Make QArrayData::shared_null zero terminated.

This is expected by QByteArray and QString

Change-Id: Ib668b144bdc0d2c793018c8f8d794f249eaf935c
Reviewed-by: João Abecasis <joao.abecasis@nokia.com>

3 files changed, 17 insertions, 10 deletions

diff --git a/src/corelib/tools/qarraydata.cpp b/src/corelib/tools/qarraydata.cpp
index 8498d0e4d5..f1b88d5051 100644
--- a/src/corelib/tools/qarraydata.cpp
+++ b/src/corelib/tools/qarraydata.cpp
@@ -46,10 +46,17 @@
 
 QT_BEGIN_NAMESPACE
 
-const QArrayData QArrayData::shared_null = { Q_REFCOUNT_INITIALIZE_STATIC, 0, 0, 0, 0 };
+const QArrayData QArrayData::shared_null[2] = {
+    { Q_REFCOUNT_INITIALIZE_STATIC, 0, 0, 0, sizeof(QArrayData) }, // shared null
+    /* zero initialized terminator */};
 
-static const QArrayData qt_array_empty = { Q_REFCOUNT_INITIALIZE_STATIC, 0, 0, 0, 0 };
-static const QArrayData qt_array_unsharable_empty = { { Q_BASIC_ATOMIC_INITIALIZER(0) }, 0, 0, 0, 0 };
+static const QArrayData qt_array[3] = {
+    { Q_REFCOUNT_INITIALIZE_STATIC, 0, 0, 0, sizeof(QArrayData) }, // shared empty
+    { { Q_BASIC_ATOMIC_INITIALIZER(0) }, 0, 0, 0, sizeof(QArrayData) }, // unsharable empty
+    /* zero initialized terminator */};
+
+static const QArrayData &qt_array_empty = qt_array[0];
+static const QArrayData &qt_array_unsharable_empty = qt_array[1];
 
 QArrayData *QArrayData::allocate(size_t objectSize, size_t alignment,
         size_t capacity, AllocationOptions options)
diff --git a/src/corelib/tools/qarraydata.h b/src/corelib/tools/qarraydata.h
index b4cefe6729..ae4cbc3081 100644
--- a/src/corelib/tools/qarraydata.h
+++ b/src/corelib/tools/qarraydata.h
@@ -115,7 +115,8 @@ struct Q_CORE_EXPORT QArrayData
     static void deallocate(QArrayData *data, size_t objectSize,
             size_t alignment);
 
-    static const QArrayData shared_null;
+    static const QArrayData shared_null[2];
+    static QArrayData *sharedNull() { return const_cast<QArrayData*>(shared_null); }
 };
 
 Q_DECLARE_OPERATORS_FOR_FLAGS(QArrayData::AllocationOptions)
@@ -169,8 +170,7 @@ struct QTypedArrayData
     static QTypedArrayData *sharedNull()
     {
         Q_STATIC_ASSERT(sizeof(QTypedArrayData) == sizeof(QArrayData));
-        return static_cast<QTypedArrayData *>(
-                const_cast<QArrayData *>(&QArrayData::shared_null));
+        return static_cast<QTypedArrayData *>(QArrayData::sharedNull());
     }
 };
 
diff --git a/tests/auto/corelib/tools/qarraydata/tst_qarraydata.cpp b/tests/auto/corelib/tools/qarraydata/tst_qarraydata.cpp
index 9bfbac0017..4bd04f9bc3 100644
--- a/tests/auto/corelib/tools/qarraydata/tst_qarraydata.cpp
+++ b/tests/auto/corelib/tools/qarraydata/tst_qarraydata.cpp
@@ -50,9 +50,9 @@ struct SharedNullVerifier
 {
     SharedNullVerifier()
     {
-        Q_ASSERT(QArrayData::shared_null.ref.isStatic());
-        Q_ASSERT(QArrayData::shared_null.ref.isShared());
-        Q_ASSERT(QArrayData::shared_null.ref.isSharable());
+        Q_ASSERT(QArrayData::shared_null[0].ref.isStatic());
+        Q_ASSERT(QArrayData::shared_null[0].ref.isShared());
+        Q_ASSERT(QArrayData::shared_null[0].ref.isSharable());
     }
 };
 
@@ -159,7 +159,7 @@ void tst_QArrayData::referenceCounting()
 
 void tst_QArrayData::sharedNullEmpty()
 {
-    QArrayData *null = const_cast<QArrayData *>(&QArrayData::shared_null);
+    QArrayData *null = const_cast<QArrayData *>(QArrayData::shared_null);
     QArrayData *empty = QArrayData::allocate(1, Q_ALIGNOF(QArrayData), 0);
 
     QVERIFY(null->ref.isStatic());