http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56411
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-02-20 19:34:21 UTC --- Well, if you are already changing the code, just put there space instead. While right now _ and s are the only characters allowed to start a user defined literal, I'm pretty sure in the future more will come.
