Re: [Xen-devel] [PATCH for-4.6] xen/public: arm: Use __typeof__ rather than typeof

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Fri, 2015-10-23 at 15:31 +0100, Ian Campbell wrote:
> On Fri, 2015-10-23 at 08:16 -0600, Jan Beulich wrote:
> > > > > On 23.10.15 at 15:58, <julien.grall@xxxxxxxxxx> wrote:
> > > On 23/10/15 14:52, Jan Beulich wrote:
> > > > > > > On 23.10.15 at 15:30, <ian.campbell@xxxxxxxxxx> wrote:
> > > > > On Fri, 2015-10-23 at 14:13 +0100, Julien Grall wrote:
> > > > > > Hi,
> > > > > > 
> > > > > > On 04/10/15 20:24, Julien Grall wrote:
> > > > > > > The keyword typeof is not portable:
> > > > > > > 
> > > > > > > /usr/src/freebsd/sys/xen/hypervisor.h:93:2: error: implicit
> > > > > > > declaration
> > > > > > > of function 'typeof' is invalid in C99
> > > > > > > [-Werror,-Wimplicit-function-declaration]
> > > > > > 
> > > > > > Ping? Aside the fact that other bits of the header may not be
> > > > > > iso
> > > > > > compliant, I still think this patch is valid.
> > > > > 
> > > > > Yes, I agree.
> > > > > Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > > > > 
> > > > > Jan, after your earlier comments are you happy to go ahead with
> > > > > this for
> > > > > now and sort the other possible issues separately?
> > > > 
> > > > Well - it's an improvement, sure, so I'm not intending to block it
> > > > going in if no better way can be determined in its place right
> > > > away.
> > > > What makes me hesitant is that I'm not sure there indeed will be a
> > > > follow up to this any time soon.
> > > 
> > > TBH, having a script which check the validity of the headers is not
> > > in
> > > the top my todo list. Though it would be nice to have it.
> > 
> > No, the validating script is a nice-to-have, but nothing more. What
> > I was referring to was a patch to drop the use of this gcc extension.
> 
> Then I'm confused. This patch turns a typeof into a __typeof__. In <
> 56126D8702000078000A80AC@xxxxxxxxxxxxxxxxxxxxxxx> you said "typeof() is a
> gcc extension".
> 
> Are you now saying that __typeof__ also a gcc extension too?
> 
> I was under the impression that __typeof__ was standard (by some cxx at
> least) and your mail reinforced that (possibly wrong) impression.

Hrm, it seems I was indeed wrong here and __typeof__ is just an alternative
name for the gcc extension keyword which is not subject to -ansi.

Ian.

> 
> https://gcc.gnu.org/onlinedocs/gcc/Typeof.html also says that "If you are
> writing a header file that must work when included in ISO C programs,
> write
> __typeof__ instead of typeof", which also lead me to believe __typeof__
> was
> OK from this PoV.
> 
> Ian.

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel