Fix typo in ListMixin.insertAll.

sdk/lib/collection/list.dart

 // Copyright (c) 2013, 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 dart.collection;
 
 /**
  * Abstract implementation of a list.
  *
  * `ListBase` can be used as a base class for implementing the `List` interface.
@@ skipping 458 matching lines @@
 
   E removeAt(int index) {
     E result = this[index];
     setRange(index, this.length - 1, this, index + 1);
     length--;
     return result;
   }
 
   void insertAll(int index, Iterable<E> iterable) {
     RangeError.checkValueInInterval(index, 0, length, "index");
-    if (iterable is EfficientLength) {
+    if (iterable is! EfficientLength || identical(iterable, this)) {

[Søren Gjesse, 2015/06/01 11:37:57]

Are these cased covered by tests? I guess that we only have tests where
"identical" is hit which also has EfficientLength.

[Lasse Reichstein Nielsen, 2015/06/01 13:13:10]

Probably not. It's hard to test because it only affects performance, not
behavior. There should still be coverage for the code, but it wouldn't have
caught the inverted is-test here.
Since this object is a List which always has EfficientLength, identical implies
"is EfficientLength".

       iterable = iterable.toList();
     }
     int insertionLength = iterable.length;
     // There might be errors after the length change, in which case the list
     // will end up being modified but the operation not complete. Unless we
     // always go through a "toList" we can't really avoid that.
     this.length += insertionLength;
+    if (iterable.length != insertionLength) {
+      // If the iterable's length is linked to this list's length somehow,
+      // we can't insert one in the other.
+      this.length -= insertionLength;
+      throw new ConcurrentModificationError(iterable);
+    }
     setRange(index + insertionLength, this.length, this, index);
     setAll(index, iterable);
   }
 
   void setAll(int index, Iterable<E> iterable) {
     if (iterable is List) {
       setRange(index, index + iterable.length, iterable);
     } else {
       for (E element in iterable) {
         this[index++] = element;
       }
     }
   }
 
   Iterable<E> get reversed => new ReversedListIterable<E>(this);
 
   String toString() => IterableBase.iterableToFullString(this, '[', ']');
 }