This DEV-only field was added in 836331ba5f69f2cc53b273ec073fae116db14302 by @sebmarkbage but it's not being used anymore to my knowledge.
'Function components cannot be given refs. ' +
            'Attempts to access this ref will fail. ' +
            'Did you mean to use React.forwardRef()?%s',
          info,
        );
      }
    }
    if (
      warnAboutDefaultPropsOnFunctionComponents &&
      Component.defaultProps !== undefined
    ) {
      const componentName = getComponentNameFromType(Component) || 'Unknown';
      if (!didWarnAboutDefaultPropsOnFunctionComponent[componentName]) {
        console.error(
          '%s: Support for defaultProps will be removed from function components ' +
            'in a future major release. Use JavaScript default parameters instead.',
          componentName,
        );
        didWarnAboutDefaultPropsOnFunctionComponent[componentName] = true;
      }
    }
    if (typeof Component.getDerivedStateFromProps === 'function') {
      const componentName = getComponentNameFromType(Component) || 'Unknown';
      if (!didWarnAboutGetDerivedStateOnFunctionComponent[componentName]) {
        console.error(
          '%s: Function components do not support getDerivedStateFromProps.',
          componentName,
        );
        didWarnAboutGetDerivedStateOnFunctionComponent[componentName] = true;
      }