Sparse has support for a subset of GCC's large collection of builtin functions. As for GCC, it's not easy to know which builtins are supported in which versions. clang has a good solution to this problem: it adds the checking macro __has_builtin(<name>) which evaluates to 1 if <name> is a builtin function supported by the compiler and 0 otherwise. It can be used like: #if __has_builtin(__builtin_clz) #define clz(x) __builtin_clz(x) #else ... #endif It's possible or probable that GCC will have this soon too: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66970 Add support for this __has_builtin() macro by extending the evaluation of preprocessor expressions very much like it is done to support defined(). Note: Some function-like builtin features, like __builtin_offset(), are considered as a kind of keyword/operator and processed as such. These are *not* considered as builtins by __has_builtin(). Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>