V6002. The switch statement does not cover all values of the enum.


The analyzer has detected a 'switch' statement where selection is done for a variable of the enum type, and some of the enumeration elements are missing in the 'switch' statement. This may indicate an error.

Consider this example:

enum Fruit { APPLE, ORANGE, BANANA, PEAR, PEACH, PINEAPPLE }
int SomeMethod(Fruit fruit)
{
      int res = 0;
      switch (fruit)
      {
        case APPLE:
          res = calculate(10); break;
        case BANANA:
          res = calculate(20); break;
        case PEAR:
          res = calculate(30); break;
        case PINEAPPLE:
          res = calculate(40); break;
      }
      // code
      return res;
}

The 'Fruit' enumeration in this code contains 5 named constants, while the 'switch' statement, selecting among the values of this enumeration, only selects among 4 of them. This is very likely a mistake.

It may be that a programmer added a new constant during refactoring but forgot to add it into the list of cases in the 'switch' statement, or simply skipped it by mistake, as it sometimes happens with large enumerations. This results in incorrect processing of the missing value.

The correct version of this code should look like this:

int SomeMethod(Fruit fruit)
{
      int res = 0;
      switch (fruit)
      {
        case APPLE:
          res = calculate(10); break;
        case BANANA:
          res = calculate(20); break;
        case PEAR:
          res = calculate(30); break;
        case PINEAPPLE:
          res = calculate(40); break;
        case ORANGE:
          res = calculate(50); break;
      }
      // code
      return res;
}

The analyzer doesn't output the warning every time there are missing enumeration elements in the 'switch' statement; otherwise, there would be too many false positives. There are a number of empirical exceptions from this rule, the main of which are the following:

  • A default-branch is present;
  • The missing constant's name includes the words "None", "Unknown", and the like.
  • The missing constant is the very last in the enumeration and its name includes the words "end", "num", "count", and the like.
  • The enumeration consists of only 1 or 2 constants;
  • And so on.

Bugs Found

Checked Projects
367
Collected Errors
13 552