[XEN PATCH v3] automation/eclair: add deviations for MISRA C:2012 Rule 16.3

[Federico Serafini <federico.serafini@xxxxxxxxxxx>]

MISRA C:2012 Rule 16.3 states that an unconditional break statement
shall terminate every switch-clause.

Update ECLAIR configuration to take into account:
  - continue, goto, return statements;
  - functions with attribute noreturn;
  - pseudo-keyword fallthrough;
  - macro BUG();
  - comments.

Update docs/misra/deviations.rst accordingly.

Signed-off-by: Federico Serafini <federico.serafini@xxxxxxxxxxx>
---
Changes in v3:
  - added bullet point for pseudo-keyword fallthrough;
  - mentioned noreturn attribute;
  - fixed typo.
---
Changes in v2:
  - applied suggestions coming from
    https://lists.xenproject.org/archives/html/xen-devel/2023-12/msg00957.html
---
 .../eclair_analysis/ECLAIR/deviations.ecl     | 28 ++++++++++++++++
 docs/misra/deviations.rst                     | 32 +++++++++++++++++++
 2 files changed, 60 insertions(+)

diff --git a/automation/eclair_analysis/ECLAIR/deviations.ecl 
b/automation/eclair_analysis/ECLAIR/deviations.ecl
index 683f2bbfe8..0e8152f9c3 100644
--- a/automation/eclair_analysis/ECLAIR/deviations.ecl
+++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
@@ -327,6 +327,34 @@ therefore have the same behavior of a boolean"
 -config=MC3R1.R14.4,etypes+={deliberate, 
"stmt(child(cond,child(expr,ref(^<?domain>?::is_dying$))))","src_type(enum)"}
 -doc_end
 
+#
+# Series 16.
+#
+
+-doc_begin="Switch clauses ending with continue, goto, return statements are
+safe."
+-config=MC3R1.R16.3,terminals+={safe, 
"node(continue_stmt||goto_stmt||return_stmt)"}
+-doc_end
+
+-doc_begin="Switch clauses ending with a call to a function that does not give
+the control back (i.e., a function with attribute noreturn) are safe."
+-config=MC3R1.R16.3,terminals+={safe, "call(property(noreturn))"}
+-doc_end
+
+-doc_begin="Switch clauses ending with pseudo-keyword \"fallthrough\" are
+safe."
+-config=MC3R1.R16.3,reports+={safe, 
"any_area(end_loc(any_exp(text(/fallthrough;/))))"}
+-doc_end
+
+-doc_begin="Switch clauses ending with failure method \"BUG()\" are safe."
+-config=MC3R1.R16.3,reports+={safe, 
"any_area(end_loc(any_exp(text(/BUG\\(\\);/))))"}
+-doc_end
+
+-doc_begin="Switch clauses not ending with the break statement are safe if an
+explicit comment indicating the fallthrough intention is present."
+-config=MC3R1.R16.3,reports+={safe, "any_area(end_loc(any_exp(text(^(?s).*/\\* 
[fF]all ?through.? \\*/.*$,0..1))))"}
+-doc_end
+
 #
 # Series 20.
 #
diff --git a/docs/misra/deviations.rst b/docs/misra/deviations.rst
index eda3c8100c..0131d72959 100644
--- a/docs/misra/deviations.rst
+++ b/docs/misra/deviations.rst
@@ -276,6 +276,38 @@ Deviations related to MISRA C:2012 Rules:
        therefore have the same behavior of a boolean.
      - Project-wide deviation; tagged as `deliberate` for ECLAIR.
 
+   * - R16.3
+     - Switch clauses ending with continue, goto, return statements are safe.
+     - Tagged as `safe` for ECLAIR.
+
+   * - R16.3
+     - Switch clauses ending with a call to a function that does not give
+       the control back (i.e., a function with attribute noreturn) are safe.
+     - Tagged as `safe` for ECLAIR.
+
+   * - R16.3
+     - Switch clauses ending with pseudo-keyword \"fallthrough\" are safe.
+     - Tagged as `safe` for ECLAIR.
+
+   * - R16.3
+     - Switch clauses ending with failure method \"BUG()\" are safe.
+     - Tagged as `safe` for ECLAIR.
+
+   * - R16.3
+     - Existing switch clauses not ending with the break statement are safe if
+       an explicit comment indicating the fallthrough intention is present.
+       However, the use of such comments in new code is deprecated:
+       the pseudo-keyword "fallthrough" shall be used.
+     - Tagged as `safe` for ECLAIR. The accepted comments are:
+         - /\* fall through \*/
+         - /\* fall through. \*/
+         - /\* fallthrough \*/
+         - /\* fallthrough. \*/
+         - /\* Fall through \*/
+         - /\* Fall through. \*/
+         - /\* Fallthrough \*/
+         - /\* Fallthrough. \*/
+
    * - R20.7
      - Code violating Rule 20.7 is safe when macro parameters are used:
        (1) as function arguments;
-- 
2.34.1