unused_label

The label '{0}' isn't used.

The analyzer produces this diagnostic when a label that isn't used is found.

The following code produces this diagnostic because the label loop isn't referenced anywhere in the method:

void f(int limit) {
  loop: for (int i = 0; i < limit; i++) {
    print(i);
  }
}

If the label isn't needed, then remove it:

void f(int limit) {
  for (int i = 0; i < limit; i++) {
    print(i);
  }
}

If the label is needed, then use it:

void f(int limit) {
  loop: for (int i = 0; i < limit; i++) {
    print(i);
    if (i != 0) {
      break loop;
    }
  }
}