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prefer-specific-cases-first

added in: 1.11.0
warning
🛠
Dart 3.0+
Pro+
preset: recommended

Warns when a more specific switch case is placed after a more general one.

This can lead to the more specific case to never match.

Example​

❌ Bad:

void fn(SomeClass param) {
  final value = switch (param) {
    Sub() => 1,
    Sub() when param.value.isEmpty => 2, // LINT: This case is more specific than one of the above and will never match. Try moving it higher.
    _ => 3,
  };

  switch (param) {
    case Sub():
      print(1);

    // LINT: This case is more specific than one of the above and will never match. Try moving it higher.
    case Sub() when param.value.isEmpty:
      print(2);

    case _:
      print(3);
  }
}

class SomeClass {
  final String value;

  const SomeClass(this.value);
}

class Sub extends SomeClass {
  const Sub(super.value);
}

✅ Good:

void fn(SomeClass param) {
  final value = switch (param) {
    Sub() when param.value.isEmpty => 2,
    Sub() => 1,
    _ => 3,
  };

  switch (param) {
    case Sub() when param.value.isEmpty:
      print(2);

    case Sub():
      print(1);

    case _:
      print(3);
  }
}

Additional Resources​