http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56677
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> 2013-03-21 13:17:15 UTC --- This is because ratio_divide is a struct, as required by earlier C++0x drafts, not an alias template as required by the final standard. It's already fixed for 4.8
