Re: [PATCH] tools: libxc: do not redefine evtchn_port_or_error_t in xc_evtchn_compat.c

[Wei Liu <wei.liu2@citrix.com>]

On Thu, Feb 04, 2016 at 10:19:55AM +0000, Ian Campbell wrote:
> Adding Olaf, I forgot that Reported-by doesn't turn into a Cc.
> 
> On Thu, 2016-02-04 at 10:15 +0000, Ian Campbell wrote:
> > This file stradles the xenevtchn and libxc evtchn_compat worlds, and
> > hence ends up with two evtchn_port_or_error_t typedefs which older
> > gcc's (and the C standard) do not like.
> > 
> > Avoid this by gating the compat definition on a gate provided by the
> > compat implementation.
> > 
> > Note that this would still be broken by an application which does:
> >     #define XC_WANT_COMPAT_EVTCHN_API
> >     #include <xenevtchn.h>
> >     #include <xenctrl.h>
> > 
> > Which effectively means that an application must be ported over to
> > xenevtchn in one go rather than incrementally (e.g. if it uses
> > evtchn's for multiple purposes). Since the port is actually fairly
> > mechanical I hope this is acceptable.
> > 
> > Reported-by: Olaf Hering <olaf@aepfle.de>
> > Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
> > Cc: Andrew Cooper <andrew.cooper3@citrix.com>
> > ---
> > I'm not super happy about this approach, due to the caveat in the
> > second half of the commit message.
> > 
> > Other approaches:
> > 
> > rename the libxenevtchn type, e.g.  xenevtchn_port_or_error_t?
> 
> Thinking about this some more this might be the best approach. The type is
> not used by qemu-xen, it is used by qemu-xen-traditional but we can fix
> that in lockstep.
> 
> All of the in tree users are easy, of course.
> 
> Thoughts?
> 

+1 for this