Re: [PATCH v2 2/6] configure: avoid new clang 11+ warnings

[Daniele Buono]

Using an array of length 0 seems to be enough to avoid the warning
Will use that solution in v3.

Thanks,
Daniele

On 10/26/2020 11:12 AM, Paolo Bonzini wrote:
> On 26/10/20 16:03, Daniele Buono wrote:
> > Hi Paolo,
> > I reorganized UASStatus to put uas_iu at the end and it works fine.
> > Unfortunately, this uncovered another part of the code with a similar
> > issue (variable sized type not at the end of the struct), here:
> >
> > In file included from ../qemu-cfi-v3/target/s390x/diag.c:21:
> > ../qemu-cfi-v3/hw/s390x/ipl.h:161:23: error: field 'iplb' with variable
> > sized type 'IplParameterBlock' (aka 'union IplParameterBlock') not at
> > the end of a struct or class is a GNU extension
> > [-Werror,-Wgnu-variable-sized-type-not-at-end]
> >      IplParameterBlock iplb;
> >                        ^
> > ../qemu-cfi-v3/hw/s390x/ipl.h:162:23: error: field 'iplb_pv' with
> > variable sized type 'IplParameterBlock' (aka 'union IplParameterBlock')
> > not at the end of a struct or class is a GNU extension
> > [-Werror,-Wgnu-variable-sized-type-not-at-end]
> >      IplParameterBlock iplb_pv;
> >
> > My understanding is that each of these IplParameterBlock may contain
> > either a IPLBlockPV or a IplBlockFcp, which both end with a variable
> > sized field (an array).
> >
> > Adding maintainers of s390x to see if they have a suggested solution to
> > avoid disabling the warning.
>
> This one seems okay because the union constrains the size to 4K. If
> "[0]" is enough to shut up the compiler, I'd say do that.
>
> Paolo