http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53769
--- Comment #1 from joseph at codesourcery dot com <joseph at codesourcery dot com> 2012-06-25 18:55:22 UTC --- On Mon, 25 Jun 2012, patrick.pelissier at gmail dot com wrote: > When building a C program with -std=c11, GCC doesn't define > __STDC_NO_THREADS__ & __STDC_NO_ATOMIC__ whereas it doesn't support theses > features (yet) and still defines __STDC_VERSION__ to 201112L. C11 support is documented as substantially incomplete. I believe there is work in progress on a branch to add support for the atomics interfaces (likely including GCC providing stdatomic.h given how closely related that is to the compiler, even though it's not a header required for freestanding implmentations). As for the threading functionality, that's substantially a library issue and glibc 2.16 will predefine __STDC_NO_THREADS__ in stdc-predef.h to declare the lack of library support as of that glibc version. The final piece is implicit preinclusion of stdc-predef.h so that the macros do appear to be defined right from the start of the translation unit - I have a 4.8 version of my patch <http://gcc.gnu.org/ml/gcc-patches/2009-04/msg01444.html> but need to debug problems with its interaction with PCH.
