avoid-misused-set-literals

added in: 1.21.0

Pro+

Warns when a set literal is used in a wrong place.

Example

❌ Bad:

void fn() {
  wrong(() => {1}); // LINT: Avoid misused set literals. Try removing the set literal around the expression.
  wrong(() async => {1}); // LINT: Avoid misused set literals. Try removing the set literal around the expression.
  wrongNamed(callback: () => {1}); // LINT: Avoid misused set literals. Try removing the set literal around the expression.
  
  final void Function() wrong = () => {1}; // LINT: Avoid misused set literals. Try removing the set literal around the expression.
}

void wrongNamed({required void Function() callback}) {}
void wrong(void Function() p) {}

void wrong() => {1}; // LINT: Avoid misused set literals. Try removing the set literal around the expression.

class _State<T> extends State<T> {
  String value;

  @override
  Widget build() {
    return MyWidget(
      // LINT: Avoid misused set literals. Try removing the set literal around the expression.
      onPressed: () => {
        setState(() {
          value = '2';
        })
      },
    );
  }
}

✅ Good:

void fn() {
  correct(() => 1); // Correct, no set literal
  correct(() async => 1);
  correctNamed(callback: () => 1);
  
  final void Function() correct = () => 1;
  // or
  final void Function() correct = () { 1; };
}

void correctNamed({required void Function() callback}) {}
void correct(void Function() p) {}

void correct() {
  print('');
};

class _State<T> extends State<T> {
  String value;

  @override
  Widget build() {
    return MyWidget(
      onPressed: () { // Correct, '=>' is removed
        setState(() {
          value = '2';
        });
      },
    );
  }
}

Example​

Example