AC_CHECK_SIZEOF (was: Re: [patch 09/17] struct iovec)

[John Vandenberg <ja...@gmail.com>]

On 7/12/06, Justin Erenkrantz <ju...@erenkrantz.com> wrote:
> On 4/14/06, John Mark Vandenberg <ja...@gmail.com> wrote:
> > The change to build/apr_common.m4 allows APR_CHECK_SIZEOF_EXTENDED
> > to be called with a space in the argument.
>
> This is committed in r421074.  (Do you have any clue what those P and
> p's were for?)

At the time I put together the patches I wasn't able to figure that
out.  I've now traced it back to aclocal.m4 rev 59473 [1], and it
appears to be derived from the autoconf macro
AC_CHECK_SIZEOF/AC_SIZEOF_TYPE [2] -- P and p are still given special
meaning in the latest autoconf.

m4sugar/m4sh.m4:
as_tr_cpp="sed y%*$as_cr_letters%P$as_cr_LETTERS%;s%[[^_$as_cr_alnum]]%_%g"

If I am understanding this correctly, it is used to better
differentiate "char" from "char *".

1. http://mail-archives.apache.org/mod_mbox/httpd-cvs/199911.mbox/%3C19991113000726.15620.qmail@hyperreal.org%3E
2. http://cvs.savannah.gnu.org/viewcvs/autoconf/autoconf/acgeneral.m4?r1=1.45&r2=1.46

--
John