From 0bed456f47d9c13d0158ee336d4a13bcf3a3bda3 Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@kdab.com>
Date: Sat, 2 May 2020 23:03:39 +0200
Subject: [PATCH] QStandardItemModel: port a local QSet to QDuplicateTracker

Apart from a more fitting, minimal, API, QDuplicateTracker also
transparently uses C++17 pmr::monotonic_buffer_resource to avoid, or
at least reduce, memory allocations.

Change-Id: I59242287debfd1e41c663aa2b88d0d3ea44f43fb
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
---
 src/gui/itemmodels/qstandarditemmodel.cpp | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/src/gui/itemmodels/qstandarditemmodel.cpp b/src/gui/itemmodels/qstandarditemmodel.cpp
index bc76d0ea60..9bb9d57c4e 100644
--- a/src/gui/itemmodels/qstandarditemmodel.cpp
+++ b/src/gui/itemmodels/qstandarditemmodel.cpp
@@ -48,7 +48,7 @@
 #include <QtCore/qstringlist.h>
 #include <QtCore/qbitarray.h>
 #include <QtCore/qmimedata.h>
-
+#include <private/qduplicatetracker_p.h>
 #include <private/qstandarditemmodel_p.h>
 #include <qdebug.h>
 #include <algorithm>
@@ -3114,12 +3114,11 @@ QMimeData *QStandardItemModel::mimeData(const QModelIndexList &indexes) const
 
     //remove duplicates childrens
     {
-        QSet<QStandardItem *> seen;
+        QDuplicateTracker<QStandardItem *> seen;
         while (!stack.isEmpty()) {
             QStandardItem *itm = stack.pop();
-            if (seen.contains(itm))
+            if (seen.hasSeen(itm))
                 continue;
-            seen.insert(itm);
 
             const QVector<QStandardItem*> &childList = itm->d_func()->children;
             for (int i = 0; i < childList.count(); ++i) {