答案是：通过电子邮件禁用标准身份验证，并通过首先尝试查找电子邮件来更新用户名。

remove_filter( \'authenticate\', \'wp_authenticate_email_password\', 100 );
add_action(\'wp_authenticate\',\'login_verification\'); 

function login_verification($username) { 
    $username = sanitize_user( $username );
    //check if this is an email 
    $user = get_user_by(\'email\',$username);  
    if(!empty($user->user_login)) {  
        $username = $user->user_login; 
    }
    //else just leave as username
    return $username;  
}