[XEN PATCH v5] automation/eclair: extend existing deviations of MISRA C Rule 16.3

[Federico Serafini <federico.serafini@xxxxxxxxxxx>]

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

Tag Rule 16.3 as clean for arm.

Signed-off-by: Federico Serafini <federico.serafini@xxxxxxxxxxx>
---
Hi, v4 of this patch has been on hold due to discussion on whether or not
to consider switch clauses ending with ASSERT_UNREACHABLE() as safe;
I propose the patch again to continue the discussion and maybe reach an
agreement.
---
Changes from v4:
- rebase against staging.
---
Changes from v3:
- do not add the rule to the monitored set (it is already there).
---
Changes from v2:
- fixed grammar;
- reprhased deviations regarding do-while-false and ASSERT_UNREACHABLE().
---
 .../eclair_analysis/ECLAIR/deviations.ecl     | 28 +++++++++++++++----
 automation/eclair_analysis/ECLAIR/tagging.ecl |  2 +-
 docs/misra/deviations.rst                     | 28 +++++++++++++++++--
 3 files changed, 48 insertions(+), 10 deletions(-)

diff --git a/automation/eclair_analysis/ECLAIR/deviations.ecl 
b/automation/eclair_analysis/ECLAIR/deviations.ecl
index 1aa8277066..9051f41602 100644
--- a/automation/eclair_analysis/ECLAIR/deviations.ecl
+++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
@@ -461,14 +461,30 @@ 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
diff --git a/automation/eclair_analysis/ECLAIR/tagging.ecl 
b/automation/eclair_analysis/ECLAIR/tagging.ecl
index 4d0ac94848..b8448938e6 100644
--- a/automation/eclair_analysis/ECLAIR/tagging.ecl
+++ b/automation/eclair_analysis/ECLAIR/tagging.ecl
@@ -112,7 +112,7 @@ if(string_equal(target,"x86_64"),
 )
 
 if(string_equal(target,"arm64"),
-    
service_selector({"additional_clean_guidelines","MC3R1.R16.6||MC3R1.R2.1||MC3R1.R5.3||MC3R1.R7.3"})
+    
service_selector({"additional_clean_guidelines","MC3R1.R2.1||MC3R1.R5.3||MC3R1.R7.3||MC3R1.R16.3||MC3R1.R16.6"})
 )
 
 
-reports+={clean:added,"service(clean_guidelines_common||additional_clean_guidelines)"}
diff --git a/docs/misra/deviations.rst b/docs/misra/deviations.rst
index d51aa422b5..b66c271c4e 100644
--- a/docs/misra/deviations.rst
+++ b/docs/misra/deviations.rst
@@ -415,12 +415,34 @@ 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 statements.
+     - 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