QMetaType: remember whether a type was registered with Q_DECLARE_METATYPE

There are two ways to register a type: using Q_DECLARE_METATYPE(T) and
using qRegisterMetaType<T>("T"). Doing one thing in one translation
unit and another thing in another TU constitutes an ODR violation,
because the value of QMetaTypeId<T>::Defined will differ in the two
TUs.

By adding the information whether a type was declared with
Q_DECLARE_METATYPE to the typeFlags(), such a use will trigger
the existing binary-incompatibility failure that checks for
equality of the incoming type flags with the stored ones (if any).

I had to encode the type as a defaulted function argument in order
to avoid the linker merging instantiations of the function templates
and therefore rendering the detection moot.

Change-Id: I82017caf300458b411cc8ac2f6653536fac64117
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

4 files changed, 161 insertions, 0 deletions

diff --git a/tests/manual/qmetatype/declare_metatype_noninline.cpp b/tests/manual/qmetatype/declare_metatype_noninline.cpp
new file mode 100644
index 0000000000..8054daba06
--- /dev/null
+++ b/tests/manual/qmetatype/declare_metatype_noninline.cpp
@@ -0,0 +1,49 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Marc Mutz <marc.mutz@kdab.com>
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "declare_metatype_noninline.h"
+
+Q_DECLARE_METATYPE(ToBeDeclaredMetaTypeNonInline)
+
+int ToBeDeclaredMetaTypeNonInline::triggerRegistration()
+{
+    return qMetaTypeId<ToBeDeclaredMetaTypeNonInline>();
+}
diff --git a/tests/manual/qmetatype/declare_metatype_noninline.h b/tests/manual/qmetatype/declare_metatype_noninline.h
new file mode 100644
index 0000000000..74244a3fcf
--- /dev/null
+++ b/tests/manual/qmetatype/declare_metatype_noninline.h
@@ -0,0 +1,52 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Marc Mutz <marc.mutz@kdab.com>
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef DECLARE_METATYPE_NONINLINE_H
+#define DECLARE_METATYPE_NONINLINE_H
+
+#include <QtCore/qmetatype.h>
+
+struct ToBeDeclaredMetaTypeNonInline {
+    static int triggerRegistration();
+};
+
+#endif // DECLARE_METATYPE_NONINLINE_H
+
diff --git a/tests/manual/qmetatype/qmetatype.pro b/tests/manual/qmetatype/qmetatype.pro
new file mode 100644
index 0000000000..a4f941e577
--- /dev/null
+++ b/tests/manual/qmetatype/qmetatype.pro
@@ -0,0 +1,5 @@
+CONFIG += testcase
+TARGET = tst_qmetatype_expect_fail
+QT = core
+HEADERS = declare_metatype_noninline.h
+SOURCES = tst_qmetatype.cpp declare_metatype_noninline.cpp
diff --git a/tests/manual/qmetatype/tst_qmetatype.cpp b/tests/manual/qmetatype/tst_qmetatype.cpp
new file mode 100644
index 0000000000..bd17ca260c
--- /dev/null
+++ b/tests/manual/qmetatype/tst_qmetatype.cpp
@@ -0,0 +1,55 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Marc Mutz <marc.mutz@kdab.com>
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QtCore>
+
+#include "declare_metatype_noninline.h"
+
+int main(int argc, char **argv)
+{
+    qDebug("expect no warning here");
+    const int id = qRegisterMetaType<ToBeDeclaredMetaTypeNonInline>("ToBeDeclaredMetaTypeNonInline");
+    qDebug("expect a qfatal now");
+    const int result = ToBeDeclaredMetaTypeNonInline::triggerRegistration();
+    Q_ASSERT(id == result);
+    qDebug("if you read this, check that a qFatal was seen, "
+           "otherwise the test failed.");
+}