Re: [Qemu-devel] [PATCH] build: Work around SIZE_MAX bug in OSX headers

[Eric Blake <eblake@redhat.com>]

[-- Attachment #1: Type: text/plain, Size: 1781 bytes --]

On 07/12/2016 01:35 PM, Peter Maydell wrote:

> I tested this patch with a compile on OSX, and it does compile
> without warnings or errors. (NB: haven't tested that it
> fixes the warning that was being complained about in the
> other patchset.)

Ultimately, the combination of this patch plus the block patchset in
question is where we prove if it makes a positive difference, so if you
do have a chance to test it on OSX, that would be nice.  And that's true
whether we keep this version of the patch (with #if __APPLE__) or do a
second version based on a witness set at configure time, because the
interaction you're testing is if the replacement #define SIZE_MAX
silences the warning about printf(%zd).

> 
> I don't have a very strong opinion about whether it's the
> best fix, but a couple of thoughts:
>  * my inclination is to prefer not to override system
>    headers except where we've checked and know they're broken
>    (ie in a future world where Apple get their headers right
>    I'd rather we automatically ended up using their version
>    rather than ours)

Indeed, a configure-based solution would avoid checkpatch.pl griping
about adding an #if __APPLE__.

And since glibc has the same bug with SSIZE_MAX, a configure-based
solution would be easier to copy-and-paste if we needed to work around
that too (then again, we don't have any use of SSIZE_MAX at the moment).

>  * we don't have any #if ...SIZE_MAX, but we do have some
>    for other kinds of _MAX constant.

I'll wait a bit longer to see if any other opinions surface, but sounds
like I'll probably be doing a v2 and trying for a configure solution.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 604 bytes --]