https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98055
--- Comment #6 from Martin Sebor <msebor at gcc dot gnu.org> --- (In reply to Paul Smith from comment #5) > Is there some preprocessor magic that lets me know that I'm using GCC's > __builtin_alloc so I can avoid calling alloca(0) in that situation? The following detects support for __builtin_alloca in GCC. __has_builtin is available in GCC 10 and later and all recent versions of Clang. #ifdef __has_builtin # if __has_builtin (__builtin_alloca) # warning have __builtin_alloca # else # warning no __builtin_alloca # endif #else # warning no __has_builtin #endif
