Re: [PATCH v2] xfs: Silence bounds checking compiler warning

From: Al Viro
Date: Thu Jun 23 2011 - 13:55:45 EST

On Thu, Jun 23, 2011 at 10:27:26AM -0700, Andi Kleen wrote:
> Maarten Lankhorst <m.b.lankhorst@xxxxxxxxx> writes:
> > gcc with -Warray-bounds generates a false positive on this
> > since xfs defines the struct with u8 name[1]; to be able to
> > add a tag at the end.
> A better way would be to define it as name[0]. Then the compiler
> would know it's a VLA. You may need to check noone relies on
> the one byte though.

... and even better is to write in real C and have u8 name[]; in the
end of your structure. That's the standard C99 for this kind of thing
(see, p16). Zero-sized array is a gccism predating standard
flexible array members and since the standard syntax is accepted by
any gcc version that might be recent enough to build the kernel...
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