_element_factory.dart';
 import 'element_helpers.dart' show getAnnotationName, isBuiltinAnnotation;
 
 /// Contains information about native JS types (those types provided by the
@@ -29,6 +31,7 @@ import 'element_helpers.dart' show getAnnotationName, isBuiltinAnnotation;
 /// `first` to the `Array.prototype`.
 class ExtensionTypeSet {
   final SummaryResynthesizer _resynthesizer;
+  final LinkedElementFactory _elementFactory;
 
   // Abstract types that may be implemented by both native and non-native
   // classes.
@@ -38,7 +41,8 @@ class ExtensionTypeSet {
   final _nativeTypes = HashSet<ClassElement>();
   final _pendingLibraries = HashSet<String>();
 
-  ExtensionTypeSet(TypeProvider types, this._resynthesizer) {
+  ExtensionTypeSet(
+      TypeProvider types, this._resynthesizer, this._elementFactory) {
     // TODO(vsm): Eventually, we want to make this extensible - i.e., find
     // annotations in user code as well.  It would need to be summarized in
     // the element model - not searched this way on every compile.  To make this
@@ -108,14 +112,14 @@ class ExtensionTypeSet {
   }
 
   void _addExtensionTypesForLibrary(String libraryUri, List<String> typeNames) {
-    var library = _resynthesizer.getLibraryElement(libraryUri);
+    var library = _getLibraryByUri(libraryUri);
     for (var typeName in typeNames) {
       _addExtensionType(library.getType(typeName).type);
     }
   }
 
   void _addExtensionTypes(String libraryUri) {
-    var library = _resynthesizer.getLibraryElement(libraryUri);
+    var library = _getLibraryByUri(libraryUri);
     _visitCompilationUnit(library.definingCompilationUnit);
     library.parts.forEach(_visitCompilationUnit);
   }
@@ -124,6 +128,14 @@ class ExtensionTypeSet {
     _pendingLibraries.add(libraryUri);
   }
 
+  LibraryElement _getLibraryByUri(String uriStr) {
+    if (_resynthesizer != null) {
+      return _resynthesizer.getLibraryElement(uriStr);
+    } else {
+      return _elementFactory.libraryOfUri(uriStr);
+    }
+  }
+
   bool _processPending(Element element) {
     if (_pendingLibraries.isEmpty) return false;
     if (element is ClassElement) {