In the new task model, use explicit dependencies on the type provider.

pkg/analyzer/lib/src/task/manager.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.task.manager;
 
 import 'dart:collection';
 
 import 'package:analyzer/src/generated/java_engine.dart';
 import 'package:analyzer/task/model.dart';
@@ skipping 15 matching lines @@
    * analysis root.
    */
   Set<ResultDescriptor> generalResults = new Set<ResultDescriptor>();
 
   /**
    * A list of the results that are to be computed for priority sources.
    */
   Set<ResultDescriptor> priorityResults = new Set<ResultDescriptor>();
 
   /**
+   * Indicates whether any tasks are currently being performed (or building
+   * their inputs).  In debug builds, we use this to ensure that tasks don't
+   * try to make use of the task manager in reentrant fashion.
+   */
+  bool isTaskRunning = false;

[scheglov, 2015/05/13 21:49:09]

I'm not sure that this is the best place for this flag.
TaskManager works like a contains for tasks, not a runner of them.

[Paul Berry, 2015/05/14 17:11:01]

Where do you think would be better?  I'm open to suggestions, but I didn't
really have any better ideas.

I'll land the CL as is for now; I'm happy to do a follow-up if/when we find a
better place.

[scheglov, 2015/05/14 17:13:04]

Maybe WorkOrder or AnalysisDriver.

[Paul Berry, 2015/05/14 17:27:33]

WorkOrder doesn't work because we create fresh work orders all the time--we need
a singleton object in order to verify that we're not reentrant.

AnalysisDriver is a possibility, but it's a bit ugly because it's hard to get to
the AnalysisDriver from the WorkItem.

I've uploaded an alternate version of the patch which uses AnalysisDriver. 
(Unfortunately the delta from patch set 2 is a bit confusing because I also did
a rebase).  PTAL and let me know what you think.

+
+  /**
    * Add the given [result] to the list of results that are to be computed for
    * all sources within an analysis root.
    */
   void addGeneralResult(ResultDescriptor result) {
     generalResults.add(result);
   }
 
   /**
    * Add the given [result] to the list of results that are to be computed for
    * priority sources.
@@ skipping 59 matching lines @@
   /**
    * Given a list of task [descriptors] that can be used to compute some
    * unspecified result, return the descriptor that will compute the result with
    * the least amount of work.
    */
   TaskDescriptor _findBestTask(List<TaskDescriptor> descriptors) {
     // TODO(brianwilkerson) Improve this implementation.
     return descriptors[0];
   }
 }