How to use $variables from theme setting in main menu I make some field in theme setting and can use them normali in block, page, but when I want to use them in main menu its dont work. 

function saka_theme_preprocess_menu__main (&amp;$variables, $hook) {

    $variables['social_url_fb'] = theme_get_setting('social_url_fb','saka_theme');

}


and in menu--main.html.twig I write this..

{% for item in items %}
                &lt;li {{ item.attributes }} &gt;
                    &lt;a  href="{{ item.url }}"  {{ item.attributes }} &gt; {{ item.title }}&lt;/a&gt;
                &lt;/li&gt;
                &lt;li&gt;
                    &lt;a href="{{ social_url_fb }}" class="btn-social-menu"&gt;&lt;i class="fa fa-2x fa-facebook"&gt;&lt;/i&gt;&lt;/a&gt;
                &lt;/li&gt;
        {% endfor %}
You can't use name suggestions with double underscore in preprocess function names.

You have to replace this with an if statement in code:

function saka_theme_preprocess_menu(&amp;$variables) {
  if ($variables['menu_name'] == 'main') {
    $variables['social_url_fb'] = theme_get_setting('social_url_fb','saka_theme');
  }
}