This DEV-only field was added in 836331ba5f69f2cc53b273ec073fae116db14302 by @sebmarkbage but it's not being used anymore to my knowledge.
render() {
        return React.createElement(FunctionComponent, {
          name: 'A',
          ref: () => {},
        });
      }
    }
    Object.defineProperty(AnonymousParentNotUsingJSX, 'name', {
      value: undefined,
    });
    let instance2;
    expect(() => {
      instance2 = ReactTestUtils.renderIntoDocument(
        <AnonymousParentNotUsingJSX />,
      );
    }).toErrorDev('Warning: Function components cannot be given refs.');
    
    instance2.forceUpdate();
    
    expect(() =>
      ReactTestUtils.renderIntoDocument(<AnonymousParentNotUsingJSX />),
    ).toErrorDev('Warning: Function components cannot be given refs.');
    
    class NamedParentNotUsingJSX extends React.Component {