Delay 'supertype' for ClassElementImpl and EnumElementImpl.

pkg/analyzer/lib/src/context/context.dart

 // Copyright (c) 2015, 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 analyzer.src.context.context;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 448 matching lines @@
             target, iterator.value, false, hintsEnabled, lintsEnabled, sources);
       }
     }
     return new List<Source>.from(sources);
   }
 
   List<Source> get test_priorityOrder => _priorityOrder;
 
   @override
   TypeProvider get typeProvider {
-    // Make sure a task didn't accidentally try to call back into the context
-    // to retrieve the type provider.
-    assert(!driver.isTaskRunning);

[Brian Wilkerson, 2016/06/01 22:23:28]

Instead of removing this completely, would it work to move it after the null
check on line 472, and then ensure that any tasks that might be asking for the
supertype require the type provider?

[Paul Berry, 2016/06/01 22:25:55]

+1 to this.  The reason we added this check in the first place was to avoid
reentrancy into the task manager, and I would like to make sure we are still
successfully avoiding that :)

[scheglov, 2016/06/02 00:20:40]

That's a great idea.
Thank you!
Done.

-
     if (_typeProvider != null) {
       return _typeProvider;
     }
     Source coreSource = sourceFactory.forUri(DartSdk.DART_CORE);
     if (coreSource == null) {
       throw new AnalysisException("Could not create a source for dart:core");
     }
     LibraryElement coreElement = computeLibraryElement(coreSource);
     if (coreElement == null) {
       throw new AnalysisException("Could not create an element for dart:core");
@@ skipping 1730 matching lines @@
     }
     DartSdk sdk = factory.dartSdk;
     if (sdk == null) {
       throw new IllegalArgumentException(
           "The source factory for an SDK analysis context must have a DartUriResolver");
     }
     return new AnalysisCache(
         <CachePartition>[AnalysisEngine.instance.partitionManager.forSdk(sdk)]);
   }
 }