switch_expression_not_assignable

Type '{0}' of the switch expression isn't assignable to the type '{1}' of case expressions.

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.

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;
  }
}

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;
  }
}

Unless stated otherwise, the documentation on this site reflects Dart 3.8.0. Page last updated on 2025-05-08. View source or report an issue.