MISRA Violation 12.5 when using && and || in if-statement-CodePudding

I'm working on a project where we are appling MISRA 2004.

On most of the violations I got the reason, but one I don't understand:

Its in the if-statement with && and || operations.

Example:

uint8 getValue()
{
   // Some algorithm, simplified with return 1
   uint8 someValue = 1u;
   return someValue;
}
int main(int argc, char *argv[]) {
    uint8 currentState = 0u;
    uint8 var_a = getValue();
    uint8 var_b = getValue();
    uint8 var_c = getValue();
    uint8 var_d = getValue();

    const uint8 const_a = 1u;
    const uint8 const_b = 2u;
    const uint8 const_c1 = 3u;
    const uint8 const_c2 = 30u;
    const uint8 const_d = 4u;

    if ((var_a == const_a) && (var_b == const_b) && ((var_c == const_c1) || (var_c == const_c2)) && (var_d == const_d))
    {
        currentState = 1;
    } else 
    {
        currentState = 2;
    }
}

This gives me twice the MISRA violation to rule 12.5 non-primary expression used with logical operator. Both are in the line with the IF-Statement

I don't see a problem with this if-statement, despite its a bit long.

Does anybody know, whats wrong here and how to solve that violation?

Edit: I adjusted the example a bit. I also noticed, that I get only one error if I simplify the if statement to:

if ((var_a == const_a) && ((var_c == const_c1) || (var_c == const_c2)) && (var_d == const_d))

And no violation if its changed to:

if ((var_a == const_a) && ((var_c == const_c1) || (var_c == const_c2)))

CodePudding user response：

This appears to be a false positive by your static analyser. Your code is compliant.

The rationale for MISRA C:2004 12.5 (and the equivalent rules in the 2012 version) is to avoid situations where operator precedence might not be obvious. Overall MISRA insists that sub-expressions involving binary operators ("complex expressions") should always have parenthesis.

In case of the boolean && and || operators specifically, the rule 12.5 allows chaining multiple of them in the same expression, but not mixing && and || in the same expression without parenthesis, since they have different precedence.

Had you written && (var_c == const_c1) || (var_c == const_c2) && then the code would be non-conforming. You didn't however, and you did also put parenthesis around the inner sub-expressions.