automation/eclair: update configuration of Rule 20.7

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

diff --git a/automation/eclair_analysis/ECLAIR/deviations.ecl b/automation/eclair_analysis/ECLAIR/deviations.ecl
index 9c3ebc9cc7c470bb0cc3b3234dba7f277c36e978..6679caf3dacb9fa94ab4af6fc2f2f71513c00c75 100644 (file)
--- a/automation/eclair_analysis/ECLAIR/deviations.ecl
+++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
@@ -598,6 +598,10 @@ use of this macro, it is deemed ok to deviate them."
 -config=MC3R1.R20.7,reports+={deliberate, "any_area(any_loc(any_exp(macro(^(COMPILE_CHECK|RUNTIME_CHECK)$))))"}
 -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 247e69e7f1ef1dc2171bc3404297ac6dd90a8630..15a993d0500a5745c85ca1653250b5a165d49f8f 100644 (file)
--- a/docs/misra/deviations.rst
+++ b/docs/misra/deviations.rst
@@ -552,6 +552,11 @@ Deviations related to MISRA C:2012 Rules:
        usage scope, omitting parentheses is deemed unlikely to cause issues.
      - Tagged as `deliberate` 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