Possible fix for a null-pointer problem

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/instrumentation/instrumentation.dart';
@@ skipping 1499 matching lines @@
       }
     }
     return entries;
   }
 
   void _evaluatePendingFutures() {
     for (AnalysisTarget target in _pendingFutureTargets.keys) {
       CacheEntry cacheEntry = _cache.get(target);
       List<PendingFuture> pendingFutures = _pendingFutureTargets[target];
       for (int i = 0; i < pendingFutures.length;) {
-        if (pendingFutures[i].evaluate(cacheEntry)) {
+        if (cacheEntry == null) {
+          pendingFutures[i].forciblyComplete();

[Paul Berry, 2015/10/21 17:57:34]

After this line, add:

pendingFutures.removeAt(i);

Otherwise we will try to forcibly complete the same futures over and over again
every time _evaluatePendingFutures() is called.

[Brian Wilkerson, 2015/10/21 18:05:01]

Good catch! Done.

[Leaf, 2015/10/21 18:15:47]

This is the same location that I was generally seeing the null cache entry
errors, so likely this will fix it.  I don't know if you want to pursue this
further, but I did observe that if you change the get method to throw an error
if it reaches the end of the method (which is not supposed to happen), then you
get a test failure:

python tools/test.py --host-checked -mrelease -cdart2analyzer -rnone -t240
language/internal_library_test/02

I didn't track it down any further at the time though.

+        } else if (pendingFutures[i].evaluate(cacheEntry)) {
           pendingFutures.removeAt(i);
         } else {
           i++;
         }
       }
     }
   }
 
   /**
    * Return a list containing all of the change notices that are waiting to be
@@ skipping 582 matching lines @@
         new PendingFuture<T>(_context, target, computeValue);
     if (!pendingFuture.evaluate(entry)) {
       _context._pendingFutureTargets
           .putIfAbsent(target, () => <PendingFuture>[])
           .add(pendingFuture);
       scheduleComputation();
     }
     return pendingFuture.future;
   }
 }