Fix UB in tst_QSharedPointer::basics()

Binding a reference to the nullptr is undefined
behavior.

Just skip that particular test when 'ptr' is null.

Found by UBSan:
  tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp:258:32: runtime error: reference binding to null pointer of type 'struct Data'

Change-Id: I125588b9d269a6f76716d660d03142f409513885
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@theqtcompany.com>
Reviewed-by: Lars Knoll <lars.knoll@theqtcompany.com>
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp b/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp
index 7741803224..7538eaf378 100644
--- a/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp
+++ b/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp
@@ -246,8 +246,10 @@ void tst_QSharedPointer::basics()
 
         QCOMPARE(ptr.data(), aData);
         QCOMPARE(ptr.operator->(), aData);
-        Data &dataReference = *ptr;
-        QCOMPARE(&dataReference, aData);
+        if (!isNull) {
+            Data &dataReference = *ptr;
+            QCOMPARE(&dataReference, aData);
+        }
 
         QVERIFY(ptr == aData);
         QVERIFY(!(ptr != aData));