Skip to main content

avoid-shadowing

added in: 1.2.0
warning
⚙️
Pro+
preset: recommended

Warns when a declaration name shadows another declaration with the same name in the current scope.

Shadowing an existing variable / parameter / field can lead to unexpected results, especially if the types of both declaration (shadowed and the new one) match.

⚙️ Config​

Set ignore-static (default is false) to exclude static fields from the name scope.

Set ignore-fields (default is false) to exclude fields from the name scope.

Set ignore-parameters (default is false) to exclude parameters from the name scope.

Set ignored-names (default is empty) to ignore specific names (example).

analysis_options.yaml
dart_code_metrics:
  rules:
    - avoid-shadowing:
        ignore-static: false
        ignore-fields: false
        ignore-parameters: false
        ignored-names:
          - some
          - name

Example​

❌ Bad:

class SomeClass {
  final String content;

  ...

  void method() {
    // LINT: Identifier with the same name is already declared in the outer scope. Try renaming this identifier.
    final content = ...;
  }

  // LINT: Identifier with the same name is already declared in the outer scope. Try renaming this identifier.
  void anotherMethod(String content) {
    ...
  }

  void records() {
    final declarations = <(int, String)>{};

    var length = 0;

    // LINT: Identifier with the same name is already declared in the outer scope. Try renaming this identifier.
    if (declarations case Set(:final length)) {
      ...
    }
    
    // LINT: Identifier with the same name is already declared in the outer scope. Try renaming this identifier.
    final Set(length: final length) = declarations;
  }
}

✅ Good:

class SomeClass {
  final String content;

  ...

  void method() {
    final localContent = ...;
  }

  void anotherMethod(String contentParam) {
    ...
  }

  void records() {
    final declarations = <(int, String)>{};

    var length = 0;

    if (declarations case Set(length: final someLength)) {
      ...
    }

    final Set(length: final someLength) = declarations;
  }
}

Example with "ignored-names"​

Config
analysis_options.yaml
dart_code_metrics:
  rules:
    - avoid-shadowing:
        ignored-names:
          - content

✅ Good:

class SomeClass {
  final String content;

  ...

  void method() {
    final content = ...; // Correct, 'content' is ignored
  }

  // Correct, 'content' is ignored
  void anotherMethod(String content) {
    ...
  }
}