http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54898
--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> 2012-10-12 10:16:19 UTC --- What happens is that we merge wchar_t that is a main variant in one TU with wchar_t that is not a main variant in another TU. I have a patch.