GDate copy problem

gdate.c

/* Compile with:
 * gcc `pkg-config --cflags --libs glib-2.0 gobject-2.0` gdate.c
 */
#include <glib-object.h>
#include <stdlib.h>
#include <stdio.h>

#define FOO_TYPE_BAR             (foo_bar_get_type ())
G_DECLARE_FINAL_TYPE(FooBar, foo_bar, FOO, BAR, GObject)

typedef struct _FooBar
{
    GObject parent;
    GDate date;
} FooBar;

G_DEFINE_TYPE(FooBar,foo_bar, G_TYPE_OBJECT);

enum {
    PROP_0,
    PROP_DATE,
    N_PROPERTIES
};
static GParamSpec *obj_properties[N_PROPERTIES] = { NULL, };

static void foo_bar_set_property(GObject      *object,
                                 guint         property_id,
                                 const GValue *value,
                                 GParamSpec   *pspec)
{
    FooBar *self = FOO_BAR (object);

    switch (property_id) {
        case PROP_DATE:
            self->date = *(GDate*)g_value_get_boxed(value);
            break;
        default:
            G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
            break;
    }
}


static void
foo_bar_get_property (GObject    *object,
                      guint       property_id,
                      GValue     *value,
                      GParamSpec *pspec)
{
    FooBar *self = FOO_BAR (object);

    switch (property_id) {
        case PROP_DATE:
            if (g_date_valid(&self->date))
                g_value_set_boxed (value, &self->date);
            else {
                GDate *d = g_date_new();
                g_value_take_boxed (value, d);
            }
            break;
        default:
            /* We don't have any other property... */
            G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
            break;
    }
}

static void
foo_bar_class_init (FooBarClass *klass)
{
    GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
    gobject_class->set_property = foo_bar_set_property;
    gobject_class->get_property = foo_bar_get_property;

    obj_properties[PROP_DATE] =
        g_param_spec_boxed ("date", "Date", "Its a date", G_TYPE_DATE, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS);
    g_object_class_install_properties (gobject_class,
                                       N_PROPERTIES,
                                       obj_properties);
}

static void
foo_bar_init (FooBar *self)
{
    g_date_clear(&self->date, 1);
}

FooBar *foo_bar_new(void)
{
    return g_object_new(FOO_TYPE_BAR, NULL);
}

int main()
{
    FooBar *bar = foo_bar_new();
    GDate *d;
    g_object_get(G_OBJECT(bar), "date", &d, NULL);
    return 0;
}