Re: [Qemu-devel] [PATCH] configure: Work-around a bug in libiscsi 1.9.0 when used in gnu99 mode

["Daniel P. Berrangé" <berrange@redhat.com>]

On Mon, Jan 14, 2019 at 01:52:01PM +0000, Peter Maydell wrote:
> On Mon, 14 Jan 2019 at 13:47, Thomas Huth <thuth@redhat.com> wrote:
> >
> > The header "scsi-lowlevel.h" of libiscsi 1.9.0 contains some bad
> > "inline" prototype definitions which GCC refuses to compile in its
> > gnu99 mode:
> >
> > In file included from block/iscsi.c:52:0:
> > /usr/include/iscsi/scsi-lowlevel.h:810:13: error: inline function
> > ‘scsi_set_uint16’ declared but never defined [-Werror]
> >  inline void scsi_set_uint16(unsigned char *c, uint16_t val);
> >              ^
> > /usr/include/iscsi/scsi-lowlevel.h:809:13: error: inline function
> > ‘scsi_set_uint32’ declared but never defined [-Werror]
> >  inline void scsi_set_uint32(unsigned char *c, uint32_t val);
> >              ^
> >
> > This has been fixed by upstream libiscsi in version 1.10.0 (see
> > https://github.com/sahlberg/libiscsi/commit/7692027d6c11 ), but
> > since we still want to support 1.9.0 for CentOS 7 / RHEL7, we
> > have to work-around the issue by compiling with "-fgnu89-inline"
> > in this case instead.
> >
> > Suggested-by: Daniel P. Berrangé <berrange@redhat.com>
> > Signed-off-by: Thomas Huth <thuth@redhat.com>
> > ---
> >  configure | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/configure b/configure
> > index 2b9ba7d..aa80c17 100755
> > --- a/configure
> > +++ b/configure
> > @@ -4562,6 +4562,11 @@ if test "$libiscsi" != "no" ; then
> >      libiscsi="yes"
> >      libiscsi_cflags=$($pkg_config --cflags libiscsi)
> >      libiscsi_libs=$($pkg_config --libs libiscsi)
> > +    if $pkg_config --exact-version==1.9.0 libiscsi; then
> > +      # There are some bad inline declarations in scsi-lowlevel.h of
> > +      # libiscsi 1.9.0 which don't work in gnu99 mode without this:
> > +      libiscsi_cflags="-fgnu89-inline $libiscsi_cflags"
> > +    fi
> 
> Can we suppress the warnings with #pragma instead ?
> That would avoid compiling the .o file with different
> C semantics.

IIUC this is a built-in warning you can't disable, except by changing
the compilation mode to have gnu89 inline semantics :-(

I'd rather we just added  -Wno-error  to libiscsi_cflags instead of
changing compilation mode.

Regards,
Daniel
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