Re: [XEN PATCH v2 1/3] EFI: address a violation of MISRA C Rule 13.6

[Jan Beulich <jbeulich@xxxxxxxx>]

On 30.09.2024 14:49, Federico Serafini wrote:
> guest_handle_ok()'s expansion contains a sizeof() involving its
> first argument which is guest_handle_cast().
> The expansion of the latter, in turn, contains a variable
> initialization.
> 
> Since MISRA considers the initialization (even of a local variable)
> a side effect, the chain of expansions mentioned above violates
> MISRA C:2012 Rule 13.6 (The operand of the `sizeof' operator shall not
> contain any expression which has potential side effect).

I'm afraid I need to ask for clarification of terminology and alike here.
While the Misra doc has a section on Persistent Side Effects in its
Glossary appendix, what constitutes a side effect from its pov isn't
really spelled out anywhere. Which in turn raises the question whether it
is indeed Misra (and not just Eclair) which deems initialization a side
effect. This is even more so relevant as 13.6 talks of only expressions,
yet initializers fall under declarations (in turn involving an expression
on the rhs of the equal sign).

All the same of course affects patch 2 then, too.

Jan