Hi Eric,
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?
Well, for instance libgdbm-dev in Debian provides
/usr/include/gdbm-ndbm.h whereas gdbm-devel in Red Hat provides
/usr/include/gdbm/ndbm.h...
Maybe other distributions are using other names. (I have not checked.)
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 $ac_cv_header_gdbm_ndbm_h shell
variable, you are liable to get wrong behavior on secondary runs when
caching is enabled ('./configure -C'). To properly distinguish between
the two names, you'll have to completely ignore the pre-set cache names,
and instead wrap the check inside a cache name that you control.
Oh, that's a pretty good point. Thanks for hinting at it.
Isn't calling AS_UNSET([ac_cv_header_gdbm_ndbm_h]) enough before the two
AC_CHECK_HEADER calls?
I do not understand well what you mean by wrapping the check inside a
cache name that I control.
Do I also have to unset HAVE_GDBM_NDBM_H and HAVE_GDBM_NDBM_H_DASH?
(Are they also cached values when set with AC_DEFINE?)
If all these removals are not enough, what more should I do?
AS_IF([test x"$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.])])])
--
Julien ÉLIE
« – Nous ne connaissons pas leur langue, donc, sous aucun prétexte
il ne faut parler aux Goths !
– Mais on peut leur taper dessus ? » (Astérix)
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