http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50455
--- Comment #5 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-09-19 12:31:58 UTC --- I'm pretty sure that this is one of those cases where the user violates the ODR, thus undefined behavior, but diagnostics isn't required, exactly because would have to produced at *link* time. You should search Bugzilla for closed PRs having to do with violations of the One Definition Rule, there are duplicates, for sure.
