Update ECLAIR configuration to deviate more cases where an
unintentional fallthrough cannot happen.

Add Rule 16.3 to the monitored set and tag it as clean for arm.

Signed-off-by: Federico Serafini <federico.serafini@bugseng.com>
---
Changes from v2:
- fixed grammar;
- reprhased deviations regarding do-while-false and ASSERT_UNREACHABLE().
---
 .../eclair_analysis/ECLAIR/deviations.ecl     | 31 ++++++++++++++-----
 .../eclair_analysis/ECLAIR/monitored.ecl      |  1 +
 automation/eclair_analysis/ECLAIR/tagging.ecl |  2 +-
 docs/misra/deviations.rst                     | 28 +++++++++++++++--
 4 files changed, 50 insertions(+), 12 deletions(-)

diff --git a/automation/eclair_analysis/ECLAIR/deviations.ecl b/automation/eclair_analysis/ECLAIR/deviations.ecl
index 447c1e6661..3bdfc3a84d 100644
--- a/automation/eclair_analysis/ECLAIR/deviations.ecl
+++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
@@ -364,14 +364,30 @@ therefore it is deemed better to leave such files as is."
 -config=MC3R1.R16.2,reports+={deliberate, "any_area(any_loc(file(x86_emulate||x86_svm_emulate)))"}
 -doc_end
 
--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_begin="Statements that change the control flow (i.e., break, continue, goto, return) and calls to functions that do not return the control back are \"allowed terminal statements\"."
+-stmt_selector+={r16_3_allowed_terminal, "node(break_stmt||continue_stmt||goto_stmt||return_stmt)||call(property(noreturn))"}
+-config=MC3R1.R16.3,terminals+={safe, "r16_3_allowed_terminal"}
+-doc_end
+
+-doc_begin="An if-else statement having both branches ending with an allowed terminal statement is itself an allowed terminal statement."
+-stmt_selector+={r16_3_if, "node(if_stmt)&&(child(then,r16_3_allowed_terminal)||child(then,any_stmt(stmt,-1,r16_3_allowed_terminal)))"}
+-stmt_selector+={r16_3_else, "node(if_stmt)&&(child(else,r16_3_allowed_terminal)||child(else,any_stmt(stmt,-1,r16_3_allowed_terminal)))"}
+-stmt_selector+={r16_3_if_else, "r16_3_if&&r16_3_else"}
+-config=MC3R1.R16.3,terminals+={safe, "r16_3_if_else"}
+-doc_end
+
+-doc_begin="An if-else statement having an always true condition and the true branch ending with an allowed terminal statement is itself an allowed terminal statement."
+-stmt_selector+={r16_3_if_true, "r16_3_if&&child(cond,definitely_in(1..))"}
+-config=MC3R1.R16.3,terminals+={safe, "r16_3_if_true"}
+-doc_end
+
+-doc_begin="A switch clause ending with a statement expression which, in turn, ends with an allowed terminal statement is safe."
+-config=MC3R1.R16.3,terminals+={safe, "node(stmt_expr)&&child(stmt,node(compound_stmt)&&any_stmt(stmt,-1,r16_3_allowed_terminal||r16_3_if_else||r16_3_if_true))"}
 -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_begin="A switch clause ending with a do-while-false the body of which, in turn, ends with an allowed terminal statement is safe.
+An exception to that is the macro ASSERT_UNREACHABLE() which is effective in debug build only: a switch clause ending with ASSERT_UNREACHABLE() is not considered safe."
+-config=MC3R1.R16.3,terminals+={safe, "!macro(name(ASSERT_UNREACHABLE))&&node(do_stmt)&&child(cond,definitely_in(0))&&child(body,any_stmt(stmt,-1,r16_3_allowed_terminal||r16_3_if_else||r16_3_if_true))"}
 -doc_end
 
 -doc_begin="Switch clauses ending with pseudo-keyword \"fallthrough\" are
@@ -383,8 +399,7 @@ 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."
+-doc_begin="Switch clauses ending with an explicit comment indicating the fallthrough intention are safe."
 -config=MC3R1.R16.3,reports+={safe, "any_area(end_loc(any_exp(text(^(?s).*/\\* [fF]all ?through.? \\*/.*$,0..1))))"}
 -doc_end
 
diff --git a/automation/eclair_analysis/ECLAIR/monitored.ecl b/automation/eclair_analysis/ECLAIR/monitored.ecl
index 4daecb0c83..45a60074f9 100644
--- a/automation/eclair_analysis/ECLAIR/monitored.ecl
+++ b/automation/eclair_analysis/ECLAIR/monitored.ecl
@@ -22,6 +22,7 @@
 -enable=MC3R1.R14.1
 -enable=MC3R1.R14.4
 -enable=MC3R1.R16.2
+-enable=MC3R1.R16.3
 -enable=MC3R1.R16.6
 -enable=MC3R1.R16.7
 -enable=MC3R1.R17.1
diff --git a/automation/eclair_analysis/ECLAIR/tagging.ecl b/automation/eclair_analysis/ECLAIR/tagging.ecl
index a354ff322e..07de2e7b65 100644
--- a/automation/eclair_analysis/ECLAIR/tagging.ecl
+++ b/automation/eclair_analysis/ECLAIR/tagging.ecl
@@ -105,7 +105,7 @@ if(string_equal(target,"x86_64"),
 )
 
 if(string_equal(target,"arm64"),
-    service_selector({"additional_clean_guidelines","MC3R1.R14.4||MC3R1.R16.6||MC3R1.R20.12||MC3R1.R2.1||MC3R1.R5.3||MC3R1.R7.2||MC3R1.R7.3||MC3R1.R8.6||MC3R1.R9.3"})
+    service_selector({"additional_clean_guidelines","MC3R1.R14.4||MC3R1.R16.3||MC3R1.R16.6||MC3R1.R20.12||MC3R1.R2.1||MC3R1.R5.3||MC3R1.R7.2||MC3R1.R7.3||MC3R1.R8.6||MC3R1.R9.3"})
 )
 
 -reports+={clean:added,"service(clean_guidelines_common||additional_clean_guidelines)"}
diff --git a/docs/misra/deviations.rst b/docs/misra/deviations.rst
index 36959aa44a..41cdfbe5f5 100644
--- a/docs/misra/deviations.rst
+++ b/docs/misra/deviations.rst
@@ -309,12 +309,34 @@ Deviations related to MISRA C:2012 Rules:
      - Tagged as `deliberate` for ECLAIR.
 
    * - R16.3
-     - Switch clauses ending with continue, goto, return statements are safe.
+     - Statements that change the control flow (i.e., break, continue, goto,
+       return) and calls to functions that do not return the control back are
+       \"allowed terminal statements\".
      - 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.
+     - An if-else statement having both branches ending with one of the allowed
+       terminal statemets is itself an allowed terminal statement.
+     - Tagged as `safe` for ECLAIR.
+
+   * - R16.3
+     - An if-else statement having an always true condition and the true
+       branch ending with an allowed terminal statement is itself an allowed
+       terminal statement.
+     - Tagged as `safe` for ECLAIR.
+
+   * - R16.3
+     - A switch clause ending with a statement expression which, in turn, ends
+       with an allowed terminal statement (e.g., the expansion of
+       generate_exception()) is safe.
+     - Tagged as `safe` for ECLAIR.
+
+   * - R16.3
+     - A switch clause ending with a do-while-false the body of which, in turn,
+       ends with an allowed terminal statement (e.g., PARSE_ERR_RET()) is safe.
+       An exception to that is the macro ASSERT_UNREACHABLE() which is
+       effective in debug build only: a switch clause ending with
+       ASSERT_UNREACHABLE() is not considered safe.
      - Tagged as `safe` for ECLAIR.
 
    * - R16.3
-- 
2.34.1

On Fri, 14 Jun 2024, Federico Serafini wrote:
> Update ECLAIR configuration to deviate more cases where an
> unintentional fallthrough cannot happen.
> 
> Add Rule 16.3 to the monitored set and tag it as clean for arm.
> 
> Signed-off-by: Federico Serafini <federico.serafini@bugseng.com>

Acked-by: Stefano Stabellini <sstabellini@kernel.org>

On Wed, 19 Jun 2024, Stefano Stabellini wrote:
> On Fri, 14 Jun 2024, Federico Serafini wrote:
> > Update ECLAIR configuration to deviate more cases where an
> > unintentional fallthrough cannot happen.
> > 
> > Add Rule 16.3 to the monitored set and tag it as clean for arm.
> > 
> > Signed-off-by: Federico Serafini <federico.serafini@bugseng.com>
> 
> Acked-by: Stefano Stabellini <sstabellini@kernel.org>

Hi Oleksii,

I would like to ask for a release-ack as this patch only increases
deviations, hence only affecting the static analysis jobs, for a rule
that is non-blocking

On 25/06/24 02:38, Stefano Stabellini wrote:
> On Wed, 19 Jun 2024, Stefano Stabellini wrote:
>> On Fri, 14 Jun 2024, Federico Serafini wrote:
>>> Update ECLAIR configuration to deviate more cases where an
>>> unintentional fallthrough cannot happen.
>>>
>>> Add Rule 16.3 to the monitored set and tag it as clean for arm.
>>>
>>> Signed-off-by: Federico Serafini <federico.serafini@bugseng.com>
>>
>> Acked-by: Stefano Stabellini <sstabellini@kernel.org>
> 
> Hi Oleksii,
> 
> I would like to ask for a release-ack as this patch only increases
> deviations, hence only affecting the static analysis jobs, for a rule
> that is non-blocking

A committed patch already added Rule 16.3 to the monitored set:
I will send a v4 rebasing against the current staging branch
with Oleksii in CC.

-- 
Federico Serafini, M.Sc.

Software Engineer, BUGSENG (http://bugseng.com)