Add option to require-default-props to forbid default props for required props

[sharmilajesupaul]

The require-default-props rule allows required props to also have a default prop. It would be nice to add an option to warn against this behavior.

Option:
forbidDefaultForRequired (boolean) - Setting this to true will forbid required props from also having a default prop declaration. Default false.

schema: [{
 type: 'object',
      properties: {
        forbidDefaultForRequired: {
          type: 'boolean'
        }
      },
      additionalProperties: false,
}]

The following patterns are considered warnings:

function MyStatelessComponent({ foo, bar }) {
  return <div>{foo}{bar}</div>;
}

MyStatelessComponent.propTypes = {
  foo: PropTypes.string.isRequired,
};

MyStatelessComponent.defaultProps = {
  foo: 'something',
};

class Foo extends React.Component {
  render() {
    return (
      <h1>Hello, {this.props.foo}</h1>
    );
  }

  static propTypes = {
    foo: PropTypes.string,
  };

  static defaultProps = {
    foo: "foo",
  };
}

The following patterns are not considered warnings:

function MyStatelessComponent({ foo, bar }) {
  return <div>{foo}{bar}</div>;
}

MyStatelessComponent.propTypes = {
  foo: PropTypes.string,
};

MyStatelessComponent.defaultProps = {
  foo: 'something',
};

class Foo extends React.Component {
  render() {
    return (
      <h1>Hello, {this.props.foo}</h1>
    );
  }

  static propTypes = {
    foo: PropTypes.string,
  };

  static defaultProps = {
    foo: "foo",
  };
}

[ljharb]

Sound great to me - as long as it does a "safe" thing when it encounters things that aren't statically analyzeable, like imported shapes, spread props, etc. It'd also be super fancy if spread props worked when the object literal it referenced was defined in the same file.

[sharmilajesupaul]

+1 on warning on spread prop violations when the referenced object literal in the same file

Is the "safe" thing generally not warning on propTypes that aren't explicitly declared in the same file?

[ljharb]

Yes, exactly - basically, what's safe is not creating false positives.