Incompatible types in switch statementDRT-W1639

The analyzer produces this diagnostic when the type of the expression in a switch statement isn't assignable to the type of the expressions in the case clauses.

Example

The following code produces this diagnostic because the type of s (String) isn't assignable to the type of 0 (int):

void f(String s) {
  switch (s) {
    case 0:
      break;
  }
}

Common fixes

If the type of the case expressions is correct, then change the expression in the switch statement to have the correct type:

void f(String s) {
  switch (int.parse(s)) {
    case 0:
      break;
  }
}

If the type of the switch expression is correct, then change the case expressions to have the correct type:

void f(String s) {
  switch (s) {
    case '0':
      break;
  }
}