Don't increase the reference count if dynamic_cast failed

If the dynamic_cast failed in QSharedPointer::dynamicCast or
qSharedPointerDynamicCast, we should avoid creating the QSharedPointer
that shares the weak and strong reference counts. In Qt 5, this does
not imply a leak since the original pointer is stored internally for
deletion. In Qt 4 it implies a leak under certain circumstances, which
this change fixes.

Task-number: QTBUG-28924
Change-Id: Id2de140de4cf676461e14b201ad250c53666b79d
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp b/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp
index 9edcb8e787..f9fffaa71c 100644
--- a/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp
+++ b/tests/auto/corelib/tools/qsharedpointer/tst_qsharedpointer.cpp
@@ -50,6 +50,7 @@
 
 #include "externaltests.h"
 #include "forwarddeclared.h"
+#include "nontracked.h"
 #include "wrapper.h"
 
 #include <stdlib.h>
@@ -88,6 +89,7 @@ private slots:
     void dynamicCastDifferentPointers();
     void dynamicCastVirtualBase();
     void dynamicCastFailure();
+    void dynamicCastFailureNoLeak();
 #endif
     void constCorrectness();
     void customDeleter();
@@ -1066,6 +1068,11 @@ void tst_QSharedPointer::dynamicCastFailure()
     QCOMPARE(int(refCountData(baseptr)->weakref.load()), 1);
     QCOMPARE(int(refCountData(baseptr)->strongref.load()), 1);
 }
+
+void tst_QSharedPointer::dynamicCastFailureNoLeak()
+{
+    NonTracked::dynamicCastFailureNoLeak();
+}
 #endif
 
 void tst_QSharedPointer::constCorrectness()