qom: Add object_property_set_default_list()

This function provides a default for properties that are accessed using
the list visitor interface. The default is always an empty list.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-ID: <20231109174240.72376-10-kwolf@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

include/qom/object.h

@@ -1093,6 +1093,14 @@ void object_property_set_default_bool(ObjectProperty *prop, bool value);
  */
 void object_property_set_default_str(ObjectProperty *prop, const char *value);
 
+/**
+ * object_property_set_default_list:
+ * @prop: the property to set
+ *
+ * Set the property default value to be an empty list.
+ */
+void object_property_set_default_list(ObjectProperty *prop);
+
 /**
  * object_property_set_default_int:
  * @prop: the property to set

qom/object.c

@@ -31,6 +31,7 @@
  * of the QOM core on QObject?  */
 #include "qom/qom-qobject.h"
 #include "qapi/qmp/qbool.h"
+#include "qapi/qmp/qlist.h"
 #include "qapi/qmp/qnum.h"
 #include "qapi/qmp/qstring.h"
 #include "qemu/error-report.h"
@@ -1588,6 +1589,11 @@ void object_property_set_default_str(ObjectProperty *prop, const char *value)
     object_property_set_default(prop, QOBJECT(qstring_from_str(value)));
 }
 
+void object_property_set_default_list(ObjectProperty *prop)
+{
+    object_property_set_default(prop, QOBJECT(qlist_new()));
+}
+
 void object_property_set_default_int(ObjectProperty *prop, int64_t value)
 {
     object_property_set_default(prop, QOBJECT(qnum_from_int(value)));