Hi Sami,
On 06/11/2017 10:36 AM, Sami Kerola wrote:
On 9 June 2017 at 22:10, Rüdiger Meier <sweet_f_a@xxxxxx> wrote:
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)
Is this a typoo? s/deprecated/fallthrough
# define UL_FALLTHROUGH __attribute__((fallthrough))
# elif __has_cpp_attribute(clang::fallthrough)
# define UL_FALLTHROUGH [[clang::fallthrough]]
I still wonder. Have you really seen such a fallthrough warning from clang?
I've even tried with explicit -Wimplicit-fallthrough but could not get one.
As far as I understood these namespaced "clang::" attributes are for C++ only.
man clang:
Non-standard C++11 Attributes
Clang's non-standard C++11 attributes live in the clang attribute namespace
So IMO it makes no sense to use clang::fallthrough for C code.
# endif
#endif
#ifndef UL_FALLTHROUGH
# define UL_FALLTHROUGH /* FALLTHRU */
#endif
BTW just for cosmetics. Maybe we should rename UL_FALLTHROUGH to __ul_fallthrough
like we have already __ul_calloc_size. IMO it would look more obvious to the reader.
Also I would use it without semicolon because some compilers may complain about
useless ";" statements.
cu,
Rudi
The above is now part of my remote branch '2017wk23'.
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