unnecessary_no_such_method

Unnecessary 'noSuchMethod' declaration.

The analyzer produces this diagnostic when there's a declaration of noSuchMethod, the only thing the declaration does is invoke the overridden declaration, and the overridden declaration isn't the declaration in Object.

Overriding the implementation of Object's noSuchMethod (no matter what the implementation does) signals to the analyzer that it shouldn't flag any inherited abstract methods that aren't implemented in that class. This works even if the overriding implementation is inherited from a superclass, so there's no value to declare it again in a subclass.

The following code produces this diagnostic because the declaration of noSuchMethod in A makes the declaration of noSuchMethod in B unnecessary:

class A {
  @override
  dynamic noSuchMethod(x) => super.noSuchMethod(x);
}
class B extends A {
  @override
  dynamic noSuchMethod(y) {
    return super.noSuchMethod(y);
  }
}

Remove the unnecessary declaration:

class A {
  @override
  dynamic noSuchMethod(x) => super.noSuchMethod(x);
}
class B extends A {}