Fix for a bug Andrew Reynolds found for iterators that affects empty CDList<> objects that allocate from ContextMemoryAllocator<>. Iterators were broken in that begin() != end() for empty lists (again---only those that allocated space from ContextMemoryAllocator<>). Added a unit test for this, too. Thanks Andy!

1 files changed, 5 insertions, 1 deletions

diff --git a/src/context/cdlist_context_memory.h b/src/context/cdlist_context_memory.h
index 20d672d31..2fd1ceb8c 100644
--- a/src/context/cdlist_context_memory.h
+++ b/src/context/cdlist_context_memory.h
@@ -476,7 +476,11 @@ public:
    * Returns an iterator pointing to the first item in the list.
    */
   const_iterator begin() const {
-    return const_iterator(&d_headSegment, 0);
+    // This looks curious, but we have to make sure that begin() == end()
+    // for an empty list, and begin() == (head,0) for a nonempty one.
+    // Since the segment spill-over is implemented in
+    // iterator::operator++(), let's reuse it. */
+    return ++const_iterator(&d_headSegment, -1);
   }
 
   /**