On Wed, 7 Oct 2015, Michael Petch wrote:
On 2015-10-06 14:00, Russ Allbery wrote:
/*
* __attribute__ is available in gcc 2.5 and later, but only with gcc 2.7
* could you use the __format__ form of the attributes, which is what we use
* (to avoid confusion with other macros).
*/
#ifndef __attribute__
# if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 7)
# define __attribute__(spec) /* empty */
# endif
#endif
Hi Guys,
Thanks for the information. Russ, I was considering doing this the way
Bison seems to deal with __attribute__ . The generated code looks like:
#ifndef YY_ATTRIBUTE
# if (defined __GNUC__ \
&& (2 < __GNUC__ || (__GNUC__ == 2 && 96 <= __GNUC_MINOR__))) \
|| defined __SUNPRO_C && 0x5110 <= __SUNPRO_C
# define YY_ATTRIBUTE(Spec) __attribute__(Spec)
# else
# define YY_ATTRIBUTE(Spec) /* empty */
# endif
#endif
Based on this I was considering something like:
#ifndef __attribute__
# if (defined __GNUC__ \
&& (2 < __GNUC__ || (__GNUC__ == 2 && 96 <= __GNUC_MINOR__))) \
|| defined __SUNPRO_C && 0x5110 <= __SUNPRO_C
# define __attribute__(Spec) /* empty */
# endif
#endif
It seems to also handle Sun compilers as well. Anyone have any
objections to the latter solution?
There is a ax_c___attribute__.m4 macro in the autoconf archive that
handles this totally differently, by checking if __attribute__(unused)
compiles.
This may be a little careless since gnubg uses it for other things like
alignment. Maybe the macro could be changed so that it optionally takes a
list of attributes to check.
I have no idea if an approach is better. It probably doesn't matter much.
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