Enable Comments on Custom Post Types in WordPress

By default WordPress blocks comments on Custom Post Types. To enable comments on a custom post type, add comments under supports where you register it (line 32):

function snippet_custom_init() {
      $labels = array(
          'name' => 'Snippet',
          'singular_name' => 'Snippet',
          'add_new' => 'Add New Snippet',
          'add_new_item' => 'Add New Snippet',
          'edit_item' => 'Edit Snippet',
          'new_item' => 'New Snippet',
          'all_items' => 'All Snippets',
          'view_item' => 'View Snippet',
          'search_items' => 'Search Snippets',
          'not_found' =>  'No snippets found',
          'not_found_in_trash' => 'No snippets found in trash',
          'parent_item_colon' => '',
          'menu_name' => 'Snippets',
          );

      $args = array(
          'labels' => $labels,
          'exclude_from_search' => false,
          'public' => true,
          'publicly_queryable' => true,
          'show_ui' => true,
          'show_in_menu' => true,
          'query_var' => true,
          'rewrite' => array( 'slug' => 'snippet' ),
          'capability_type' => 'post',
          'has_archive' => true,
          'hierarchical' => false,
          'taxonomies' => array('category'),
          'menu_position' => null,
          'supports' => array( 'title', 'author', 'thumbnail', 'excerpt', 'comments', 'editor' )
          );

        register_post_type( 'snippet', $args );
    }
add_action( 'init', 'snippet_custom_init', 0);