Vala adds an unused "gpointer boxed;" declaration in the *_get_property function, which makes the C compiler generate a warning with -Wall. This does not seem to affect *_set_property.

ongardie@lappy:~$ valac --version
Vala 0.7.5
ongardie@lappy:~$ cat boxed.vala 
public class Test : GLib.Object {

    public int foo { get; set; }

    public static int main () {
        return 0;
    }
}
ongardie@lappy:~$ valac -X -Wall boxed.vala 
/home/ongardie/boxed.vala.c: In function ‘test_get_property’:
/home/ongardie/boxed.vala.c:124: warning: unused variable ‘boxed’
ongardie@lappy:~$ valac -C boxed.vala 
ongardie@lappy:~$ nl -b a < boxed.c
[...snip...]
    26	struct _TestPrivate {
    27		gint _foo;
    28	};
[...snip...]
    42	gint test_get_foo (Test* self);
    43	void test_set_foo (Test* self, gint value);
[...snip...]
   122	static void test_get_property (GObject * object, guint property_id, GValue * value, GParamSpec * pspec) {
   123		Test * self;
   124		gpointer boxed;
   125		self = TEST (object);
   126		switch (property_id) {
   127			case TEST_FOO:
   128			g_value_set_int (value, test_get_foo (self));
   129			break;
   130			default:
   131			G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
   132			break;
   133		}
   134	}
   135	
   136	
   137	static void test_set_property (GObject * object, guint property_id, const GValue * value, GParamSpec * pspec) {
   138		Test * self;
   139		self = TEST (object);
   140		switch (property_id) {
   141			case TEST_FOO:
   142			test_set_foo (self, g_value_get_int (value));
   143			break;
   144			default:
   145			G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
   146			break;
   147		}
   148	}
   149	
   150	
   151	
   152