有两个钩子，widget_text 和dynamic_sidebar_params. 您可以使用其中一个。

add_filter( \'widget_text\', \'wpse219770_filter_widget_text\', 1, 3 );
    function wpse219770_filter_widget_text( $widget_text, $instance, $widget )
    {
        $tag = \'bartag\';//shortcode tag
        if ( \'text-2\' == $widget->id && has_shortcode( $instance[\'text\'], $tag ) )
            remove_shortcode( $tag );
        else
            add_shortcode( $tag, \'bartag_func\' );

        return $widget_text;
    }

add_action( \'dynamic_sidebar_params\', \'wpse219770_dynamic_sidebar_params_hook\', 1, 1 );
function wpse219770_dynamic_sidebar_params_hook( $content )
{
    //print_r( $content ) and use it for conditional

    $tag = \'bartag\';
    if ( shortcode_exists( $tag ) )
        remove_shortcode( $tag );

    return $content;
}