https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114007
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Not to mention that predefining __has_cpp_attribute in such a public header isn't a good idea. They should take example from xxhash which does #ifdef __has_attribute # define XXH_HAS_ATTRIBUTE(x) __has_attribute(x) #else # define XXH_HAS_ATTRIBUTE(x) 0 #endif /* C-language Attributes are added in C23. */ #if defined(__STDC_VERSION__) && (__STDC_VERSION__ > 201710L) && defined(__has_c_attribute) # define XXH_HAS_C_ATTRIBUTE(x) __has_c_attribute(x) #else # define XXH_HAS_C_ATTRIBUTE(x) 0 #endif #if defined(__cplusplus) && defined(__has_cpp_attribute) # define XXH_HAS_CPP_ATTRIBUTE(x) __has_cpp_attribute(x) #else # define XXH_HAS_CPP_ATTRIBUTE(x) 0 #endif #if XXH_HAS_C_ATTRIBUTE(x) # define XXH_FALLTHROUGH [[fallthrough]] #elif XXH_HAS_CPP_ATTRIBUTE(x) # define XXH_FALLTHROUGH [[fallthrough]] #elif XXH_HAS_ATTRIBUTE(__fallthrough__) # define XXH_FALLTHROUGH __attribute__ ((fallthrough)) #else # define XXH_FALLTHROUGH #endif
