[XEN PATCH v2 1/2] automation/eclair: update configuration of Rule 20.7

[Federico Serafini <federico.serafini@xxxxxxxxxxx>]

MISRA C:2012 Rule 20.7 states that "Expressions resulting from the
expansion of macro parameters shall be enclosed in parentheses".
The rational of the rule is that if a macro argument expands to an
expression, there may be problems related to operator precedence, e.g.,

define M(A, B) A * B

M(1+1, 2+2) will expand to: 1+1 * 2+2

Update ECLAIR configuration to tag as 'safe' the expansions of macro
arguments surrounded tokens '{', '}' and ';', since in their presence
problems related to operator precedence can not occur.

Signed-off-by: Federico Serafini <federico.serafini@xxxxxxxxxxx>
---
Changes from v1:
- more details to justify the deviation;
- split modifications in two patches.
---
 automation/eclair_analysis/ECLAIR/deviations.ecl | 4 ++++
 docs/misra/deviations.rst                        | 5 +++++
 2 files changed, 9 insertions(+)

diff --git a/automation/eclair_analysis/ECLAIR/deviations.ecl 
b/automation/eclair_analysis/ECLAIR/deviations.ecl
index 9051f41602..e0d9426b7a 100644
--- a/automation/eclair_analysis/ECLAIR/deviations.ecl
+++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
@@ -581,6 +581,10 @@ of this macro do not lead to developer confusion, and can 
thus be deviated."
 -config=MC3R1.R20.7,reports+={safe, 
"any_area(any_loc(any_exp(macro(^count_args_$))))"}
 -doc_end
 
+-doc_begin="Problems related to operator precedence can not occur if the 
expansion of the macro argument is surrounded by tokens '{', '}' and ';'."
+-config=MC3R1.R20.7,expansion_context+={safe, "left_right(^[\\{;]$,^[;\\}]$)"}
+-doc_end
+
 -doc_begin="Uses of variadic macros that have one of their arguments defined as
 a macro and used within the body for both ordinary parameter expansion and as 
an
 operand to the # or ## operators have a behavior that is well-understood and
diff --git a/docs/misra/deviations.rst b/docs/misra/deviations.rst
index b66c271c4e..69f93a6a91 100644
--- a/docs/misra/deviations.rst
+++ b/docs/misra/deviations.rst
@@ -534,6 +534,11 @@ Deviations related to MISRA C:2012 Rules:
        refactoring it to add parentheses breaks its functionality.
      - Tagged as `safe` for ECLAIR.
 
+   * - R20.7
+     - Problems related to operator precedence can not occur if the expansion
+       of the macro argument is surrounded by tokens '{', '}' and ';'.
+     - Tagged as `safe` for ECLAIR.
+
    * - R20.12
      - Variadic macros that use token pasting often employ the gcc extension
        `ext_paste_comma`, as detailed in `C-language-toolchain.rst`, which is
-- 
2.34.1