Re: build-crossgcc.sh for gcc3.2.3?

[Dan Kegel <dank at kegel dot com>]

Bill Gatliff wrote:
> Dan:
>
> > Plus, it's nice to be able to use attributes on function pointers :-)
>
> Ooh, do tell!  Got an example or two?

Sure.  I have a logging system that lets users pass me a function
pointer for use as the log destination.  Users then log errors
by doing something like
  DPRINT("the %d is %s\n", id, status_str);
which expands to
  (*dprint_fn)(__LINE__, __FILE__, __FUNCTION__, "the %d is %s\n", id, status_str);

With older compilers, I can't mark that global function pointer with
the attributes needed to catch format string mismatches, so use
of DPRINT ends up riskier than using printf.  With newer gcc's,
I can give that nice typechecking by adding
__attribute__((format (printf, 5, 6)))
in front of the pointer declaration.

BTW, to make this compile on older gcc's, I wrap attribute in a macro:

#define __GCC_VERSION(major,minor,patchlevel)  (((major)*10000)+(minor*100)+(patchlevel))
#define __GCCV __GCC_VERSION(__GNUC__,__GNUC_MINOR__,__GNUC_PATCHLEVEL__)

#if defined(__GNUC__) && (__GCCV >= __GCC_VERSION(3,2,0))
#define attribute(...) __attribute__(__VA_ARGS__)
#else
#define attribute(...)
#endif

- Dan

--
Dan Kegel
http://www.kegel.com
http://counter.li.org/cgi-bin/runscript/display-person.cgi?user=78045


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