1 files changed, 32 insertions, 0 deletions
diff --git a/src/corelib/tools/qhash.h b/src/corelib/tools/qhash.h
index e99a67d1e3..9dd0e6144d 100644
--- a/src/corelib/tools/qhash.h
+++ b/src/corelib/tools/qhash.h
@@ -509,6 +509,20 @@ private:
     static void deleteNode2(QHashData::Node *node);
 
     static void duplicateNode(QHashData::Node *originalNode, void *newNode);
+
+    bool isValidIterator(const iterator &it) const
+    {
+#if defined(QT_DEBUG) && !defined(Q_HASH_NO_ITERATOR_DEBUG)
+        QHashData::Node *node = it.i;
+        while (node->next)
+            node = node->next;
+        return (static_cast<void *>(node) == d);
+#else
+        Q_UNUSED(it);
+        return true;
+#endif
+    }
+    friend class QSet<Key>;
 };
 
 
@@ -831,9 +845,27 @@ Q_OUTOFLINE_TEMPLATE T QHash<Key, T>::take(const Key &akey)
 template <class Key, class T>
 Q_OUTOFLINE_TEMPLATE typename QHash<Key, T>::iterator QHash<Key, T>::erase(iterator it)
 {
+    Q_ASSERT_X(isValidIterator(it), "QHash::erase", "The specified iterator argument 'it' is invalid");
+
     if (it == iterator(e))
         return it;
 
+    if (d->ref.isShared()) {
+        int bucketNum = (it.i->h % d->numBuckets);
+        iterator bucketIterator(*(d->buckets + bucketNum));
+        int stepsFromBucketStartToIte = 0;
+        while (bucketIterator != it) {
+            ++stepsFromBucketStartToIte;
+            ++bucketIterator;
+        }
+        detach();
+        it = iterator(*(d->buckets + bucketNum));
+        while (stepsFromBucketStartToIte > 0) {
+            --stepsFromBucketStartToIte;
+            ++it;
+        }
+    }
+
     iterator ret = it;
     ++ret;