Make the roleNames a virtual accessor.

This is consistent with the rest of the API of QAbstractItemModel
(which is virtual) and removes the need for code like this
in the constructor (where it doesn't belong):

QHash<int, QByteArray> myRoleNames = roleNames();
myRoleNames.insert(Qt::UserRole + 1, "myCustomRole");
setRoleNames(myRoleNames);

in favor of

MyModel::roleNames() const {
  QHash<int, QByteArray> myRoleNames = QAbstractItemModel::roleNames();
  myRoleNames.insert(Qt::UserRole + 1, "myCustomRole");
  return myRoleNames;
}

which is consistent with all other QAIM API (eg, flags()).

This is a source compatible change.

Change-Id: I7e1ce17f8dab2292c4c7b6dbd3c09ec71b5c793b
Reviewed-by: David Faure <faure@kde.org>
Reviewed-by: Marius Bugge Monsen <marius@cutehacks.com>

src/corelib/itemmodels/qabstractitemmodel.cpp

@@ -2132,6 +2132,7 @@ QSize QAbstractItemModel::span(const QModelIndex &) const
 
 /*!
     \since 4.6
+    \obsolete
 
     Sets the model's role names to \a roleNames.
 
@@ -2142,7 +2143,11 @@ QSize QAbstractItemModel::span(const QModelIndex &) const
 
     \sa roleNames()
 */
-void QAbstractItemModel::setRoleNames(const QHash<int,QByteArray> &roleNames)
+
+/*!
+    \internal
+ */
+void QAbstractItemModel::doSetRoleNames(const QHash<int,QByteArray> &roleNames)
 {
     Q_D(QAbstractItemModel);
     d->roleNames = roleNames;
@@ -2155,7 +2160,7 @@ void QAbstractItemModel::setRoleNames(const QHash<int,QByteArray> &roleNames)
 
     \sa setRoleNames()
 */
-const QHash<int,QByteArray> &QAbstractItemModel::roleNames() const
+QHash<int,QByteArray> QAbstractItemModel::roleNames() const
 {
     Q_D(const QAbstractItemModel);
     return d->roleNames;

src/corelib/itemmodels/qabstractitemmodel.h

@@ -222,7 +222,7 @@ public:
                                   Qt::MatchFlags(Qt::MatchStartsWith|Qt::MatchWrap)) const;
     virtual QSize span(const QModelIndex &index) const;
 
-    const QHash<int,QByteArray> &roleNames() const;
+    virtual QHash<int,QByteArray> roleNames() const;
 
 #ifdef Q_NO_USING_KEYWORD
     inline QObject *parent() const { return QObject::parent(); }
@@ -302,9 +302,16 @@ protected:
     void changePersistentIndexList(const QModelIndexList &from, const QModelIndexList &to);
     QModelIndexList persistentIndexList() const;
 
-    void setRoleNames(const QHash<int,QByteArray> &roleNames);
+#if QT_DEPRECATED_SINCE(5,0)
+    QT_DEPRECATED void setRoleNames(const QHash<int,QByteArray> &roleNames)
+    {
+        doSetRoleNames(roleNames);
+    }
+#endif
 
 private:
+    void doSetRoleNames(const QHash<int,QByteArray> &roleNames);
+
     Q_DECLARE_PRIVATE(QAbstractItemModel)
     Q_DISABLE_COPY(QAbstractItemModel)
 };

tests/auto/corelib/itemmodels/qabstractitemmodel/tst_qabstractitemmodel.cpp

@@ -112,6 +112,8 @@ private slots:
 
     void testChildrenLayoutsChanged();
 
+    void testRoleNames();
+
 private:
     DynamicTreeModel *m_model;
 };
@@ -1976,5 +1978,31 @@ void tst_QAbstractItemModel::testChildrenLayoutsChanged()
     }
 }
 
+class OverrideRoleNames : public QStringListModel
+{
+    Q_OBJECT
+public:
+    OverrideRoleNames(QObject *parent = 0)
+      : QStringListModel(parent)
+    {
+
+    }
+
+    QHash<int, QByteArray> roleNames() const
+    {
+        QHash<int, QByteArray> roles = QStringListModel::roleNames();
+        roles.insert(Qt::UserRole + 2, "custom");
+        return roles;
+    }
+};
+
+void tst_QAbstractItemModel::testRoleNames()
+{
+    QAbstractItemModel *model = new OverrideRoleNames(this);
+    QHash<int, QByteArray> roles = model->roleNames();
+    QVERIFY(roles.contains(Qt::UserRole + 2));
+    QVERIFY(roles.value(Qt::UserRole + 2) == "custom");
+}
+
 QTEST_MAIN(tst_QAbstractItemModel)
 #include "tst_qabstractitemmodel.moc"