QtFuture: Prevent whenAll()/whenAny() from creating reference cycles

whenAll() and whenAny() create a shared context object which is
referenced by the continuation lambda. The refcount of context is only
correctly managed when it is copied non-const to the lambda's
capture list.

Fixes: QTBUG-116731
Pick-to: 6.6 6.6.0
Change-Id: I8e79e1a0dc867f69bbacf1ed873f353a18f6ad38
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

1 files changed, 34 insertions, 0 deletions

diff --git a/tests/auto/corelib/thread/qfuture/tst_qfuture.cpp b/tests/auto/corelib/thread/qfuture/tst_qfuture.cpp
index 128a9bd837..f54ea940f7 100644
--- a/tests/auto/corelib/thread/qfuture/tst_qfuture.cpp
+++ b/tests/auto/corelib/thread/qfuture/tst_qfuture.cpp
@@ -5011,6 +5011,40 @@ void tst_QFuture::continuationsDontLeak()
         QVERIFY(continuationIsRun);
     }
     QCOMPARE(InstanceCounter::count, 0);
+
+    {
+        // QTBUG-116731: Must pass with ASan enabled
+        bool continuationIsRun = false;
+        auto f = QtFuture::makeReadyValueFuture(42);
+        QtFuture::whenAll(f).then([&](auto) { continuationIsRun = true; });
+        QVERIFY(continuationIsRun);
+    }
+
+    {
+        // QTBUG-116731: Must pass with ASan enabled
+        bool continuationIsRun = false;
+        auto f = QtFuture::makeReadyValueFuture(42);
+        QList fs{f};
+        QtFuture::whenAll(fs.begin(), fs.end()).then([&](auto) { continuationIsRun = true; });
+        QVERIFY(continuationIsRun);
+    }
+
+    {
+        // QTBUG-116731: Must pass with ASan enabled
+        bool continuationIsRun = false;
+        auto f = QtFuture::makeReadyValueFuture(42);
+        QtFuture::whenAny(f).then([&](auto) { continuationIsRun = true; });
+        QVERIFY(continuationIsRun);
+    }
+
+    {
+        // QTBUG-116731: Must pass with ASan enabled
+        bool continuationIsRun = false;
+        auto f = QtFuture::makeReadyValueFuture(42);
+        QList fs{f};
+        QtFuture::whenAny(fs.begin(), fs.end()).then([&](auto) { continuationIsRun = true; });
+        QVERIFY(continuationIsRun);
+    }
 }
 
 // This test checks that we do not get use-after-free