Re: autoconf-2.68: no AC_LANG_SOURCE call detected in body

[Eric Blake]

On 09/23/2010 06:56 AM, Ralf Corsepius wrote:
> Hi,
>
> I am facing a new issue/regression with autoconf-2.68:

That is not a regression, but a feature.  Reread NEWS:

> AC_COMPILE_IFELSE([
> #ifndef FOO
> choke me
> #endif
> ])

You should have used:

AC_COMPILE_IFELSE([AC_LANG_SOURCE([
#ifndef FOO
choke me
#endif
])

> With older autoconfs, autoreconf remains entirely silent.

Not only were they entirely silent, but most likely generated a broken 
configure.  If you don't use AC_LANG_SOURCE, then you don't get the 
benefit of all the prior AC_DEFINEs being implicitly included before the 
body of your test, which leads to documented cases of mis-diagnosing 
whether a feature is present for a given build.

> What is wrong with this configure.ac rsp. how to overcome these warnings?

Use AC_LANG_SOURCE, like the warning told you to do in the first place.

--
Eric Blake   address@hidden    +1-801-349-2682
Libvirt virtualization library http://libvirt.org