From d4eae78e6b34aef6adaa8a1460616b45504c1321 Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@qt.io>
Date: Tue, 19 Sep 2023 10:46:15 +0200
Subject: [PATCH] Check that QMulti{Map,Hash} (still) store in reverse
 insertion order
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It's wrong, but let's not break it unconsciously.

Pick-to: 6.5
Change-Id: Ic3daa7df4db2ef34ff5d08fddecf9a932ad92156
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
(cherry picked from commit 2d052b038d5c3e8ec55ca12b3ba531208a6d3cf1)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
 tests/auto/corelib/tools/qhash/tst_qhash.cpp | 21 +++++++++++++++++
 tests/auto/corelib/tools/qmap/tst_qmap.cpp   | 24 ++++++++++++++++++++
 2 files changed, 45 insertions(+)

diff --git a/tests/auto/corelib/tools/qhash/tst_qhash.cpp b/tests/auto/corelib/tools/qhash/tst_qhash.cpp
index c906924b2b5..977fcc73b78 100644
--- a/tests/auto/corelib/tools/qhash/tst_qhash.cpp
+++ b/tests/auto/corelib/tools/qhash/tst_qhash.cpp
@@ -3,8 +3,10 @@
 
 #include <QTest>
 
+#include <qdebug.h>
 #include <qhash.h>
 #include <qmap.h>
+#include <qscopeguard.h>
 #include <qset.h>
 
 #include <algorithm>
@@ -62,6 +64,7 @@ private slots:
     void eraseValidIteratorOnSharedHash();
     void equal_range();
     void insert_hash();
+    void multiHashStoresInReverseInsertionOrder();
 
     void emplace();
 
@@ -2484,6 +2487,24 @@ void tst_QHash::insert_hash()
     }
 }
 
+void tst_QHash::multiHashStoresInReverseInsertionOrder()
+{
+    const QString strings[] = {
+        u"zero"_s,
+        u"null"_s,
+        u"nada"_s,
+    };
+    {
+        QMultiHash<int, QString> hash;
+        for (const QString &string : strings)
+            hash.insert(0, string);
+        auto printOnFailure = qScopeGuard([&] { qDebug() << hash; });
+        QVERIFY(std::equal(hash.begin(), hash.end(),
+                           std::rbegin(strings), std::rend(strings)));
+        printOnFailure.dismiss();
+    }
+}
+
 void tst_QHash::emplace()
 {
     {
diff --git a/tests/auto/corelib/tools/qmap/tst_qmap.cpp b/tests/auto/corelib/tools/qmap/tst_qmap.cpp
index 577ea1e8989..93bf0b50706 100644
--- a/tests/auto/corelib/tools/qmap/tst_qmap.cpp
+++ b/tests/auto/corelib/tools/qmap/tst_qmap.cpp
@@ -3,7 +3,11 @@
 
 #include <qmap.h>
 #include <QTest>
+
 #include <QDebug>
+#include <QScopeGuard>
+
+using namespace Qt::StringLiterals;
 
 QT_WARNING_DISABLE_DEPRECATED
 
@@ -61,6 +65,8 @@ private slots:
     void removeElementsInMap();
     void toStdMap();
 
+    void multiMapStoresInReverseInsertionOrder();
+
     // Tests for deprecated APIs.
 #if QT_DEPRECATED_SINCE(6, 0)
     void deprecatedInsertMulti();
@@ -2548,6 +2554,24 @@ void tst_QMap::toStdMap()
     toStdMapTestMethod<QMultiMap<int, QString>>(expectedMultiMap);
 }
 
+void tst_QMap::multiMapStoresInReverseInsertionOrder()
+{
+    const QString strings[] = {
+        u"zero"_s,
+        u"null"_s,
+        u"nada"_s,
+    };
+    {
+        QMultiMap<int, QString> map;
+        for (const QString &string : strings)
+            map.insert(0, string);
+        auto printOnFailure = qScopeGuard([&] { qDebug() << map; });
+        QVERIFY(std::equal(map.begin(), map.end(),
+                           std::rbegin(strings), std::rend(strings)));
+        printOnFailure.dismiss();
+    }
+}
+
 #if QT_DEPRECATED_SINCE(6, 0)
 void tst_QMap::deprecatedInsertMulti()
 {