Re: [Qemu-devel] [PATCH] io: fix build on FreeBSD

[Daniel P. Berrange]

On Thu, Feb 25, 2016 at 09:37:18AM -0700, Eric Blake wrote:
> On 02/25/2016 09:32 AM, Daniel P. Berrange wrote:
> 
> >>> +        if (
> >>> +#ifdef EAI_ADDRFAMILY
> >>> +            gaierr == EAI_ADDRFAMILY ||
> >>> +#endif
> >>>              gaierr == EAI_FAMILY ||
> >>
> >> I'm not the biggest-fan of mid-expression #ifdefs. Can we rewrite this
> >> to look more like:
> >>
> >> #ifndef EAI_ADDRFAMILY
> >> #define EAI_ADDRFAMILY EAI_FAMILY
> >> #endif
> >>
> >> and leave the conditional expression unchanged?
> > 
> > I think that'll cause gcc  6 to whine about you checking the same
> > value twice in the conditional, like how it complains that EWOULDBLOCK
> > and EAGAIN are the same.
> 
> Oh, right. That's annoying.  What about:
> 
> #ifndef EAI_ADDRFAMILY
> #define EAI_ADDRFAMILY 0
> #endif
> 
> if ((EAI_ADDRFAMILY && gaierr == EAIADDRFAMILY) ||
>     gaierr == EAI_FAMILY...
> 
> to shut up gcc 6, while still hoisting the preprocessor logic outside of
> the expression?

To be honest, I think the preprocessor check inside the expression isn't
a big deal and clearer than playing games like this.


Regards,
Daniel
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