no_self_assignments

Details
Usage

Don’t assign a variable to itself.

This rule is available as of Dart 3.1.0-wip.

Details

DON’T assign a variable to itself. Usually this is a mistake.

BAD:

class C {
  int x;

  C(int x) {
    x = x;
  }
}

GOOD:

class C {
  int x;

  C(int x) : x = x;
}

GOOD:

class C {
  int x;

  C(int x) {
    this.x = x;
  }
}

BAD:

class C {
  int _x = 5;

  int get x => _x;

  set x(int x) {
    _x = x;
    _customUpdateLogic();
  }

  void _customUpdateLogic() {
    print('updated');
  }

  void example() {
    x = x;
  }
}

GOOD:

class C {
  int _x = 5;

  int get x => _x;

  set x(int x) {
    _x = x;
    _customUpdateLogic();
  }

  void _customUpdateLogic() {
    print('updated');
  }

  void example() {
    _customUpdateLogic();
  }
}

BAD:

class C {
  int x = 5;

  void update(C other) {
    this.x = this.x;
  }
}

GOOD:

class C {
  int x = 5;

  void update(C other) {
    this.x = other.x;
  }
}

Usage

To enable the no_self_assignments rule, add no_self_assignments under linter > rules in your analysis_options.yaml file:

linter:
  rules:
    - no_self_assignments