[PATCH] misra/eclair: set 'noreturn' attribute as safe during cast

[Dmytro Prokopchuk1 <dmytro_prokopchuk1@xxxxxxxx>]

ECLAIR reports a non-compliant cast due to the presence
of the 'noreturn' attribute in the callee function.
The issue occurs when casting a function pointer with
the 'noreturn' attribute (void noreturn (*)(void *))
to a general function pointer type (void (*)(void *)).

Configure ECLAIR to treat 'noreturn' attributes as safe
in this conversion.

Signed-off-by: Dmytro Prokopchuk <dmytro_prokopchuk1@xxxxxxxx>
---
Previous discussion thread:
https://patchew.org/Xen/181a03d5c7625d42c06cf9fa0cf48a9bc6825361.1753647875.git.dmytro._5Fprokopchuk1@xxxxxxxx/

Test CI pipeline:
https://gitlab.com/xen-project/people/dimaprkp4k/xen/-/pipelines/1953370442
---
 automation/eclair_analysis/ECLAIR/deviations.ecl | 7 +++++++
 docs/misra/deviations.rst                        | 6 ++++++
 docs/misra/rules.rst                             | 3 ++-
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/automation/eclair_analysis/ECLAIR/deviations.ecl 
b/automation/eclair_analysis/ECLAIR/deviations.ecl
index 483507e7b9..0e04681c4c 100644
--- a/automation/eclair_analysis/ECLAIR/deviations.ecl
+++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
@@ -367,6 +367,13 @@ constant expressions are required.\""
 }
 -doc_end
 
+-doc_begin="The conversion from 'void noreturn (*)(void *)' to 'void (*)(void 
*)' is safe
+because the semantics of the 'noreturn' attribute do not alter the calling 
convention or behavior of the resulting code."
+-config=MC3A2.R11.1,casts+={safe,
+  "kind(bitcast)&&to(type(pointer(inner(return(builtin(void))&&all_param(1, 
pointer(builtin(void)))))))&&from(expr(skip(!syntactic(),
+   ref(property(noreturn)))))"} 
+-doc_end
+
 -doc_begin="The conversion from a pointer to an incomplete type to unsigned 
long does not lose any information, provided that the target type has enough 
bits to store it."
 -config=MC3A2.R11.2,casts+={safe,
   "from(type(any()))
diff --git a/docs/misra/deviations.rst b/docs/misra/deviations.rst
index e78179fcb8..4e430bb17e 100644
--- a/docs/misra/deviations.rst
+++ b/docs/misra/deviations.rst
@@ -342,6 +342,12 @@ Deviations related to MISRA C:2012 Rules:
        semantics that do not lead to unexpected behaviour.
      - Tagged as `safe` for ECLAIR.
 
+   * - R11.1
+     - The conversion from 'void noreturn (*)(void *)' to 'void (*)(void *)'
+       is safe because the semantics of the 'noreturn' attribute do not alter
+       the calling convention or behavior of the resulting code.
+     - Tagged as `safe` for ECLAIR.
+
    * - R11.2
      - The conversion from a pointer to an incomplete type to unsigned long
        does not lose any information, provided that the target type has enough
diff --git a/docs/misra/rules.rst b/docs/misra/rules.rst
index 3e014a6298..82a26162a9 100644
--- a/docs/misra/rules.rst
+++ b/docs/misra/rules.rst
@@ -404,7 +404,8 @@ maintainers if you want to suggest a change.
        function and any other type
      - All conversions to integer types are permitted if the destination
        type has enough bits to hold the entire value. Conversions to
-       bool and void* are permitted.
+       bool and void* are permitted. Conversions from 'void noreturn (*)(void 
*)'
+       to 'void (*)(void *)' are permitted.
 
    * - `Rule 11.2 
<https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_11_02.c>`_
      - Required
-- 
2.43.0