On 9 June 2017 at 22:10, Rüdiger Meier <sweet_f_a@xxxxxx> wrote: > > > On 06/09/2017 01:14 PM, Ruediger Meier wrote: >> >> Hi, >> >> This patch looks a bit ugly, for example: >> >> ## gcc 4.8.1 >> >> CC text-utils/more-more.o >> ../text-utils/more.c: In function ‘command’: >> ../text-utils/more.c:1273:4: warning: empty declaration [enabled by >> default] >> UL_FALLTHROUGH; >> >> ## icc 16.0.0 >> >> text-utils/more.c(1273): warning #1292: unknown attribute "fallthrough" >> UL_FALLTHROUGH; >> ^ >> >>> diff --git a/include/c.h b/include/c.h >>> index a5162b964..8a67b5dfb 100644 >>> --- a/include/c.h >>> +++ b/include/c.h >>> @@ -77,6 +77,24 @@ >>> #endif >>> /* >>> + * Statement Attributes >>> + */ >>> +#if defined(__clang__) >>> +# ifndef __has_cpp_attribute >>> +# define __has_cpp_attribute(x) 0 >>> +# endif >>> +# if __has_cpp_attribute(clang::fallthrough) >>> +# define UL_FALLTHROUGH [[clang::fallthrough]] >>> +# else >>> +# define UL_FALLTHROUGH /* fall through */ >>> +# endif >>> +#elif defined(__GNUC__) || defined(__GNUG__) >>> +# define UL_FALLTHROUGH __attribute__((fallthrough)) >>> +#else >>> +# define UL_FALLTHROUGH /* FALLTHRU */ >>> +#endif >>> + >>> +/* > > > Sorry this was broken. But I've checked now all clang and gcc versions. > Looks > like for clang the warning is only enabled when using C++ (clang++). So the > fallthrough warning appears currently only on gcc>=7 and this works to > disable > it in a compatible way: > > #ifndef __has_cpp_attribute > # define __has_cpp_attribute(x) 0 > #endif > > #if __has_cpp_attribute(fallthrough) > # define UL_FALLTHROUGH __attribute__((fallthrough)) > #else > # define UL_FALLTHROUGH /* fall through */ > #endif Thank you for review Rudi. I had a look of the c.h again and did the change a little bit differently: #ifdef __has_cpp_attribute # if __has_cpp_attribute(deprecated) # define UL_FALLTHROUGH __attribute__((fallthrough)) # elif __has_cpp_attribute(clang::fallthrough) # define UL_FALLTHROUGH [[clang::fallthrough]] # endif #endif #ifndef UL_FALLTHROUGH # define UL_FALLTHROUGH /* FALLTHRU */ #endif The above is now part of my remote branch '2017wk23'. -- Sami Kerola http://www.iki.fi/kerolasa/ -- To unsubscribe from this list: send the line "unsubscribe util-linux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
