http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17729
--- Comment #21 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-01-23 15:30:25 UTC --- The problem with testing for duplicate diagnostics is by now well known, I guess. What I couldn't figure out from the audit trail was whether the fix itself was ready to go in or not, the trail badly lacked information. Anyway, many thanks for adding it now. I suppose I should not assign the bug to you? Or you actually feel like giving what Jason suggested a try?
