Re: [Qemu-devel] Hacks for building on gcc 7 / Fedora 26

[Richard Henderson <rth@twiddle.net>]

On 07/17/2017 03:48 AM, Eric Blake wrote:
> On 07/17/2017 08:42 AM, Eric Blake wrote:
>> On 07/13/2017 08:07 AM, Philippe Mathieu-Daudé wrote:
>>> On 04/07/2017 04:21 PM, Philippe Mathieu-Daudé wrote:
>>>> Hi Dave,
>>>>
>>>> On 04/07/2017 11:38 AM, Dr. David Alan Gilbert wrote:
>>>>> Hi,
>>>>>     Fedora 26 has gcc 7.0.1 which has the normal compliment
>>>>> of new fussy warnings; so far I've posted :
>>>>>
>>>>> tests/check-qdict: Fix missing brackets
>>>>> slirp/smb: Replace constant strings by glib string
>>>>>
>>>>> that fix one actual mistake and work around something it's being
>>>>> fussy over.
>>>>>
>>>>> But I've also got a pile of hacks, attached below that I'm
>>>>> not too sure what I'll do with them yet, but they're attached
>>>
>>> ping ... What do we do with them?
>>
>> Well, now that I've upgraded to the just-released Fedora 26, it is now
>> mainline gcc and affecting my builds.  So we should really try and find
>> patches that silence the warnings (although it counts as bug fixes, so
>> it won't hurt if it doesn't make tomorrow's freeze deadline).
> 
> FWIW, most of these have been fixed in the meantime; the only remaining
> hack I had to add was:
> 
> diff --git i/hw/usb/bus.c w/hw/usb/bus.c
> index 5939b273b9..bce011058b 100644
> --- i/hw/usb/bus.c
> +++ w/hw/usb/bus.c
> @@ -407,8 +407,9 @@ void usb_register_companion(const char *masterbus,
> USBPort *ports[],
>   void usb_port_location(USBPort *downstream, USBPort *upstream, int portnr)
>   {
>       if (upstream) {
> -        snprintf(downstream->path, sizeof(downstream->path), "%s.%d",
> -                 upstream->path, portnr);
> +        int l = snprintf(downstream->path, sizeof(downstream->path),
> "%s.%d",
> +                         upstream->path, portnr);
> +        assert(l < sizeof(downstream->path));

Do you really need an assert there, or will

	(void)l; /* "used" */

work as well?  You didn't mention what the reported error is, so I'm guessing.


r~