From c1825660aa87ec9c76ce6de4013e80660bc5ab40 Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@qt.io>
Date: Fri, 17 Jan 2025 16:11:21 +0100
Subject: [PATCH] tst_QSet: check whether QSet::removeIf() can modify elements

It can't, pfew. Was wondering for a moment, but of course, even the
QSet::iterator is really a const_iterator.

Pick-to: 6.5 6.2
Change-Id: I85caa64c1caca6d77569aa2ceb868a4aa0e5578d
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Reviewed-by: Magdalena Stojek <magdalena.stojek@qt.io>
Reviewed-by: Lena Biliaieva <lena.biliaieva@qt.io>
(cherry picked from commit a4fd95c51a4347482d6d0a815657d0b5bdaf06db)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
(cherry picked from commit 9120bb9e0393bd10e73510d0103bc330f5b92696)
---
 tests/auto/corelib/tools/qset/tst_qset.cpp | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/tests/auto/corelib/tools/qset/tst_qset.cpp b/tests/auto/corelib/tools/qset/tst_qset.cpp
index 5c86d496cb..389105b79d 100644
--- a/tests/auto/corelib/tools/qset/tst_qset.cpp
+++ b/tests/auto/corelib/tools/qset/tst_qset.cpp
@@ -30,6 +30,7 @@ private slots:
     void cpp17ctad();
     void remove();
     void removeOnlyDetachesIfSomethingGetsRemoved();
+    void removeIfDoesNotAllowThePredicateToModifyTheElement();
     void contains();
     void containsSet();
     void begin();
@@ -394,6 +395,17 @@ void tst_QSet::removeOnlyDetachesIfSomethingGetsRemoved()
     QVERIFY(copy.isDetached());
 }
 
+void tst_QSet::removeIfDoesNotAllowThePredicateToModifyTheElement()
+{
+    QSet<int> set = {0, 1, 2, 3};
+    set.removeIf([](auto &&e) {
+            if constexpr (!std::is_const_v<std::remove_reference_t<decltype(e)>>)
+                e *= 2;
+            return false;
+        });
+    QCOMPARE(set, QSet({0, 1, 2, 3}));
+}
+
 void tst_QSet::contains()
 {
     QSet<QString> set1;