Check for cyclic type variable bounds.

sdk/lib/_internal/compiler/implementation/enqueue.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.
 
 part of dart2js;
 
 class EnqueueTask extends CompilerTask {
   final ResolutionEnqueuer resolution;
   final CodegenEnqueuer codegen;
 
@@ skipping 375 matching lines @@
     compiler.backend.registerIsCheck(type, this, elements);
   }
 
   void registerAsCheck(DartType type, TreeElements elements) {
     registerIsCheck(type, elements);
     compiler.backend.registerAsCheck(type, elements);
   }
 
   void forEach(f(WorkItem work));
 
+  void forEachPostProcessTask(f(PostProcessTask work)) {}
+
   void logSummary(log(message)) {
     _logSpecificSummary(log);
     nativeEnqueuer.logSummary(log);
   }
 
   /// Log summary specific to the concrete enqueuer.
   void _logSpecificSummary(log(message));
 
   String toString() => 'Enqueuer($name)';
 }
 
 /// [Enqueuer] which is specific to resolution.
 class ResolutionEnqueuer extends Enqueuer {
   /**
    * Map from declaration elements to the [TreeElements] object holding the
    * resolution mapping for the element implementation.
    *
    * Invariant: Key elements are declaration elements.
    */
   final Map<Element, TreeElements> resolvedElements;
 
   final Queue<ResolutionWorkItem> queue;
 
+  /**
+   * A post-processing queue for the resolution phase which is processed
+   * immediately after the resolution queue has been closed.
+   */
+  final Queue<PostProcessTask> postQueue;
+
   ResolutionEnqueuer(Compiler compiler,
                      ItemCompilationContext itemCompilationContextCreator())
       : super('resolution enqueuer', compiler, itemCompilationContextCreator),
         resolvedElements = new Map<Element, TreeElements>(),
-        queue = new Queue<ResolutionWorkItem>();
+        queue = new Queue<ResolutionWorkItem>(),
+        postQueue = new Queue<PostProcessTask>();
 
   bool get isResolutionQueue => true;
 
   bool isProcessed(Element member) => resolvedElements.containsKey(member);
 
   TreeElements getCachedElements(Element element) {
     // TODO(ngeoffray): Get rid of this check.
     if (element.enclosingElement.isClosure()) {
       closureMapping.ClosureClassElement cls = element.enclosingElement;
       element = cls.methodElement;
@@ skipping 80 matching lines @@
     addToWorkList(compiler.createInvocationMirrorElement);
   }
 
   void forEach(f(WorkItem work)) {
     while (!queue.isEmpty) {
       // TODO(johnniwinther): Find an optimal process order for resolution.
       f(queue.removeLast());
     }
   }
 
+  /**
+   * Adds an action to the post-processing queue.
+   *
+   * The action is performed as part of the post-processing immediately after
+   * the resolution queue has been closed. As a consequence, [action] must not
+   * add elements to the resolution queue.
+   */
+  void addPostProcessAction(Element element, PostProcessAction action) {
+    if (queueIsClosed) {
+      throw new SpannableAssertionFailure(element,
+                                          "Resolution work list is closed.");
+    }
+    postQueue.add(new PostProcessTask(element, action));
+  }
+
+  void forEachPostProcessTask(f(PostProcessTask work)) {
+    while (!postQueue.isEmpty) {
+      f(postQueue.removeFirst());
+    }
+  }
+
   void registerJsCall(Send node, ResolverVisitor resolver) {
     nativeEnqueuer.registerJsCall(node, resolver);
   }
 
   void _logSpecificSummary(log(message)) {
     log('Resolved ${resolvedElements.length} elements.');
   }
 }
 
 /// [Enqueuer] which is specific to code generation.
@@ skipping 29 matching lines @@
     while(!queue.isEmpty) {
       // TODO(johnniwinther): Find an optimal process order for codegen.
       f(queue.removeLast());
     }
   }
 
   void _logSpecificSummary(log(message)) {
     log('Compiled ${generatedCode.length} methods.');
   }
 }