Library Cycle invalidation

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

Index: pkg/analyzer/lib/src/task/driver.dart
diff --git a/pkg/analyzer/lib/src/task/driver.dart b/pkg/analyzer/lib/src/task/driver.dart
index 3231454d46fd79688b02692f2a3d02666af9ba35..b725042b36fc1c5495f486aa98432c20bdb6cae0 100644
--- a/pkg/analyzer/lib/src/task/driver.dart
+++ b/pkg/analyzer/lib/src/task/driver.dart
@@ -473,6 +473,14 @@ abstract class ExtendedAnalysisContext implements InternalAnalysisContext {
  */
 class InfiniteTaskLoopException extends AnalysisException {
   /**
+   * A concrete cyclic path of [TargetedResults] within the [dependencyCycle],
+   * `null` if no such path exists.  All nodes in the path are in the
+   * dependencyCycle, but the path is not guaranteed to cover the
+   * entire cycle.
+   */
+  final List<TargetedResult> cyclicPath;

[Leaf, 2015/10/19 22:32:27]

Not sure if this is the right way to surface this.  I wrote some debugging code
(see model.dart) that computes an actual concrete path through the
dependencyCycle, which I found made debugging the issue much simpler since there
are often a very large number of edges on each node in the cycle.  I thought it
would be worthwhile to keep that code around.  If preferred though, I can take
it out, or surface it in a different way.

[Brian Wilkerson, 2015/10/19 23:01:40]

If it makes debugging easier without hurting performance in the non-error case,
then it should stay in.

+
+  /**
    * If a dependency cycle was found while computing the inputs for the task,
    * the set of [WorkItem]s contained in the cycle (if there are overlapping
    * cycles, this is the set of all [WorkItem]s in the entire strongly
@@ -484,7 +492,8 @@ class InfiniteTaskLoopException extends AnalysisException {
    * Initialize a newly created exception to represent a failed attempt to
    * perform the given [task] due to the given [dependencyCycle].
    */
-  InfiniteTaskLoopException(AnalysisTask task, this.dependencyCycle)
+  InfiniteTaskLoopException(AnalysisTask task, this.dependencyCycle,
+      [this.cyclicPath])
       : super(
             'Infinite loop while performing task ${task.descriptor.name} for ${task.target}');
 }