Support FALLTHROUGH macro better in glibc+clang
Looking through the FALLTHROUGH definitions in gnulib, it appears that it has the assumption built-in that glibc will only be built by GCC. Nowadays people are alternatively using (non-Apple) clang to build glibc, see https://www.collabora.com/news-and-blog/blog/2021/09/30/a-tale-of-two-toolchains-and-glibc/ https://www.collabora.com/news-and-blog/blog/2023/01/17/a-brave-new-world-building-glibc-with-llvm/ To help going in this direction, how about this patch? Paul, do you object? 2023-02-26 Bruno Haible Support FALLTHROUGH macro better in glibc+clang. * lib/fnmatch.c (FALLTHROUGH): Use __attribute__ ((__fallthrough__)) also in clang >= 10. * lib/fts.c (FALLTHROUGH): Likewise. * lib/regex_internal.h (FALLTHROUGH): Likewise. diff --git a/lib/fnmatch.c b/lib/fnmatch.c index 7c9c4e0f24..306b967c62 100644 --- a/lib/fnmatch.c +++ b/lib/fnmatch.c @@ -64,7 +64,7 @@ extern int fnmatch (const char *pattern, const char *string, int flags); #endif #ifdef _LIBC -# if __GNUC__ >= 7 +# if (__GNUC__ >= 7) || (__clang_major__ >= 10) # define FALLTHROUGH __attribute__ ((__fallthrough__)) # else # define FALLTHROUGH ((void) 0) diff --git a/lib/fts.c b/lib/fts.c index 78584b2902..388d251252 100644 --- a/lib/fts.c +++ b/lib/fts.c @@ -203,7 +203,7 @@ enum Fts_stat #endif #ifdef _LIBC -# if __GNUC__ >= 7 +# if (__GNUC__ >= 7) || (__clang_major__ >= 10) # define FALLTHROUGH __attribute__ ((__fallthrough__)) # else # define FALLTHROUGH ((void) 0) diff --git a/lib/regex_internal.h b/lib/regex_internal.h index 149ec2e868..d4dae98534 100644 --- a/lib/regex_internal.h +++ b/lib/regex_internal.h @@ -822,7 +822,7 @@ re_string_elem_size_at (const re_string_t *pstr, Idx idx) } #ifdef _LIBC -# if __GNUC__ >= 7 +# if (__GNUC__ >= 7) || (__clang_major__ >= 10) # define FALLTHROUGH __attribute__ ((__fallthrough__)) # else # define FALLTHROUGH ((void) 0)
Re: Support FALLTHROUGH macro better in glibc+clang
Hi Paul, Any objections against this proposed patch from <https://lists.gnu.org/archive/html/bug-gnulib/2023-02/msg00178.html> ? > 2023-02-26 Bruno Haible > > Support FALLTHROUGH macro better in glibc+clang. > * lib/fnmatch.c (FALLTHROUGH): Use __attribute__ ((__fallthrough__)) > also in clang >= 10. > * lib/fts.c (FALLTHROUGH): Likewise. > * lib/regex_internal.h (FALLTHROUGH): Likewise.
Re: Support FALLTHROUGH macro better in glibc+clang
On 2023-02-26 08:43, Bruno Haible wrote: -# if __GNUC__ >= 7 +# if (__GNUC__ >= 7) || (__clang_major__ >= 10) Sorry I didn't see this earlier. Since this is protected by #ifdef _LIBC" it might be better to do this the glibc way. Something like the following, perhaps? # if __GNUC_PREREQ (7,0) || __glibc_has_attribute (__fallthrough__)
Re: Support FALLTHROUGH macro better in glibc+clang
On 2023-03-25 14:24, Paul Eggert wrote: # if __GNUC_PREREQ (7,0) || __glibc_has_attribute (__fallthrough__) Come to think of it this could be simplified further, to just: # if __glibc_has_attribute (__fallthrough__) since GCC started supporting __has_attribute in GCC 5.
Re: Support FALLTHROUGH macro better in glibc+clang
Paul Eggert wrote: > On 2023-03-25 14:24, Paul Eggert wrote: > > # if __GNUC_PREREQ (7,0) || __glibc_has_attribute (__fallthrough__) > > Come to think of it this could be simplified further, to just: > ># if __glibc_has_attribute (__fallthrough__) > > since GCC started supporting __has_attribute in GCC 5. Good point. I'm thus committing this in your name: 2023-03-27 Paul Eggert Support FALLTHROUGH macro better in glibc+clang. * lib/fnmatch.c (FALLTHROUGH): Use __attribute__ ((__fallthrough__)) also in clang >= 10. * lib/fts.c (FALLTHROUGH): Likewise. * lib/regex_internal.h (FALLTHROUGH): Likewise. diff --git a/lib/fnmatch.c b/lib/fnmatch.c index 7c9c4e0f24..32cfb48d0f 100644 --- a/lib/fnmatch.c +++ b/lib/fnmatch.c @@ -64,7 +64,7 @@ extern int fnmatch (const char *pattern, const char *string, int flags); #endif #ifdef _LIBC -# if __GNUC__ >= 7 +# if __glibc_has_attribute (__fallthrough__) # define FALLTHROUGH __attribute__ ((__fallthrough__)) # else # define FALLTHROUGH ((void) 0) diff --git a/lib/fts.c b/lib/fts.c index 794a4f75d7..3fffb45d70 100644 --- a/lib/fts.c +++ b/lib/fts.c @@ -203,7 +203,7 @@ enum Fts_stat #endif #ifdef _LIBC -# if __GNUC__ >= 7 +# if __glibc_has_attribute (__fallthrough__) # define FALLTHROUGH __attribute__ ((__fallthrough__)) # else # define FALLTHROUGH ((void) 0) diff --git a/lib/regex_internal.h b/lib/regex_internal.h index 149ec2e868..ae9257eac0 100644 --- a/lib/regex_internal.h +++ b/lib/regex_internal.h @@ -822,7 +822,7 @@ re_string_elem_size_at (const re_string_t *pstr, Idx idx) } #ifdef _LIBC -# if __GNUC__ >= 7 +# if __glibc_has_attribute (__fallthrough__) # define FALLTHROUGH __attribute__ ((__fallthrough__)) # else # define FALLTHROUGH ((void) 0)