On 2013-06-20 10:51 -0700, Russ Allbery wrote:
> Nick Bowler <nbowler@xxxxxxxxxxxxxxxx> writes:
> > C11 also provides max_align_t, which is *probably* what you are looking
> > for but obviously isn't available everywhere. Anyway, on older
> > implementations without max_align_t, the following type is probably a
> > "good enough" substitute for it:
>
> > union {
> > char a;
> > short b;
> > int c;
> > long d;
> > long long e;
> > float f;
> > double g;
> > long double h;
> > void *i;
> > }
>
> I would add a function pointer, but yes.
Good idea.
> > You could use AC_CHECK_TYPE to test for max_align_t, then use
> > AC_CHECK_ALIGNOF on the above monster if it is not available.
>
> > You may also want to test for long long availability before
> > including it in the union...
>
> And long double, which IIRC is more of a portability issue than long long.
FWIW, the autoconf manual has the following to say in §5.9.1 "Particular
Type Checks"[1]:
[AC_TYPE_LONG_DOUBLE] is obsolescent, as current C compilers support
long double. New programs need not use this macro.
[1] https://gnu.org/software/autoconf/manual/autoconf.html#Particular-Types
Cheers,
--
Nick Bowler, Elliptic Technologies (http://www.elliptictech.com/)
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