https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110343
--- Comment #5 from Ed Smith-Rowland <emsr at gcc dot gnu.org> --- Probably should. I'll see how to do that. I might have to set up the lang flag and all that unless someone beats me to it. I was going to say that the error on the stringification is possibly correct. The paper says usage in things _other_ than literals is illegal. Plus, over on gcc I think they have the equivalent thing implemented and I assume they would know.
