https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100993
--- Comment #3 from joseph at codesourcery dot com <joseph at codesourcery dot com> --- Rejecting __builtin_* declarations was previously discussed in bug 32455. If we do, it would probably be worth testing building various software with the patched GCC to see what issues arise. For many purposes, __sync_* and __atomic_* are built-in function namespaces just like __builtin_* (see builtins.c:is_builtin_name). However, functions with such names are definitely defined in libgcc and libatomic, and quite possibly might be defined elsewhere.
