SWT/Devel/Gtk/Sentinel warning

In certain cases, you may encounter a warning: missing sentinel compilation warning. This occurs when dealing with function calls that have a terminator parameter, in order to signify the end of a variable argument length function.

For example, see gtk_file_chooser_dialog_new() defined in OS.java as follows:

 /**
 * @param title cast=(const gchar *),flags=no_out
 * @param parent cast=(GtkWindow *)
 * @param first_button_text cast=(const gchar *),flags=no_out
 * @param terminator cast=(const gchar *),flags=sentinel
 */
 public static final native long /*int*/ _gtk_file_chooser_dialog_new(byte[] title, long /*int*/ parent, int action, long /*int*/ first_button_text, int first_button_id, long /*int*/
     second_button_text, int second_button_id, long /*int*/ terminator);
 public static final long /*int*/ gtk_file_chooser_dialog_new(byte[] title, long /*int*/ parent, int action, long /*int*/ first_button_text, int first_button_id, long /*int*/
     second_button_text, int second_button_id, long /*int*/ terminator) {
       lock.lock();
       try {
           return _gtk_file_chooser_dialog_new(title, parent, action, first_button_text, first_button_id, second_button_text, second_button_id, terminator);
       } finally {
           lock.unlock();
       }
 }

Notice the flags=sentinel for terminator parameter. This flag alerts the compiler to the fact that this is a terminator value, and should be regarded as Null. This is necessary even if the function is only called with a Null value for the terminator. Adding this flag should remove any sentinel warnings for that parameter.

For further reference/information, consult the SWT JNIGen Tool Metadata page.