On 19.08.2025 15:12, Dmytro Prokopchuk1 wrote:
> MISRA C Rule 2.1 states: "A project shall not contain unreachable code."
>
> The function 'PrintErrMesg()' is implemented to never return control to
> its caller. At the end of its execution, it calls 'blexit()', which, in
> turn, invokes '__builtin_unreachable()'. This makes the 'return false;'
> statement in 'read_file()' function unreachable.
I'm disappointed. In earlier review comments I pointed out that there are
two. Yet you say "the", without further disambiguation.
> --- a/automation/eclair_analysis/ECLAIR/deviations.ecl
> +++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
> @@ -41,6 +41,10 @@ not executable, and therefore it is safe for them to be
> unreachable."
>
> -call_properties+={"name(__builtin_unreachable)&&stmt(begin(any_exp(macro(name(ASSERT_UNREACHABLE)))))",
> {"noreturn(false)"}}
> -doc_end
>
> +-doc_begin="Unreachability caused by the call to the 'PrintErrMesg()'
> function is deliberate, as it terminates execution, ensuring no control flow
> continues past this point."
> +-config=MC3A2.R2.1,reports+={deliberate, "any_area(^.*PrintErrMesg.*$ &&
> any_loc(file(^xen/common/efi/boot\\.c$)))"}
> +-doc_end
I don't understand the description here, nor ...
> --- a/docs/misra/deviations.rst
> +++ b/docs/misra/deviations.rst
> @@ -97,6 +97,13 @@ Deviations related to MISRA C:2012 Rules:
> Xen expects developers to ensure code remains safe and reliable in
> builds,
> even when debug-only assertions like `ASSERT_UNREACHABLE() are
> removed.
>
> + * - R2.1
> + - Function `PrintErrMesg()` terminates execution (at the end it calls
> + `blexit()`, which, in turn, invokes `__builtin_unreachable()`),
> ensuring
> + no code beyond this point is ever reached. This guarantees that
> execution
> + won't incorrectly proceed or introduce unwanted behavior.
> + - Tagged as `deliberate` for ECLAIR.
.. the text here. PrintErrMesg() is noreturn. Why would anything need saying
about
it? Isn't the problem here solely with the tail of read_file(), while other uses
of PrintErrMesg() are okay?
Jan
