QCollator: enable move semantics

This necessitates adding d==0 checks in QCollator. By documenting that
moved-from instances can only be assigned to or destroyed, we can
limit the functions in which to check for d==0 to the assignment
operator and the destructor.

Doing otherwise would destroy all advantages of move semantics by
introducing a heap allocation to re-populate other.d.

Add a test for this (QCollator didn't have any before).

Change-Id: Ic6ff202072822bebfd5e48259c3d0fa345a63118
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

5 files changed, 129 insertions, 3 deletions

diff --git a/src/corelib/tools/qcollator.cpp b/src/corelib/tools/qcollator.cpp
index cfb5fe77ae..80d330bfca 100644
--- a/src/corelib/tools/qcollator.cpp
+++ b/src/corelib/tools/qcollator.cpp
@@ -99,7 +99,7 @@ QCollator::QCollator(const QCollator &other)
  */
 QCollator::~QCollator()
 {
-    if (!d->ref.deref())
+    if (d && !d->ref.deref())
         delete d;
 }
 
@@ -109,14 +109,34 @@ QCollator::~QCollator()
 QCollator &QCollator::operator=(const QCollator &other)
 {
     if (this != &other) {
-        if (!d->ref.deref())
+        if (d && !d->ref.deref())
             delete d;
         d = other.d;
-        d->ref.ref();
+        if (d) d->ref.ref();
     }
     return *this;
 }
 
+/*
+    \fn void QCollator::QCollator(QCollator &&other)
+
+    Move constructor. Moves from \a other into this collator.
+
+    Note that a moved-from QCollator can only be destroyed or assigned
+    to. The effect of calling other functions than the destructor or
+    one of the assignment operators is undefined.
+*/
+
+/*
+    \fn QCollator &QCollator::operator=(QCollator &&other)
+
+    Move-assigns from \a other to this collator.
+
+    Note that a moved-from QCollator can only be destroyed or assigned
+    to. The effect of calling other functions than the destructor or
+    one of the assignment operators is undefined.
+*/
+
 /*!
     \fn void QCollator::swap(QCollator &other)
 
diff --git a/src/corelib/tools/qcollator.h b/src/corelib/tools/qcollator.h
index e5abc91967..1007aa7623 100644
--- a/src/corelib/tools/qcollator.h
+++ b/src/corelib/tools/qcollator.h
@@ -85,6 +85,12 @@ public:
     QCollator(const QCollator &);
     ~QCollator();
     QCollator &operator=(const QCollator &);
+#ifdef Q_COMPILER_RVALUE_REFS
+    QCollator(QCollator &&other)
+        : d(other.d) { other.d = 0; }
+    QCollator &operator=(QCollator &&other)
+    { swap(other); return *this; }
+#endif
 
     void swap(QCollator &other)
     { qSwap(d, other.d); }
diff --git a/tests/auto/corelib/tools/qcollator/qcollator.pro b/tests/auto/corelib/tools/qcollator/qcollator.pro
new file mode 100644
index 0000000000..3c5987ffa0
--- /dev/null
+++ b/tests/auto/corelib/tools/qcollator/qcollator.pro
@@ -0,0 +1,7 @@
+CONFIG += testcase parallel_test
+TARGET = tst_qcollator
+QT = core testlib
+SOURCES = tst_qcollator.cpp
+DEFINES += QT_NO_CAST_TO_ASCII
+contains(QT_CONFIG,icu):DEFINES += QT_USE_ICU
+DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0
diff --git a/tests/auto/corelib/tools/qcollator/tst_qcollator.cpp b/tests/auto/corelib/tools/qcollator/tst_qcollator.cpp
new file mode 100644
index 0000000000..3df8422a34
--- /dev/null
+++ b/tests/auto/corelib/tools/qcollator/tst_qcollator.cpp
@@ -0,0 +1,92 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** 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 <QtTest/QtTest>
+
+#include <qlocale.h>
+#include <qcollator.h>
+
+#include <cstring>
+
+class tst_QCollator : public QObject
+{
+    Q_OBJECT
+
+private Q_SLOTS:
+    void moveSemantics();
+};
+
+#ifdef Q_COMPILER_RVALUE_REFS
+static bool dpointer_is_null(QCollator &c)
+{
+    char mem[sizeof c];
+    using namespace std;
+    memcpy(mem, &c, sizeof c);
+    for (size_t i = 0; i < sizeof c; ++i)
+        if (mem[i])
+            return false;
+    return true;
+}
+#endif
+
+void tst_QCollator::moveSemantics()
+{
+#ifdef Q_COMPILER_RVALUE_REFS
+    const QLocale de_AT(QLocale::German, QLocale::Austria);
+
+    QCollator c1(de_AT);
+    QCOMPARE(c1.locale(), de_AT);
+
+    QCollator c2(std::move(c1));
+    QCOMPARE(c2.locale(), de_AT);
+    QVERIFY(dpointer_is_null(c1));
+
+    c1 = std::move(c2);
+    QCOMPARE(c1.locale(), de_AT);
+    QVERIFY(dpointer_is_null(c2));
+#else
+    QSKIP("The compiler is not in C++11 mode or does not support move semantics.");
+#endif
+}
+
+QTEST_APPLESS_MAIN(tst_QCollator)
+
+#include "tst_qcollator.moc"
diff --git a/tests/auto/corelib/tools/tools.pro b/tests/auto/corelib/tools/tools.pro
index e920813db2..286afdfd18 100644
--- a/tests/auto/corelib/tools/tools.pro
+++ b/tests/auto/corelib/tools/tools.pro
@@ -8,6 +8,7 @@ SUBDIRS=\
     qbytedatabuffer \
     qcache \
     qchar \
+    qcollator \
     qcommandlineparser \
     qcontiguouscache \
     qcryptographichash \