no-unused-prop-types: support shouldComponentUpdate nextProps

[xareelee]

type LoginMsgContainerProps = {
  getMsgCodeErrorMsg?: string,
};

class LoginMsgContainer extends React.Component {

  props: LoginMsgContainerProps;

  shouldComponentUpdate(props: LoginMsgContainerProps) {
    if (props.getMsgCodeErrorMsg && props.getMsgCodeErrorMsg.length > 0) {
      this.toast.show(props.getMsgCodeErrorMsg);
    }
  }

  ...
}

I only use prop getMsgCodeErrorMsg in the method shouldComponentUpdate, but the linter raises a react/no-unused-prop-types error (false positive).

[ljharb]

shouldComponentUpdate takes nextProps - what happens if you name the argument that?

[xareelee]

@ljharb changing the param name doesn't help.

The linter reports the error on the line where I declare the type:

type LoginMsgContainerProps = {
  getMsgCodeErrorMsg?: string,   // The linter raises the error on this line and column 24 
};

  18:24  error  'getMsgCodeErrorMsg' PropType is defined but prop is never used
                                  react/no-unused-prop-types

I use the same type for both React component's props and the method shouldComponentUpdate ().

[ljharb]

If instead of a Flow type, you used standard .propTypes, do you get the same error?

[xareelee]

@ljharb yes, get the same error with .propTypes. I did not find that.

It produces both react/require-default-props and react/no-unused-prop-types errors, no matter using flowtype or .propTypes.

I reported react/require-default-props error on a separated issue #1212.

[ljharb]

Thanks, it seems like we need to make no-unused-prop-types work with shouldComponentUpdate.

[xareelee]

@ljharb OK, thanks.

Any workaround about this bug for now?

[ljharb]

The workaround would be an eslint override comment.

[ljharb]

#1232 hopefully has solved this; we can reopen after the next release if not.