On 12/12/2013 02:02 PM, Julien ÉLIE wrote:
> Hi all,
>
> When using AC_CHECK_HEADERS([filename]), a HAVE_FILENAME (with uppercase chars)
> variable is defined to 1 if the filename header is found.
> Characters not suitable for a variable name in filename are mapped to underscores.
>
> I have a question about how to deal with looking for two different headers that
> lead to the same HAVE_FILENAME variable.
> For instance: how to properly search for gdbm/ndbm.h and gdbm-ndbm.h?
Ugh, there's no clean way to do that with the standard macros. Who
named these header files, and can they be convinced to improve their
naming in the future?
>
> Using:
>
> AC_CHECK_HEADERS([gdbm/ndbm.h gdbm-ndbm.h], [break])
>
> does not help much.
Unfortunately true.
> As the result of the search is cached in $ac_cv_header_filename, maybe
> using the following piece of code is the expected way to deal with the issue?
Yep, multiple AC_CHECK_HEADER with manual actions on success is the best
you can do, rather than AC_CHECK_HEADERS and its automatic actions.
>
>
> AC_CHECK_HEADER([gdbm/ndbm.h])
Unfortunately, AC_CHECK_HEADER short-circuits if the cache is already
populated. And since the collision is not just on the HAVE_GDBM_NDBM_H
preprocessor name, but ALSO on the $ac_cv_header_gdbm_ndbm_h shell
variable, you are liable to get wrong behavior on secondary runs when
caching is enabled ('./configure -C'). To properly distinguish between
the two names, you'll have to completely ignore the pre-set cache names,
and instead wrap the check inside a cache name that you control.
> AS_IF([test x"$ac_cv_header_gdbm_ndbm_h" != xno],
> [AC_DEFINE([HAVE_GDBM_NDBM_H], [1],
> [Define if you have the <gdbm/ndbm.h> header file.])],
> [AS_UNSET([ac_cv_header_gdbm_ndbm_h])
> AC_CHECK_HEADER([gdbm-ndbm.h])
> AS_IF([test x"$ac_cv_header_gdbm_ndbm_h" != xno],
> [AC_DEFINE([HAVE_GDBM_NDBM_H_DASH], [1],
> [Define if you have the <gdbm-ndbm.h> header file.])])])
>
>
>
> If you know a better way to do that, I would be interested in hearing it.
> Thanks beforehand,
>
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
Attachment:
signature.asc
Description: OpenPGP digital signature
_______________________________________________ Autoconf mailing list Autoconf@xxxxxxx https://lists.gnu.org/mailman/listinfo/autoconf
