QAccessibleWidget: replace QString default arg with overload

We should not use defaulted arguments of non-trivial type, because
their construction and destruction, even if not passed, is repeated at
every call site, producing O(n) executable code.

By overloading out-of-line, we execute the same code at runtime, but
we have only one copy of the arg construction and destruction, in the
library, O(1) executable code production.

Found in API-review of QAccessibleWidgetV2.

Amends the start of the public history.

Can't pick further than (unreleased) 6.10, because this adds a new
symbol.

Task-number: QTBUG-98117
Change-Id: I705bca764992d9e7a2aa1021e0f94006b6817177
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
(cherry picked from commit ab53b1293122518a512335b94491566305280851)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/widgets/accessible/qaccessiblewidget.cpp

@@ -153,15 +153,24 @@ public:
 
 /*!
     Creates a QAccessibleWidget object for widget \a w.
-    \a role and \a name are optional parameters that set the object's
+    \a role is an optional parameter that sets the object's role property.
-    role and name properties.
 */
-QAccessibleWidget::QAccessibleWidget(QWidget *w, QAccessible::Role role, const QString &name)
+QAccessibleWidget::QAccessibleWidget(QWidget *w, QAccessible::Role role)
 : QAccessibleObject(w)
 {
     Q_ASSERT(widget());
     d = new QAccessibleWidgetPrivate();
     d->role = role;
+}
+
+/*!
+    Creates a QAccessibleWidget object for widget \a w.
+    \a role and \a name are optional parameters that set the object's
+    role and name properties.
+*/
+QAccessibleWidget::QAccessibleWidget(QWidget *w, QAccessible::Role role, const QString &name)
+    : QAccessibleWidget(w, role)
+{
     d->name = name;
 }
 
@@ -490,7 +499,7 @@ QAccessibleWidgetV2::QAccessibleWidgetV2(QWidget *object, QAccessible::Role role
 }
 
 QAccessibleWidgetV2::QAccessibleWidgetV2(QWidget *object, QAccessible::Role role)
-    : QAccessibleWidgetV2(object, role, QString())
+    : QAccessibleWidget(object, role)
 {
 }
 

src/widgets/accessible/qaccessiblewidget.h

@@ -19,7 +19,8 @@ class Q_WIDGETS_EXPORT QAccessibleWidget : public QAccessibleObject,
                                            public QAccessibleActionInterface
 {
 public:
-    explicit QAccessibleWidget(QWidget *o, QAccessible::Role r = QAccessible::Client, const QString& name = QString());
+    explicit QAccessibleWidget(QWidget *o, QAccessible::Role r = QAccessible::Client);
+    explicit QAccessibleWidget(QWidget *o, QAccessible::Role r, const QString& name);
     bool isValid() const override;
 
     QWindow *window() const override;