[libvirt] gnulib compiler warning detection broken on RHEL5 autoconf

Eric Blake eblake at redhat.com
Tue Jul 26 18:14:05 UTC 2011

On 07/26/2011 10:05 AM, Eric Blake wrote:
> On 07/26/2011 04:45 AM, Daniel P. Berrange wrote:
>> I was wondering why I didn't see any compile warnings from the broken
>> gnutls code on RHEL5 when I noticed that we were building without any
>> compiler warning flags at all.
>> It seems configure fails on RHEL5 vintage autoconf
>> checking whether compiler handles -Wall... ./configure: line 75468:
>> ${$as_gl_Warn+set}: bad substitution
> Yuck. I'll take a look (it may be that older autoconf has a bug, and I
> merely need to backport a workaround for that bug fix).
>> I'm guessing it is the gl_WARN_ADD() macro that is at fault somehow.
> Very possible, in fact, it may be a case of gl_WARN_ADD using an
> autoconf macro and assuming newer semantics, where a bit more work is
> needed to guarantee support with autoconf 2.59.

Yep.  Bug is in gnulib.

When using AS_VAR_PUSHDEF, autoconf 2.59 requires that all subsequent 
uses of that placeholder be used _unquoted_ until the AS_VAR_POPDEF. 
Newer autoconf fixed things to work with the typical autoconf quoting 
rules, but gnulib wants to work with autoconf 2.59, so it must use the 
older syntax.  I'll be pushing a gnulib fix shortly.

Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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