QObject: add setProperty() overload taking rvalue QVariant

Instead of duplicating the long-ish implementation, simply pass the
variant as pointers to const and mutable, and implement a runtime
version of std::forward.

[ChangeLog][QtCore][QObject] Added setProperty() overload taking an
rvalue QVariant.

Fixes: QTBUG-113281
Task-number: QTBUG-112762
Change-Id: Ifdc8f626ad5db138073474c3bd95ec7308c4396b
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

src/corelib/compat/removed_api.cpp

@@ -509,6 +509,8 @@ QByteArray QMessageAuthenticationCode::hash(const QByteArray &msg, const QByteAr
                 qToByteArrayViewIgnoringNull(key), method);
 }
 
+#include "qobject.h" // inlined API
+
 #include "qrunnable.h"
 
 QRunnable *QRunnable::create(std::function<void()> functionToRun)

src/corelib/kernel/qobject.cpp

@@ -4094,6 +4094,8 @@ int QObjectPrivate::signalIndex(const char *signalName,
  *****************************************************************************/
 
 /*!
+  \fn bool QObject::setProperty(const char *name, const QVariant &value)
+
   Sets the value of the object's \a name property to \a value.
 
   If the property is defined in the class using Q_PROPERTY then
@@ -4114,9 +4116,17 @@ int QObjectPrivate::signalIndex(const char *signalName,
 
   \sa property(), metaObject(), dynamicPropertyNames(), QMetaProperty::write()
 */
-bool QObject::setProperty(const char *name, const QVariant &value)
+
+/*!
+  \fn bool QObject::setProperty(const char *name, QVariant &&value)
+  \since 6.6
+  \overload setProperty
+*/
+
+bool QObject::doSetProperty(const char *name, const QVariant *lvalue, QVariant *rvalue)
 {
     Q_D(QObject);
+    const auto &value =*lvalue;
     const QMetaObject *meta = metaObject();
     if (!name || !meta)
         return false;
@@ -4135,12 +4145,18 @@ bool QObject::setProperty(const char *name, const QVariant &value)
         } else {
             if (idx == -1) {
                 d->extraData->propertyNames.append(name);
-                d->extraData->propertyValues.append(value);
+                if (rvalue)
+                    d->extraData->propertyValues.append(std::move(*rvalue));
+                else
+                    d->extraData->propertyValues.append(*lvalue);
             } else {
                 if (value.userType() == d->extraData->propertyValues.at(idx).userType()
                         && value == d->extraData->propertyValues.at(idx))
                     return false;
-                d->extraData->propertyValues[idx] = value;
+                if (rvalue)
+                    d->extraData->propertyValues[idx] = std::move(*rvalue);
+                else
+                    d->extraData->propertyValues[idx] = *lvalue;
             }
         }
 
@@ -4155,7 +4171,7 @@ bool QObject::setProperty(const char *name, const QVariant &value)
         qWarning("%s::setProperty: Property \"%s\" invalid,"
                  " read-only or does not exist", metaObject()->className(), name);
 #endif
-    return p.write(this, value);
+    return rvalue ? p.write(this, std::move(*rvalue)) : p.write(this, *lvalue);
 }
 
 /*!

src/corelib/kernel/qobject.h

@@ -292,7 +292,9 @@ public:
     void dumpObjectTree() const;
     void dumpObjectInfo() const;
 
+    QT_CORE_INLINE_SINCE(6, 6)
     bool setProperty(const char *name, const QVariant &value);
+    inline bool setProperty(const char *name, QVariant &&value);
     QVariant property(const char *name) const;
     QList<QByteArray> dynamicPropertyNames() const;
     QBindingStorage *bindingStorage() { return &d_ptr->bindingStorage; }
@@ -345,6 +347,8 @@ protected:
 
 private:
     void doSetObjectName(const QString &name);
+    bool doSetProperty(const char *name, const QVariant *lvalue, QVariant *rvalue);
+
     Q_DISABLE_COPY(QObject)
     Q_PRIVATE_SLOT(d_func(), void _q_reregisterTimers(void *))
 
@@ -363,6 +367,17 @@ inline QMetaObject::Connection QObject::connect(const QObject *asender, const ch
                                             const char *amember, Qt::ConnectionType atype) const
 { return connect(asender, asignal, this, amember, atype); }
 
+#if QT_CORE_INLINE_IMPL_SINCE(6, 6)
+bool QObject::setProperty(const char *name, const QVariant &value)
+{
+    return doSetProperty(name, &value, nullptr);
+}
+#endif // inline since 6.6
+bool QObject::setProperty(const char *name, QVariant &&value)
+{
+    return doSetProperty(name, &value, &value);
+}
+
 template <class T>
 inline T qobject_cast(QObject *object)
 {