http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50982
--- Comment #17 from David Edelsohn <dje at gcc dot gnu.org> 2011-11-04 16:10:22 UTC --- Created attachment 25717 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25717 Pre-processed atomic.cc that compiles The incorrect version of atomic.ii includes more code, but nothing specific to pthread_once_t. I still am trying to understand the nesting, but is an extern "C++" statement resetting the mode that was not occurring before?