http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51795
--- Comment #24 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-01-27 22:01:14 UTC --- There aren't if afterwards you don't submit a patch to GCC ;) Seriously, I'm pretty sure that there are many implementations around and Boost would be by and large ok, but normally it's much better and straightforward from the legal point of view if you look only at GPL code, eg, the GNU Scientific Library would be perfect.
