missing_enum_constant_in_switch

Missing case clause for '{0}'.

The analyzer produces this diagnostic when a switch statement for an enum doesn't include an option for one of the values in the enum.

Note that null is always a possible value for an enum and therefore also must be handled.

The following code produces this diagnostic because the enum value e2 isn't handled:

enum E { e1, e2 }
​
void f(E e) {
  switch (e) {
    case E.e1:
      break;
  }
}

If there's special handling for the missing values, then add a case clause for each of the missing values:

enum E { e1, e2 }
​
void f(E e) {
  switch (e) {
    case E.e1:
      break;
    case E.e2:
      break;
  }
}

If the missing values should be handled the same way, then add a default clause:

enum E { e1, e2 }
​
void f(E e) {
  switch (e) {
    case E.e1:
      break;
    default:
      break;
  }
}