Deprecate calling QList::insert/removeAt with out of bounds index

Users should not call any QList API with indices that are out of
bounds. Deprecate this behavior and make sure users get warnings
in debug mode and assertions if they disable deprecated functionality.

[ChangeLog][Important Behavior Changes] Calling QList::insert() or removeAt()
with an out of bounds index is deprecated and will not be supported in Qt 6
anymore.

Change-Id: I97adecc2e2aabd36ea2cc69e0895d625f78b32a0
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@qt.io>

2 files changed, 20 insertions, 5 deletions

diff --git a/src/corelib/tools/qlist.cpp b/src/corelib/tools/qlist.cpp
index dfebd57e34..3dc962236c 100644
--- a/src/corelib/tools/qlist.cpp
+++ b/src/corelib/tools/qlist.cpp
@@ -847,9 +847,10 @@ void **QListData::erase(void **xi)
 
 /*! \fn template <class T> void QList<T>::insert(int i, const T &value)
 
-    Inserts \a value at index position \a i in the list. If \a i <= 0,
-    the value is prepended to the list. If \a i >= size(), the
-    value is appended to the list.
+    Inserts \a value at index position \a i in the list.
+
+    If \a i == 0, the value is prepended to the list. If \a i == size(),
+    the value is appended to the list.
 
     Example:
     \snippet code/src_corelib_tools_qlistdata.cpp 8
diff --git a/src/corelib/tools/qlist.h b/src/corelib/tools/qlist.h
index 425ffa42a5..ffd470efcd 100644
--- a/src/corelib/tools/qlist.h
+++ b/src/corelib/tools/qlist.h
@@ -580,8 +580,16 @@ inline T &QList<T>::operator[](int i)
   detach(); return reinterpret_cast<Node *>(p.at(i))->t(); }
 template <typename T>
 inline void QList<T>::removeAt(int i)
-{ if(i >= 0 && i < p.size()) { detach();
- node_destruct(reinterpret_cast<Node *>(p.at(i))); p.remove(i); } }
+{
+#if !QT_DEPRECATED_SINCE(5, 15)
+    Q_ASSERT_X(i >= 0 && i < p.size(), "QList<T>::removeAt", "index out of range");
+#elif !defined(QT_NO_DEBUG)
+    if (i < 0 || i >= p.size())
+        qWarning("QList::removeAt(): Index out of range.");
+#endif
+    detach();
+    node_destruct(reinterpret_cast<Node *>(p.at(i))); p.remove(i);
+}
 template <typename T>
 inline T QList<T>::takeAt(int i)
 { Q_ASSERT_X(i >= 0 && i < p.size(), "QList<T>::take", "index out of range");
@@ -676,6 +684,12 @@ inline void QList<T>::prepend(const T &t)
 template <typename T>
 inline void QList<T>::insert(int i, const T &t)
 {
+#if !QT_DEPRECATED_SINCE(5, 15)
+    Q_ASSERT_X(i >= 0 && i <= p.size(), "QList<T>::insert", "index out of range");
+#elif !defined(QT_NO_DEBUG)
+    if (i < 0 || i > p.size())
+        qWarning("QList::insert(): Index out of range.");
+#endif
     if (d->ref.isShared()) {
         Node *n = detach_helper_grow(i, 1);
         QT_TRY {