[libvirt] [PATCH] build: ask for -std=gnu99 explicitly

[Daniel P. Berrangé]

On Mon, Oct 07, 2019 at 04:27:31PM +0200, Peter Krempa wrote:
> On Mon, Oct 07, 2019 at 15:09:52 +0100, Daniel Berrange wrote:
> > We previously got -std=gnu99 secretly enabled as a side-effect
> > of requesting the 'stdarg' gnulib module. We rely on some
> > extensions from c99/gnu99 and while RHEL-7 supports this, it
> > still defaults to gnu89.  RHEL-7 also supports some newer
> > standards but declares them experimental/incomplete, so sticking
> > with gnu99 is best bet for now & matches historical usage.
> > 
> > Signed-off-by: Daniel P. Berrangé <berrange at redhat.com>
> > ---
> >  m4/virt-compile-warnings.m4 | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/m4/virt-compile-warnings.m4 b/m4/virt-compile-warnings.m4
> > index f9460e82ba..502f7384ff 100644
> > --- a/m4/virt-compile-warnings.m4
> > +++ b/m4/virt-compile-warnings.m4
> > @@ -189,6 +189,10 @@ AC_DEFUN([LIBVIRT_COMPILE_WARNINGS],[
> >        wantwarn="$wantwarn -Werror"
> >      fi
> >  
> > +    # Request the gnu99 standard which is the best choice with
> > +    # gcc 4.8.0
> > +    wantwarn="-std=gnu99"
> > +
> 
> It feels odd to add this via the warning flags variable.
> 
> I know this is a hack until we get rid of the old build system, but I
> think you should at least admit it in the commit message or comment that
> it's deliberate.

It is nothing new, we've long used this file for things that are not mere
warning flags, eg setting FORTIFY_SOURCE or -fstack-protector. Really
its just a bad filename, but its not worth worrying about that at this
point IMHO.

Regards,
Daniel
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