[Vala] gtk 3 vapi bug?

[Nor Jaidi Tuah <norjaidi tuah ubd edu bn>]

version: 0.12.1

The following:
        var filter = new Gtk.FileFilter ();
        filter.add_pattern ("*");
        filter.set_name (_("All files"));

is compiled to:
        _tmp2_ = gtk_file_filter_new ();
        filter = g_object_ref_sink (_tmp2_);
        gtk_file_filter_add_pattern (filter, "*");
        _tmp3_ = _ ("All files");
        gtk_buildable_set_name ((GtkBuildable*) filter, _tmp3_);

I expect the last line to be:
        gtk_file_filter_set_name (filter, _tmp3_);

Due to this bug, the file dialog shows "Untitled filter".
The dialog shows the expected "All files" entry if I tweak
the generated c file to use gtk_file_filter_set_name.

Is this a known bug?

hand
Nor Jaidi Tuah