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V2506. MISRA. A function should have a …


V2506. MISRA. A function should have a single point of exit at the end.

This diagnostic rule is based on the software development guidelines developed by MISRA (Motor Industry Software Reliability Association).

A function should have only one 'return' statement, which must come after all the other statements in the function's body. Multiple 'return' statements could obscure the code and make it harder to maintain.

Here is an example of code triggering this warning.

obj foo (....)
{
  ....
  if (condition) {
    return a;
  }
  ....
  if (other_condition) {
    return b;
  }
  ....
}

The fixed version of the function has only one point of exit at the end of its body:

obj foo (....)
{
  ....
  if (condition) {
    result = a;
  } else {
    ....
    if (other_condition) {
      result = b;
    }
  }
  ....
  return result;
}

This code will also be easier to maintain if you need to add some new features, such as caching of the return value, since you will have to add the new code only in once place:

obj foo (....)
{
  ....
  return cache(result);
}

This diagnostic is classified as:

  • MISRA-C-15.5
  • MISRA-CPP-6.6.5