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(a)redhat.com&gt; --- 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" +

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(a)redhat.com&gt; > > --- > > 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.