From 50b62d3b19bf8f2d9de9bb7f84b3e5930ff0ee4b Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@qt.io>
Date: Thu, 28 Sep 2023 08:15:05 +0200
Subject: [PATCH 126/147] QPersistentModelIndex: fix UB (op< on unrelated
 pointers)

Pointers can only be legitimately compared with less-than (<) if they
point into the same array (or one past the end). This is decidedly not
the case for heap-allocated objects like
QPersistentModelIndexPrivates, so doing it is UB.

Fix by using std::less, which is guaranteed to be a total order, even
for unrelated pointer values.

Pick-to: 6.6 6.5 6.2 5.15
Change-Id: If04341b4b55784e7732782f3ae829f53b0ceab9c
Reviewed-by: David Faure <david.faure@kdab.com>
(cherry picked from commit 49f9271360e0ef4e624212e442dfcd7765571d60)
---
 src/corelib/itemmodels/qabstractitemmodel.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/corelib/itemmodels/qabstractitemmodel.cpp b/src/corelib/itemmodels/qabstractitemmodel.cpp
index 997a634e76..1c1ca7394d 100644
--- a/src/corelib/itemmodels/qabstractitemmodel.cpp
+++ b/src/corelib/itemmodels/qabstractitemmodel.cpp
@@ -52,6 +52,8 @@
 #include <qdatetime.h>
 #include <qloggingcategory.h>
 
+#include <functional>
+
 #include <limits.h>
 
 QT_BEGIN_NAMESPACE
@@ -213,7 +215,7 @@ bool QPersistentModelIndex::operator<(const QPersistentModelIndex &other) const
     if (d && other.d)
         return d->index < other.d->index;
 
-    return d < other.d;
+    return std::less<>{}(d, other.d);
 }
 
 /*!
-- 
2.40.1