V2542. MISRA. Function with a non-void return type should return a value from all exit paths.

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

The analyzer has detected a function with a non-void return type which doesn't return a value on all the paths of execution. According to the C/C++ standard, this can lead to undefined behavior.

Let's consider an example in which an undefined value is returned only occasionally:

BOOL IsInterestingString(char *s)
{
  if (s == NULL)
    return FALSE;
  if (strlen(s) < 4)
    return;
  return (s[0] == '#') ? TRUE : FALSE;
}

There is a typo in the code. If a string length is less than 4 characters, the function will return an undefined value. Correct variant:

BOOL IsInterestingString(char *s)
{
  if (s == NULL)
    return FALSE;
  if (strlen(s) < 4)
    return FALSE;
  return (s[0] == '#') ? TRUE : FALSE;
}

Note. The analyzer tries to identify the cases when the absence of the return value is not an error. Here's a code example, which will be considered safe:

int Foo()
{
  ...
  exit(10);
}

This diagnostic is classified as: