avoid-duplicate-constant-values

v1.22.0

warning

configurable

pro+

Warns when a class or enum declaration has several constants with the same primitive values.

Duplicate enum constants are usually the result of a typo and a sign of a bug.

⚙️ Config

Set allowed (default is [-1, 0, 1]) to configure the list of allowed constants.

analysis_options.yaml

dart_code_metrics:
  rules:
    - avoid-duplicate-constant-values:
        allowed: [1, "value"]

Example

❌ Bad:

enum MyEnum {
  a('hi'),
  // LINT: Avoid duplicate constant values.
  //  Try changing this value or moving it out to a separate constant.
  b('hi'),
  c('another');

  final String value;

  const MyEnum(this.value);
}

class RuleType {
  final String value;

  const RuleType._(this.value);

  static const common = RuleType._('common');
  // LINT: Avoid duplicate constant values.
  //  Try changing this value or moving it out to a separate constant.
  static const flutter = RuleType._('common');
}

✅ Good:

enum MyEnum {
  a('hi'),
  b('hello'), // Correct, different value
  c('another');

  final String value;

  const MyEnum(this.value);
}

class RuleType {
  final String value;

  const RuleType._(this.value);

  static const common = RuleType._('common');
  static const flutter = RuleType._('flutter'); // Correct, different value
}

Additional Resources

• CWE-1041: Use of Redundant Code

Related Rules

• enum-constants-ordering