avoid_unused_parameters

Warns about unused function, method, constructor or factory parameters.

Example:

BAD:

typedef MaxFun = int Function(int a, int b);
final MaxFun bad = (int a, int b) => 1; // LINT
final MaxFun testFun = (int a, int b) { // LINT
  return 4;
};
final optional = (int a, [int b = 0]) { // LINT
  return a;
};
void fun(String x) {} // LINT
void fun2(String x, String y) { // LINT
  print(y);
}

class TestClass {
  static void staticMethod(int a) {} // LINT
  void method(String s) {} // LINT

  TestClass([int a]); // LINT
  factory TestClass.named(int a) { // LINT
    return TestClass();
  }
}

GOOD:

typedef MaxFun = int Function(int a, int b);
final MaxFun good = (int a, int b) => a + b;
final MaxFun testFun = (int a, int b) {
  return a + b;
};
void fun(String _) {} // Replacing with underscores silences the warning
void fun2(String _, String y) {
  print(y);
}

class TestClass {
  static void staticMethod(int _) {} // OK
  void method(String _) {} // OK

  TestClass([int _]); // OK
  factory TestClass.named(int _) { // OK
    return TestClass();
  }
}

Allowed:

typedef Named = String Function({required String text});
final Named named = ({required text}) {
 return '';
};