1 files changed, 34 insertions, 1 deletions
diff --git a/tests/auto/corelib/thread/qfuturesynchronizer/tst_qfuturesynchronizer.cpp b/tests/auto/corelib/thread/qfuturesynchronizer/tst_qfuturesynchronizer.cpp
index fe84ec1ae4..62ad4f872a 100644
--- a/tests/auto/corelib/thread/qfuturesynchronizer/tst_qfuturesynchronizer.cpp
+++ b/tests/auto/corelib/thread/qfuturesynchronizer/tst_qfuturesynchronizer.cpp
@@ -1,5 +1,5 @@
 // Copyright (C) 2016 The Qt Company Ltd.
-// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
 
 #include <QTest>
 
@@ -13,6 +13,7 @@ class tst_QFutureSynchronizer : public QObject
 
 private Q_SLOTS:
     void construction();
+    void setFutureAliasingExistingMember();
     void addFuture();
     void cancelOnWait();
     void clearFutures();
@@ -33,6 +34,38 @@ void tst_QFutureSynchronizer::construction()
     QCOMPARE(synchronizerWithFuture.futures().size(), 1);
 }
 
+void tst_QFutureSynchronizer::setFutureAliasingExistingMember()
+{
+    //
+    // GIVEN: a QFutureSynchronizer with one QFuture:
+    //
+    QFutureSynchronizer synchronizer(QtFuture::makeReadyValueFuture(42));
+
+    //
+    // WHEN: calling setFuture() with an alias of the QFuture already in `synchronizer`:
+    //
+    for (int i = 0; i < 2; ++i) {
+        // The next line triggers -Wdangling-reference, but it's a FP because
+        // of implicit sharing. We cannot keep a copy of synchronizer.futures()
+        // around to avoid the warning, as the extra copy would cause a detach()
+        // of m_futures inside setFuture() with the consequence that `f` no longer
+        // aliases an element in m_futures, which is the goal of this test.
+QT_WARNING_PUSH
+#if defined(Q_CC_GNU_ONLY) && Q_CC_GNU >= 1301
+QT_WARNING_DISABLE_GCC("-Wdangling-reference")
+#endif
+        const auto &f = synchronizer.futures().constFirst();
+QT_WARNING_POP
+        synchronizer.setFuture(f);
+    }
+
+    //
+    // THEN: it didn't crash
+    //
+    QCOMPARE(synchronizer.futures().size(), 1);
+    QCOMPARE(synchronizer.futures().constFirst().result(), 42);
+}
+
 void tst_QFutureSynchronizer::addFuture()
 {
     QFutureSynchronizer<void> synchronizer;