https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79301
--- Comment #3 from Anders Kaseorg <andersk at mit dot edu> --- (In reply to Jakub Jelinek from comment #2) > I think right now you need to use > #ifdef __has_cpp_attribute > # if __has_cpp_attribute(fallthrough) >= __cplusplus > [[fallthrough]]; Surely you intended* #if __has_cpp_attribute(fallthrough) && __cplusplus >= __has_cpp_attribute(fallthrough)? But neither version helps in current g++-7, where __cplusplus is 201402 (C++14) or 201500 (C++17), while __has_cpp_attribute(fallthrough) is greater than both: 201603. (* Yes, this is confusing, and I would suggest that this confusion is already a good argument for __has_cpp_attribute doing the language standard comparison itself rather than foisting it off on the programmer. That is, __has_cpp_attribute(fallthrough) should return 201500 (C++17 and higher) or 0 (C++14 and lower))
