From a4fd95c51a4347482d6d0a815657d0b5bdaf06db 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: 6.9 6.8 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>
---
 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 cea77ec16b2..ba42ccb7d79 100644
--- a/tests/auto/corelib/tools/qset/tst_qset.cpp
+++ b/tests/auto/corelib/tools/qset/tst_qset.cpp
@@ -33,6 +33,7 @@ private slots:
     void cpp17ctad();
     void remove();
     void removeOnlyDetachesIfSomethingGetsRemoved();
+    void removeIfDoesNotAllowThePredicateToModifyTheElement();
     void contains();
     void containsSet();
     void begin();
@@ -424,6 +425,17 @@ 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;