Re: [XEN PATCH 7/7] x86/xstate: move BUILD_BUG_ON to address MISRA C:2012 Rule 2.1

[Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>]

On 2023-12-12 11:07, Jan Beulich wrote:
> On 12.12.2023 11:04, Jan Beulich wrote:
> > On 11.12.2023 11:30, Nicola Vetrini wrote:
> > > The string literal inside the expansion of BUILD_BUG_ON is considered
> > > unreachable code; however, such statement can be moved earlier
> > > with no functional change.
> > First: Why is this deemed dead code in its present position, but okay 
> > when
> > moved? Second: While moving is indeed no functional change (really
> > BUILD_BUG_ON() can be moved about anywhere, for not producing any code 
> > in
> > the final binary), it removes the connection between it and the 
> > respective
> > asm() (where %z would have been nice to use).
> Oh, and third: Which string literal? I expect you're not building with
> an ancient compiler, so it got to be
>
> #define BUILD_BUG_ON(cond) ({ _Static_assert(!(cond), "!(" #cond ")"); 
> })
> which you see in use. Yet that string literal isn't "code" or "data", 
> but
> an argument to _Static_assert(). Is Eclair perhaps not properly aware 
> of
> _Static_assert()?
>
> Jan
On further inspection, this should have fallen into the deviation for 
pure decls. This patch can be dropped, we'll adjust this inside ECLAIR.
--
Nicola Vetrini, BSc
Software Engineer, BUGSENG srl (https://bugseng.com)