[vala] D-Bus: Require class prerequisite for dbus interfaces

[Luca Bruno <lucabru src gnome org>]

commit 2c9bb02e005856dd580ad59250a6fce53b072d4c
Author: Luca Bruno <lucabru src gnome org>
Date:   Thu Jun 2 20:08:24 2011 +0200

    D-Bus: Require class prerequisite for dbus interfaces
    
    Fixes bug 651715.

 codegen/valagdbusservermodule.vala |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)
---
diff --git a/codegen/valagdbusservermodule.vala b/codegen/valagdbusservermodule.vala
index 8c1507d..6593d08 100644
--- a/codegen/valagdbusservermodule.vala
+++ b/codegen/valagdbusservermodule.vala
@@ -1225,7 +1225,13 @@ public class Vala.GDBusServerModule : GDBusClientModule {
 		alloc_data.add_argument (new CCodeConstant ("3"));
 		ccode.add_assignment (new CCodeIdentifier ("data"), alloc_data);
 
-		var ref_object = new CCodeFunctionCall (new CCodeIdentifier (sym.get_ref_function ()));
+		var ref_function = sym.get_ref_function ();
+		if (sym is Interface && ref_function == null) {
+			Report.error (sym.source_reference, "missing class prerequisite for interface `%s', add GLib.Object to interface declaration if unsure".printf (sym.get_full_name ()));
+			return;
+		}
+
+		var ref_object = new CCodeFunctionCall (new CCodeIdentifier (ref_function));
 		ref_object.add_argument (new CCodeIdentifier ("object"));
 		ccode.add_assignment (new CCodeElementAccess (new CCodeIdentifier ("data"), new CCodeConstant ("0")), ref_object);