A6-4-1 What is the definition of a "case-clause"?

[cgpzs]

Hi!

Rule A6-4-1 says:

Rule A6-4-1 (required, implementation, automated)
A switch statement shall have at least two case-clauses, distinct from
the default label.


What is the definition of a "case-clause"? Is it a "case-clause label", or a "case-clause block of code"?

Our static analyzer is warning about this code:

Code:

void foo(int i)
{
  switch(i)
  {
    case 3:
    case 7:
    case 12:
    case 25:
      doSomething();
      break;

    default:
      doSomethingElse();
      break;
  }
}

It warns because there is only one case "block of code" (doSomething), and it expects that there are at least 2 (distinct from default case). It then wants us to rewrite the code in a much less readable way, like:

Code:

if (i == 3 || i == 7 || i == 12 || i == 25)
{  
  doSomething();
}
else
{
  doSomethingElse()
}

Is our static analyzer correct in warning A6-4-1 in the above code?

Please note: A6-4-1 inherits from HIC++ HIC++ v4.0 [9]: 6.1.4, which is more explicit than AUTOSAR, claiming that "at least two case labels" are needed. There's a big difference between "label" and "block".

Furthermore, consider the documentation from Perforce about HIC++ 6.1.4:

https://www.perforce.com/resources/qac/h...statements

There, they claim that the following code is compliant (while not being compliant in AUTOSAR):

Code:

// @@+ Compliant: 2 case labels distinct from the default label +@@
switch (i)
{
  case 0:
  case 1:
    doSomething ();
    break;
  default:
    doSomethingElse ();
    break;
}

Why should AUTOSAR change the meaning of the HIC++ rule?

Thanks!

[misra cpp]

Your static analyser is strictly correct in flagging a violation in your example. "case-clause” is the case label and associated code.

The rule as written was considering a switch with a single case-label and default. However, as your example illustrates, if you have multiple values to test, the switch statement is clearer than the if. This has been recognized and would be accepted as grounds for a deviation. Indeed, you may find that your static analyser has a flag that prevents it raising violations in code like your example.