wp/wp-includes/category-template.php
changeset 7 cf61fcea0001
parent 5 5e2f62d02dcd
child 9 177826044cd9
--- a/wp/wp-includes/category-template.php	Tue Jun 09 11:14:17 2015 +0000
+++ b/wp/wp-includes/category-template.php	Mon Oct 14 17:39:30 2019 +0200
@@ -1,9 +1,10 @@
 <?php
 /**
- * Category Template Tags and API.
+ * Taxonomy API: Core category-specific template tags
  *
  * @package WordPress
  * @subpackage Template
+ * @since 1.2.0
  */
 
 /**
@@ -19,7 +20,7 @@
 	if ( ! is_object( $category ) )
 		$category = (int) $category;
 
-	$category = get_term_link( $category, 'category' );
+	$category = get_term_link( $category );
 
 	if ( is_wp_error( $category ) )
 		return '';
@@ -31,44 +32,44 @@
  * Retrieve category parents with separator.
  *
  * @since 1.2.0
+ * @since 4.8.0 The `$visited` parameter was deprecated and renamed to `$deprecated`.
  *
  * @param int $id Category ID.
  * @param bool $link Optional, default is false. Whether to format with link.
  * @param string $separator Optional, default is '/'. How to separate categories.
  * @param bool $nicename Optional, default is false. Whether to use nice name for display.
- * @param array $visited Optional. Already linked to categories to prevent duplicates.
+ * @param array $deprecated Not used.
  * @return string|WP_Error A list of category parents on success, WP_Error on failure.
  */
-function get_category_parents( $id, $link = false, $separator = '/', $nicename = false, $visited = array() ) {
-	$chain = '';
-	$parent = get_term( $id, 'category' );
-	if ( is_wp_error( $parent ) )
-		return $parent;
+function get_category_parents( $id, $link = false, $separator = '/', $nicename = false, $deprecated = array() ) {
 
-	if ( $nicename )
-		$name = $parent->slug;
-	else
-		$name = $parent->name;
-
-	if ( $parent->parent && ( $parent->parent != $parent->term_id ) && !in_array( $parent->parent, $visited ) ) {
-		$visited[] = $parent->parent;
-		$chain .= get_category_parents( $parent->parent, $link, $separator, $nicename, $visited );
+	if ( ! empty( $deprecated ) ) {
+		_deprecated_argument( __FUNCTION__, '4.8.0' );
 	}
 
-	if ( $link )
-		$chain .= '<a href="' . esc_url( get_category_link( $parent->term_id ) ) . '">'.$name.'</a>' . $separator;
-	else
-		$chain .= $name.$separator;
-	return $chain;
+	$format = $nicename ? 'slug' : 'name';
+
+	$args = array(
+		'separator' => $separator,
+		'link'      => $link,
+		'format'    => $format,
+	);
+
+	return get_term_parents_list( $id, 'category', $args );
 }
 
 /**
  * Retrieve post categories.
  *
+ * This tag may be used outside The Loop by passing a post id as the parameter.
+ *
+ * Note: This function only returns results from the default "category" taxonomy.
+ * For custom taxonomies use get_the_terms().
+ *
  * @since 0.71
  *
  * @param int $id Optional, default to current post ID. The post ID.
- * @return array
+ * @return array Array of WP_Term objects, one for each category assigned to the post.
  */
 function get_the_category( $id = false ) {
 	$categories = get_the_terms( $id, 'category' );
@@ -82,52 +83,15 @@
 	}
 
 	/**
-	 * Filter the array of categories to return for a post.
+	 * Filters the array of categories to return for a post.
 	 *
 	 * @since 3.1.0
+	 * @since 4.4.0 Added `$id` parameter.
 	 *
 	 * @param array $categories An array of categories to return for the post.
+	 * @param int   $id         ID of the post.
 	 */
-	return apply_filters( 'get_the_categories', $categories );
-}
-
-/**
- * Sort categories by name.
- *
- * Used by usort() as a callback, should not be used directly. Can actually be
- * used to sort any term object.
- *
- * @since 2.3.0
- * @access private
- *
- * @param object $a
- * @param object $b
- * @return int
- */
-function _usort_terms_by_name( $a, $b ) {
-	return strcmp( $a->name, $b->name );
-}
-
-/**
- * Sort categories by ID.
- *
- * Used by usort() as a callback, should not be used directly. Can actually be
- * used to sort any term object.
- *
- * @since 2.3.0
- * @access private
- *
- * @param object $a
- * @param object $b
- * @return int
- */
-function _usort_terms_by_ID( $a, $b ) {
-	if ( $a->term_id > $b->term_id )
-		return 1;
-	elseif ( $a->term_id < $b->term_id )
-		return -1;
-	else
-		return 0;
+	return apply_filters( 'get_the_categories', $categories, $id );
 }
 
 /**
@@ -140,7 +104,7 @@
  */
 function get_the_category_by_ID( $cat_ID ) {
 	$cat_ID = (int) $cat_ID;
-	$category = get_term( $cat_ID, 'category' );
+	$category = get_term( $cat_ID );
 
 	if ( is_wp_error( $category ) )
 		return $category;
@@ -149,23 +113,36 @@
 }
 
 /**
- * Retrieve category list in either HTML list or custom format.
+ * Retrieve category list for a post in either HTML list or custom format.
  *
  * @since 1.5.1
  *
- * @param string $separator Optional, default is empty string. Separator for between the categories.
+ * @global WP_Rewrite $wp_rewrite
+ *
+ * @param string $separator Optional. Separator between the categories. By default, the links are placed
+ *                          in an unordered list. An empty string will result in the default behavior.
  * @param string $parents Optional. How to display the parents.
  * @param int $post_id Optional. Post ID to retrieve categories.
  * @return string
  */
-function get_the_category_list( $separator = '', $parents='', $post_id = false ) {
+function get_the_category_list( $separator = '', $parents = '', $post_id = false ) {
 	global $wp_rewrite;
 	if ( ! is_object_in_taxonomy( get_post_type( $post_id ), 'category' ) ) {
 		/** This filter is documented in wp-includes/category-template.php */
 		return apply_filters( 'the_category', '', $separator, $parents );
 	}
 
-	$categories = get_the_category( $post_id );
+	/**
+	 * Filters the categories before building the category list.
+	 *
+	 * @since 4.4.0
+	 *
+	 * @param array    $categories An array of the post's categories.
+	 * @param int|bool $post_id    ID of the post we're retrieving categories for. When `false`, we assume the
+	 *                             current post in the loop.
+	 */
+	$categories = apply_filters( 'the_category_list', get_the_category( $post_id ), $post_id );
+
 	if ( empty( $categories ) ) {
 		/** This filter is documented in wp-includes/category-template.php */
 		return apply_filters( 'the_category', __( 'Uncategorized' ), $separator, $parents );
@@ -222,11 +199,11 @@
 	}
 
 	/**
-	 * Filter the category or list of categories.
+	 * Filters the category or list of categories.
 	 *
 	 * @since 1.2.0
 	 *
-	 * @param array  $thelist   List of categories for the current post.
+	 * @param string $thelist   List of categories for the current post.
 	 * @param string $separator Separator used between the categories.
 	 * @param string $parents   How to display the category parents. Accepts 'multiple',
 	 *                          'single', or empty.
@@ -235,7 +212,7 @@
 }
 
 /**
- * Check if the current post in within any of the given categories.
+ * Check if the current post is within any of the given categories.
  *
  * The given categories are checked against the post's categories' term_ids, names and slugs.
  * Categories given as integers will only be checked against the post's categories' term_ids.
@@ -260,15 +237,16 @@
 }
 
 /**
- * Display the category list for the post.
+ * Display category list for a post in either HTML list or custom format.
  *
  * @since 0.71
  *
- * @param string $separator Optional, default is empty string. Separator for between the categories.
+ * @param string $separator Optional. Separator between the categories. By default, the links are placed
+ *                          in an unordered list. An empty string will result in the default behavior.
  * @param string $parents Optional. How to display the parents.
  * @param int $post_id Optional. Post ID to retrieve categories.
  */
-function the_category( $separator = '', $parents='', $post_id = false ) {
+function the_category( $separator = '', $parents = '', $post_id = false ) {
 	echo get_the_category_list( $separator, $parents, $post_id );
 }
 
@@ -294,25 +272,20 @@
  *
  * @since 2.1.0
  * @since 4.2.0 Introduced the `value_field` argument.
+ * @since 4.6.0 Introduced the `required` argument.
  *
  * @param string|array $args {
- *     Optional. Array or string of arguments to generate a categories drop-down element.
+ *     Optional. Array or string of arguments to generate a categories drop-down element. See WP_Term_Query::__construct()
+ *     for information on additional accepted arguments.
  *
  *     @type string       $show_option_all   Text to display for showing all categories. Default empty.
  *     @type string       $show_option_none  Text to display for showing no categories. Default empty.
  *     @type string       $option_none_value Value to use when no category is selected. Default empty.
  *     @type string       $orderby           Which column to use for ordering categories. See get_terms() for a list
  *                                           of accepted values. Default 'id' (term_id).
- *     @type string       $order             Whether to order terms in ascending or descending order. Accepts 'ASC'
- *                                           or 'DESC'. Default 'ASC'.
  *     @type bool         $pad_counts        See get_terms() for an argument description. Default false.
  *     @type bool|int     $show_count        Whether to include post counts. Accepts 0, 1, or their bool equivalents.
  *                                           Default 0.
- *     @type bool|int     $hide_empty        Whether to hide categories that don't have any posts. Accepts 0, 1, or
- *                                           their bool equivalents. Default 1.
- *     @type int          $child_of          Term ID to retrieve child terms of. See get_terms(). Default 0.
- *     @type array|string $exclude           Array or comma/space-separated string of term ids to exclude.
- *                                           If `$include` is non-empty, `$exclude` is ignored. Default empty array.
  *     @type bool|int     $echo              Whether to echo or return the generated markup. Accepts 0, 1, or their
  *                                           bool equivalents. Default 1.
  *     @type bool|int     $hierarchical      Whether to traverse the taxonomy hierarchy. Accepts 0, 1, or their bool
@@ -328,32 +301,50 @@
  *                                           of the option elements. Accepts any valid term field: 'term_id', 'name',
  *                                           'slug', 'term_group', 'term_taxonomy_id', 'taxonomy', 'description',
  *                                           'parent', 'count'. Default 'term_id'.
- *     @type string       $taxonomy          Name of the category to retrieve. Default 'category'.
+ *     @type string|array $taxonomy          Name of the category or categories to retrieve. Default 'category'.
  *     @type bool         $hide_if_empty     True to skip generating markup if no categories are found.
  *                                           Default false (create select element even if no categories are found).
+ *     @type bool         $required          Whether the `<select>` element should have the HTML5 'required' attribute.
+ *                                           Default false.
  * }
  * @return string HTML content only if 'echo' argument is 0.
  */
 function wp_dropdown_categories( $args = '' ) {
 	$defaults = array(
-		'show_option_all' => '', 'show_option_none' => '',
-		'orderby' => 'id', 'order' => 'ASC',
-		'show_count' => 0,
-		'hide_empty' => 1, 'child_of' => 0,
-		'exclude' => '', 'echo' => 1,
-		'selected' => 0, 'hierarchical' => 0,
-		'name' => 'cat', 'id' => '',
-		'class' => 'postform', 'depth' => 0,
-		'tab_index' => 0, 'taxonomy' => 'category',
-		'hide_if_empty' => false, 'option_none_value' => -1,
-		'value_field' => 'term_id',
+		'show_option_all'   => '',
+		'show_option_none'  => '',
+		'orderby'           => 'id',
+		'order'             => 'ASC',
+		'show_count'        => 0,
+		'hide_empty'        => 1,
+		'child_of'          => 0,
+		'exclude'           => '',
+		'echo'              => 1,
+		'selected'          => 0,
+		'hierarchical'      => 0,
+		'name'              => 'cat',
+		'id'                => '',
+		'class'             => 'postform',
+		'depth'             => 0,
+		'tab_index'         => 0,
+		'taxonomy'          => 'category',
+		'hide_if_empty'     => false,
+		'option_none_value' => -1,
+		'value_field'       => 'term_id',
+		'required'          => false,
 	);
 
 	$defaults['selected'] = ( is_category() ) ? get_query_var( 'cat' ) : 0;
 
 	// Back compat.
 	if ( isset( $args['type'] ) && 'link' == $args['type'] ) {
-		_deprecated_argument( __FUNCTION__, '3.0', '' );
+		_deprecated_argument( __FUNCTION__, '3.0.0',
+			/* translators: 1: "type => link", 2: "taxonomy => link_category" */
+			sprintf( __( '%1$s is deprecated. Use %2$s instead.' ),
+				'<code>type => link</code>',
+				'<code>taxonomy => link_category</code>'
+			)
+		);
 		$args['taxonomy'] = 'link_category';
 	}
 
@@ -379,16 +370,17 @@
 	$name = esc_attr( $r['name'] );
 	$class = esc_attr( $r['class'] );
 	$id = $r['id'] ? esc_attr( $r['id'] ) : $name;
+	$required = $r['required'] ? 'required' : '';
 
 	if ( ! $r['hide_if_empty'] || ! empty( $categories ) ) {
-		$output = "<select name='$name' id='$id' class='$class' $tab_index_attribute>\n";
+		$output = "<select $required name='$name' id='$id' class='$class' $tab_index_attribute>\n";
 	} else {
 		$output = '';
 	}
 	if ( empty( $categories ) && ! $r['hide_if_empty'] && ! empty( $r['show_option_none'] ) ) {
 
 		/**
-		 * Filter a taxonomy drop-down display element.
+		 * Filters a taxonomy drop-down display element.
 		 *
 		 * A variety of taxonomy drop-down display elements can be modified
 		 * just prior to display via this filter. Filterable arguments include
@@ -399,9 +391,10 @@
 		 *
 		 * @see wp_dropdown_categories()
 		 *
-		 * @param string $element Taxonomy element to list.
+		 * @param string       $element  Category name.
+		 * @param WP_Term|null $category The category object, or null if there's no corresponding category.
 		 */
-		$show_option_none = apply_filters( 'list_cats', $r['show_option_none'] );
+		$show_option_none = apply_filters( 'list_cats', $r['show_option_none'], null );
 		$output .= "\t<option value='" . esc_attr( $option_none_value ) . "' selected='selected'>$show_option_none</option>\n";
 	}
 
@@ -410,7 +403,7 @@
 		if ( $r['show_option_all'] ) {
 
 			/** This filter is documented in wp-includes/category-template.php */
-			$show_option_all = apply_filters( 'list_cats', $r['show_option_all'] );
+			$show_option_all = apply_filters( 'list_cats', $r['show_option_all'], null );
 			$selected = ( '0' === strval($r['selected']) ) ? " selected='selected'" : '';
 			$output .= "\t<option value='0'$selected>$show_option_all</option>\n";
 		}
@@ -418,7 +411,7 @@
 		if ( $r['show_option_none'] ) {
 
 			/** This filter is documented in wp-includes/category-template.php */
-			$show_option_none = apply_filters( 'list_cats', $r['show_option_none'] );
+			$show_option_none = apply_filters( 'list_cats', $r['show_option_none'], null );
 			$selected = selected( $option_none_value, $r['selected'], false );
 			$output .= "\t<option value='" . esc_attr( $option_none_value ) . "'$selected>$show_option_none</option>\n";
 		}
@@ -435,7 +428,7 @@
 		$output .= "</select>\n";
 	}
 	/**
-	 * Filter the taxonomy drop-down output.
+	 * Filters the taxonomy drop-down output.
 	 *
 	 * @since 2.1.0
 	 *
@@ -453,47 +446,78 @@
 /**
  * Display or retrieve the HTML list of categories.
  *
- * The list of arguments is below:
- *     'show_option_all' (string) - Text to display for showing all categories.
- *     'orderby' (string) default is 'ID' - What column to use for ordering the
- * categories.
- *     'order' (string) default is 'ASC' - What direction to order categories.
- *     'show_count' (bool|int) default is 0 - Whether to show how many posts are
- * in the category.
- *     'hide_empty' (bool|int) default is 1 - Whether to hide categories that
- * don't have any posts attached to them.
- *     'use_desc_for_title' (bool|int) default is 1 - Whether to use the
- * category description as the title attribute.
- *     'feed' - See {@link get_categories()}.
- *     'feed_type' - See {@link get_categories()}.
- *     'feed_image' - See {@link get_categories()}.
- *     'child_of' (int) default is 0 - See {@link get_categories()}.
- *     'exclude' (string) - See {@link get_categories()}.
- *     'exclude_tree' (string) - See {@link get_categories()}.
- *     'echo' (bool|int) default is 1 - Whether to display or retrieve content.
- *     'current_category' (int) - See {@link get_categories()}.
- *     'hierarchical' (bool) - See {@link get_categories()}.
- *     'title_li' (string) - See {@link get_categories()}.
- *     'depth' (int) - The max depth.
+ * @since 2.1.0
+ * @since 4.4.0 Introduced the `hide_title_if_empty` and `separator` arguments. The `current_category` argument was modified to
+ *              optionally accept an array of values.
+ *
+ * @param string|array $args {
+ *     Array of optional arguments.
  *
- * @since 2.1.0
- *
- * @param string|array $args Optional. Override default arguments.
- * @return false|null|string HTML content only if 'echo' argument is 0.
+ *     @type int          $child_of              Term ID to retrieve child terms of. See get_terms(). Default 0.
+ *     @type int|array    $current_category      ID of category, or array of IDs of categories, that should get the
+ *                                               'current-cat' class. Default 0.
+ *     @type int          $depth                 Category depth. Used for tab indentation. Default 0.
+ *     @type bool|int     $echo                  True to echo markup, false to return it. Default 1.
+ *     @type array|string $exclude               Array or comma/space-separated string of term IDs to exclude.
+ *                                               If `$hierarchical` is true, descendants of `$exclude` terms will also
+ *                                               be excluded; see `$exclude_tree`. See get_terms().
+ *                                               Default empty string.
+ *     @type array|string $exclude_tree          Array or comma/space-separated string of term IDs to exclude, along
+ *                                               with their descendants. See get_terms(). Default empty string.
+ *     @type string       $feed                  Text to use for the feed link. Default 'Feed for all posts filed
+ *                                               under [cat name]'.
+ *     @type string       $feed_image            URL of an image to use for the feed link. Default empty string.
+ *     @type string       $feed_type             Feed type. Used to build feed link. See get_term_feed_link().
+ *                                               Default empty string (default feed).
+ *     @type bool|int     $hide_empty            Whether to hide categories that don't have any posts attached to them.
+ *                                               Default 1.
+ *     @type bool         $hide_title_if_empty   Whether to hide the `$title_li` element if there are no terms in
+ *                                               the list. Default false (title will always be shown).
+ *     @type bool         $hierarchical          Whether to include terms that have non-empty descendants.
+ *                                               See get_terms(). Default true.
+ *     @type string       $order                 Which direction to order categories. Accepts 'ASC' or 'DESC'.
+ *                                               Default 'ASC'.
+ *     @type string       $orderby               The column to use for ordering categories. Default 'name'.
+ *     @type string       $separator             Separator between links. Default '<br />'.
+ *     @type bool|int     $show_count            Whether to show how many posts are in the category. Default 0.
+ *     @type string       $show_option_all       Text to display for showing all categories. Default empty string.
+ *     @type string       $show_option_none      Text to display for the 'no categories' option.
+ *                                               Default 'No categories'.
+ *     @type string       $style                 The style used to display the categories list. If 'list', categories
+ *                                               will be output as an unordered list. If left empty or another value,
+ *                                               categories will be output separated by `<br>` tags. Default 'list'.
+ *     @type string       $taxonomy              Taxonomy name. Default 'category'.
+ *     @type string       $title_li              Text to use for the list title `<li>` element. Pass an empty string
+ *                                               to disable. Default 'Categories'.
+ *     @type bool|int     $use_desc_for_title    Whether to use the category description as the title attribute.
+ *                                               Default 1.
+ * }
+ * @return false|string HTML content only if 'echo' argument is 0.
  */
 function wp_list_categories( $args = '' ) {
 	$defaults = array(
-		'show_option_all' => '', 'show_option_none' => __('No categories'),
-		'orderby' => 'name', 'order' => 'ASC',
-		'style' => 'list',
-		'show_count' => 0, 'hide_empty' => 1,
-		'use_desc_for_title' => 1, 'child_of' => 0,
-		'feed' => '', 'feed_type' => '',
-		'feed_image' => '', 'exclude' => '',
-		'exclude_tree' => '', 'current_category' => 0,
-		'hierarchical' => true, 'title_li' => __( 'Categories' ),
-		'echo' => 1, 'depth' => 0,
-		'taxonomy' => 'category'
+		'child_of'            => 0,
+		'current_category'    => 0,
+		'depth'               => 0,
+		'echo'                => 1,
+		'exclude'             => '',
+		'exclude_tree'        => '',
+		'feed'                => '',
+		'feed_image'          => '',
+		'feed_type'           => '',
+		'hide_empty'          => 1,
+		'hide_title_if_empty' => false,
+		'hierarchical'        => true,
+		'order'               => 'ASC',
+		'orderby'             => 'name',
+		'separator'           => '<br />',
+		'show_count'          => 0,
+		'show_option_all'     => '',
+		'show_option_none'    => __( 'No categories' ),
+		'style'               => 'list',
+		'taxonomy'            => 'category',
+		'title_li'            => __( 'Categories' ),
+		'use_desc_for_title'  => 1,
 	);
 
 	$r = wp_parse_args( $args, $defaults );
@@ -501,8 +525,19 @@
 	if ( !isset( $r['pad_counts'] ) && $r['show_count'] && $r['hierarchical'] )
 		$r['pad_counts'] = true;
 
+	// Descendants of exclusions should be excluded too.
 	if ( true == $r['hierarchical'] ) {
-		$r['exclude_tree'] = $r['exclude'];
+		$exclude_tree = array();
+
+		if ( $r['exclude_tree'] ) {
+			$exclude_tree = array_merge( $exclude_tree, wp_parse_id_list( $r['exclude_tree'] ) );
+		}
+
+		if ( $r['exclude'] ) {
+			$exclude_tree = array_merge( $exclude_tree, wp_parse_id_list( $r['exclude'] ) );
+		}
+
+		$r['exclude_tree'] = $exclude_tree;
 		$r['exclude'] = '';
 	}
 
@@ -519,7 +554,7 @@
 	$categories = get_categories( $r );
 
 	$output = '';
-	if ( $r['title_li'] && 'list' == $r['style'] ) {
+	if ( $r['title_li'] && 'list' == $r['style'] && ( ! empty( $categories ) || ! $r['hide_title_if_empty'] ) ) {
 		$output = '<li class="' . esc_attr( $r['class'] ) . '">' . $r['title_li'] . '<ul>';
 	}
 	if ( empty( $categories ) ) {
@@ -532,7 +567,32 @@
 		}
 	} else {
 		if ( ! empty( $show_option_all ) ) {
-			$posts_page = ( 'page' == get_option( 'show_on_front' ) && get_option( 'page_for_posts' ) ) ? get_permalink( get_option( 'page_for_posts' ) ) : home_url( '/' );
+
+			$posts_page = '';
+
+			// For taxonomies that belong only to custom post types, point to a valid archive.
+			$taxonomy_object = get_taxonomy( $r['taxonomy'] );
+			if ( ! in_array( 'post', $taxonomy_object->object_type ) && ! in_array( 'page', $taxonomy_object->object_type ) ) {
+				foreach ( $taxonomy_object->object_type as $object_type ) {
+					$_object_type = get_post_type_object( $object_type );
+
+					// Grab the first one.
+					if ( ! empty( $_object_type->has_archive ) ) {
+						$posts_page = get_post_type_archive_link( $object_type );
+						break;
+					}
+				}
+			}
+
+			// Fallback for the 'All' link is the posts page.
+			if ( ! $posts_page ) {
+				if ( 'page' == get_option( 'show_on_front' ) && get_option( 'page_for_posts' ) ) {
+					$posts_page = get_permalink( get_option( 'page_for_posts' ) );
+				} else {
+					$posts_page = home_url( '/' );
+				}
+			}
+
 			$posts_page = esc_url( $posts_page );
 			if ( 'list' == $r['style'] ) {
 				$output .= "<li class='cat-item-all'><a href='$posts_page'>$show_option_all</a></li>";
@@ -556,11 +616,12 @@
 		$output .= walk_category_tree( $categories, $depth, $r );
 	}
 
-	if ( $r['title_li'] && 'list' == $r['style'] )
+	if ( $r['title_li'] && 'list' == $r['style'] && ( ! empty( $categories ) || ! $r['hide_title_if_empty'] ) ) {
 		$output .= '</ul></li>';
+	}
 
 	/**
-	 * Filter the HTML output of a taxonomy list.
+	 * Filters the HTML output of a taxonomy list.
 	 *
 	 * @since 2.1.0
 	 *
@@ -593,28 +654,30 @@
  * be to return the top 45 tags in the tag cloud list.
  *
  * The 'topic_count_text' argument is a nooped plural from _n_noop() to generate the
- * text for the tooltip of the tag link.
+ * text for the tag link count.
  *
  * The 'topic_count_text_callback' argument is a function, which given the count
- * of the posts with that tag returns a text for the tooltip of the tag link.
+ * of the posts with that tag returns a text for the tag link count.
  *
  * The 'post_type' argument is used only when 'link' is set to 'edit'. It determines the post_type
  * passed to edit.php for the popular tags edit links.
  *
- * The 'exclude' and 'include' arguments are used for the {@link get_tags()}
- * function. Only one should be used, because only one will be used and the
- * other ignored, if they are both set.
+ * The 'exclude' and 'include' arguments are used for the get_tags() function. Only one
+ * should be used, because only one will be used and the other ignored, if they are both set.
  *
  * @since 2.3.0
+ * @since 4.8.0 Added the `show_count` argument.
  *
  * @param array|string|null $args Optional. Override default arguments.
- * @return null|false Generated tag cloud, only if no failures and 'array' is set for the 'format' argument.
+ * @return void|array Generated tag cloud, only if no failures and 'array' is set for the 'format' argument.
+ *                    Otherwise, this function outputs the tag cloud.
  */
 function wp_tag_cloud( $args = '' ) {
 	$defaults = array(
 		'smallest' => 8, 'largest' => 22, 'unit' => 'pt', 'number' => 45,
 		'format' => 'flat', 'separator' => "\n", 'orderby' => 'name', 'order' => 'ASC',
-		'exclude' => '', 'include' => '', 'link' => 'view', 'taxonomy' => 'post_tag', 'post_type' => '', 'echo' => true
+		'exclude' => '', 'include' => '', 'link' => 'view', 'taxonomy' => 'post_tag', 'post_type' => '', 'echo' => true,
+		'show_count' => 0,
 	);
 	$args = wp_parse_args( $args, $defaults );
 
@@ -629,7 +692,7 @@
 		else
 			$link = get_term_link( intval($tag->term_id), $tag->taxonomy );
 		if ( is_wp_error( $link ) )
-			return false;
+			return;
 
 		$tags[ $key ]->link = $link;
 		$tags[ $key ]->id = $tag->term_id;
@@ -638,7 +701,7 @@
 	$return = wp_generate_tag_cloud( $tags, $args ); // Here's where those top tags get sorted according to $args
 
 	/**
-	 * Filter the tag cloud output.
+	 * Filters the tag cloud output.
 	 *
 	 * @since 2.3.0
 	 *
@@ -654,10 +717,12 @@
 }
 
 /**
- * Default topic count scaling for tag links
+ * Default topic count scaling for tag links.
  *
- * @param integer $count number of posts with that tag
- * @return integer scaled count
+ * @since 2.9.0
+ *
+ * @param int $count Number of posts with that tag.
+ * @return int Scaled count.
  */
 function default_topic_count_scale( $count ) {
 	return round(log10($count + 1) * 100);
@@ -666,35 +731,47 @@
 /**
  * Generates a tag cloud (heatmap) from provided data.
  *
- * The text size is set by the 'smallest' and 'largest' arguments, which will
- * use the 'unit' argument value for the CSS text size unit. The 'format'
- * argument can be 'flat' (default), 'list', or 'array'. The flat value for the
- * 'format' argument will separate tags with spaces. The list value for the
- * 'format' argument will format the tags in a UL HTML list. The array value for
- * the 'format' argument will return in PHP array type format.
- *
- * The 'tag_cloud_sort' filter allows you to override the sorting.
- * Passed to the filter: $tags array and $args array, has to return the $tags array
- * after sorting it.
- *
- * The 'orderby' argument will accept 'name' or 'count' and defaults to 'name'.
- * The 'order' is the direction to sort, defaults to 'ASC' and can be 'DESC' or
- * 'RAND'.
- *
- * The 'number' argument is how many tags to return. By default, the limit will
- * be to return the entire tag cloud list.
- *
- * The 'topic_count_text' argument is a nooped plural from _n_noop() to generate the
- * text for the tooltip of the tag link.
- *
- * The 'topic_count_text_callback' argument is a function, which given the count
- * of the posts with that tag returns a text for the tooltip of the tag link.
- *
  * @todo Complete functionality.
  * @since 2.3.0
+ * @since 4.8.0 Added the `show_count` argument.
  *
  * @param array $tags List of tags.
- * @param string|array $args Optional, override default arguments.
+ * @param string|array $args {
+ *     Optional. Array of string of arguments for generating a tag cloud.
+ *
+ *     @type int      $smallest                   Smallest font size used to display tags. Paired
+ *                                                with the value of `$unit`, to determine CSS text
+ *                                                size unit. Default 8 (pt).
+ *     @type int      $largest                    Largest font size used to display tags. Paired
+ *                                                with the value of `$unit`, to determine CSS text
+ *                                                size unit. Default 22 (pt).
+ *     @type string   $unit                       CSS text size unit to use with the `$smallest`
+ *                                                and `$largest` values. Accepts any valid CSS text
+ *                                                size unit. Default 'pt'.
+ *     @type int      $number                     The number of tags to return. Accepts any
+ *                                                positive integer or zero to return all.
+ *                                                Default 0.
+ *     @type string   $format                     Format to display the tag cloud in. Accepts 'flat'
+ *                                                (tags separated with spaces), 'list' (tags displayed
+ *                                                in an unordered list), or 'array' (returns an array).
+ *                                                Default 'flat'.
+ *     @type string   $separator                  HTML or text to separate the tags. Default "\n" (newline).
+ *     @type string   $orderby                    Value to order tags by. Accepts 'name' or 'count'.
+ *                                                Default 'name'. The {@see 'tag_cloud_sort'} filter
+ *                                                can also affect how tags are sorted.
+ *     @type string   $order                      How to order the tags. Accepts 'ASC' (ascending),
+ *                                                'DESC' (descending), or 'RAND' (random). Default 'ASC'.
+ *     @type int|bool $filter                     Whether to enable filtering of the final output
+ *                                                via {@see 'wp_generate_tag_cloud'}. Default 1|true.
+ *     @type string   $topic_count_text           Nooped plural text from _n_noop() to supply to
+ *                                                tag counts. Default null.
+ *     @type callable $topic_count_text_callback  Callback used to generate nooped plural text for
+ *                                                tag counts based on the count. Default null.
+ *     @type callable $topic_count_scale_callback Callback used to determine the tag count scaling
+ *                                                value. Default default_topic_count_scale().
+ *     @type bool|int $show_count                 Whether to display the tag counts. Default 0. Accepts
+ *                                                0, 1, or their bool equivalents.
+ * }
  * @return string|array Tag cloud as a string or an array, depending on 'format' argument.
  */
 function wp_generate_tag_cloud( $tags, $args = '' ) {
@@ -703,6 +780,7 @@
 		'format' => 'flat', 'separator' => "\n", 'orderby' => 'name', 'order' => 'ASC',
 		'topic_count_text' => null, 'topic_count_text_callback' => null,
 		'topic_count_scale_callback' => 'default_topic_count_scale', 'filter' => 1,
+		'show_count' => 0,
 	);
 
 	$args = wp_parse_args( $args, $defaults );
@@ -713,14 +791,14 @@
 		return $return;
 	}
 
-	// Juggle topic count tooltips:
+	// Juggle topic counts.
 	if ( isset( $args['topic_count_text'] ) ) {
 		// First look for nooped plural support via topic_count_text.
 		$translate_nooped_plural = $args['topic_count_text'];
 	} elseif ( ! empty( $args['topic_count_text_callback'] ) ) {
 		// Look for the alternative callback style. Ignore the previous default.
 		if ( $args['topic_count_text_callback'] === 'default_topic_count_text' ) {
-			$translate_nooped_plural = _n_noop( '%s topic', '%s topics' );
+			$translate_nooped_plural = _n_noop( '%s item', '%s items' );
 		} else {
 			$translate_nooped_plural = false;
 		}
@@ -729,11 +807,11 @@
 		$translate_nooped_plural = _n_noop( $args['single_text'], $args['multiple_text'] );
 	} else {
 		// This is the default for when no callback, plural, or argument is passed in.
-		$translate_nooped_plural = _n_noop( '%s topic', '%s topics' );
+		$translate_nooped_plural = _n_noop( '%s item', '%s items' );
 	}
 
 	/**
-	 * Filter how the items in a tag cloud are sorted.
+	 * Filters how the items in a tag cloud are sorted.
 	 *
 	 * @since 2.8.0
 	 *
@@ -784,24 +862,75 @@
 		$font_spread = 1;
 	$font_step = $font_spread / $spread;
 
-	$a = array();
+	$aria_label = false;
+	/*
+	 * Determine whether to output an 'aria-label' attribute with the tag name and count.
+	 * When tags have a different font size, they visually convey an important information
+	 * that should be available to assistive technologies too. On the other hand, sometimes
+	 * themes set up the Tag Cloud to display all tags with the same font size (setting
+	 * the 'smallest' and 'largest' arguments to the same value).
+	 * In order to always serve the same content to all users, the 'aria-label' gets printed out:
+	 * - when tags have a different size
+	 * - when the tag count is displayed (for example when users check the checkbox in the
+	 *   Tag Cloud widget), regardless of the tags font size
+	 */
+	if ( $args['show_count'] || 0 !== $font_spread ) {
+		$aria_label = true;
+	}
 
+	// Assemble the data that will be used to generate the tag cloud markup.
+	$tags_data = array();
 	foreach ( $tags as $key => $tag ) {
+		$tag_id = isset( $tag->id ) ? $tag->id : $key;
+
 		$count = $counts[ $key ];
 		$real_count = $real_counts[ $key ];
-		$tag_link = '#' != $tag->link ? esc_url( $tag->link ) : '#';
-		$tag_id = isset($tags[ $key ]->id) ? $tags[ $key ]->id : $key;
-		$tag_name = $tags[ $key ]->name;
 
 		if ( $translate_nooped_plural ) {
-			$title_attribute = sprintf( translate_nooped_plural( $translate_nooped_plural, $real_count ), number_format_i18n( $real_count ) );
+			$formatted_count = sprintf( translate_nooped_plural( $translate_nooped_plural, $real_count ), number_format_i18n( $real_count ) );
 		} else {
-			$title_attribute = call_user_func( $args['topic_count_text_callback'], $real_count, $tag, $args );
+			$formatted_count = call_user_func( $args['topic_count_text_callback'], $real_count, $tag, $args );
 		}
 
-		$a[] = "<a href='$tag_link' class='tag-link-$tag_id' title='" . esc_attr( $title_attribute ) . "' style='font-size: " .
-			str_replace( ',', '.', ( $args['smallest'] + ( ( $count - $min_count ) * $font_step ) ) )
-			. $args['unit'] . ";'>$tag_name</a>";
+		$tags_data[] = array(
+			'id'              => $tag_id,
+			'url'             => '#' != $tag->link ? $tag->link : '#',
+			'role'            => '#' != $tag->link ? '' : ' role="button"',
+			'name'            => $tag->name,
+			'formatted_count' => $formatted_count,
+			'slug'            => $tag->slug,
+			'real_count'      => $real_count,
+			'class'           => 'tag-cloud-link tag-link-' . $tag_id,
+			'font_size'       => $args['smallest'] + ( $count - $min_count ) * $font_step,
+			'aria_label'      => $aria_label ? sprintf( ' aria-label="%1$s (%2$s)"', esc_attr( $tag->name ), esc_attr( $formatted_count ) ) : '',
+			'show_count'      => $args['show_count'] ? '<span class="tag-link-count"> (' . $real_count . ')</span>' : '',
+		);
+	}
+
+	/**
+	 * Filters the data used to generate the tag cloud.
+	 *
+	 * @since 4.3.0
+	 *
+	 * @param array $tags_data An array of term data for term used to generate the tag cloud.
+	 */
+	$tags_data = apply_filters( 'wp_generate_tag_cloud_data', $tags_data );
+
+	$a = array();
+
+	// Generate the output links array.
+	foreach ( $tags_data as $key => $tag_data ) {
+		$class = $tag_data['class'] . ' tag-link-position-' . ( $key + 1 );
+		$a[] = sprintf(
+			'<a href="%1$s"%2$s class="%3$s" style="font-size: %4$s;"%5$s>%6$s%7$s</a>',
+			esc_url( $tag_data['url'] ),
+			$tag_data['role'],
+			esc_attr( $class ),
+			esc_attr( str_replace( ',', '.', $tag_data['font_size'] ) . $args['unit'] ),
+			$tag_data['aria_label'],
+			esc_html( $tag_data['name'] ),
+			$tag_data['show_count']
+		);
 	}
 
 	switch ( $args['format'] ) {
@@ -809,7 +938,12 @@
 			$return =& $a;
 			break;
 		case 'list' :
-			$return = "<ul class='wp-tag-cloud'>\n\t<li>";
+			/*
+			 * Force role="list", as some browsers (sic: Safari 10) don't expose to assistive
+			 * technologies the default role when the list is styled with `list-style: none`.
+			 * Note: this is redundant but doesn't harm.
+			 */
+			$return = "<ul class='wp-tag-cloud' role='list'>\n\t<li>";
 			$return .= join( "</li>\n\t<li>", $a );
 			$return .= "</li>\n</ul>\n";
 			break;
@@ -820,7 +954,7 @@
 
 	if ( $args['filter'] ) {
 		/**
-		 * Filter the generated output of a tag cloud.
+		 * Filters the generated output of a tag cloud.
 		 *
 		 * The filter is only evaluated if a true value is passed
 		 * to the $filter argument in wp_generate_tag_cloud().
@@ -843,20 +977,33 @@
 }
 
 /**
- * Callback for comparing objects based on name
+ * Serves as a callback for comparing objects based on name.
+ *
+ * Used with `uasort()`.
  *
  * @since 3.1.0
  * @access private
+ *
+ * @param object $a The first object to compare.
+ * @param object $b The second object to compare.
+ * @return int Negative number if `$a->name` is less than `$b->name`, zero if they are equal,
+ *             or greater than zero if `$a->name` is greater than `$b->name`.
  */
 function _wp_object_name_sort_cb( $a, $b ) {
 	return strnatcasecmp( $a->name, $b->name );
 }
 
 /**
- * Callback for comparing objects based on count
+ * Serves as a callback for comparing objects based on count.
+ *
+ * Used with `uasort()`.
  *
  * @since 3.1.0
  * @access private
+ *
+ * @param object $a The first object to compare.
+ * @param object $b The second object to compare.
+ * @return bool Whether the count value for `$a` is greater than the count value for `$b`.
  */
 function _wp_object_count_sort_cb( $a, $b ) {
 	return ( $a->count > $b->count );
@@ -872,6 +1019,7 @@
  * @uses Walker_Category to create HTML list content.
  * @since 2.1.0
  * @see Walker_Category::walk() for parameters and return description.
+ * @return string
  */
 function walk_category_tree() {
 	$args = func_get_args();
@@ -881,7 +1029,7 @@
 	} else {
 		$walker = $args[2]['walker'];
 	}
-	return call_user_func_array(array( &$walker, 'walk' ), $args );
+	return call_user_func_array( array( $walker, 'walk' ), $args );
 }
 
 /**
@@ -890,274 +1038,17 @@
  * @uses Walker_CategoryDropdown to create HTML dropdown content.
  * @since 2.1.0
  * @see Walker_CategoryDropdown::walk() for parameters and return description.
+ * @return string
  */
 function walk_category_dropdown_tree() {
 	$args = func_get_args();
 	// the user's options are the third parameter
-	if ( empty($args[2]['walker']) || !is_a($args[2]['walker'], 'Walker') )
+	if ( empty( $args[2]['walker'] ) || ! ( $args[2]['walker'] instanceof Walker ) ) {
 		$walker = new Walker_CategoryDropdown;
-	else
+	} else {
 		$walker = $args[2]['walker'];
-
-	return call_user_func_array(array( &$walker, 'walk' ), $args );
-}
-
-/**
- * Create HTML list of categories.
- *
- * @package WordPress
- * @since 2.1.0
- * @uses Walker
- */
-class Walker_Category extends Walker {
-	/**
-	 * What the class handles.
-	 *
-	 * @see Walker::$tree_type
-	 * @since 2.1.0
-	 * @var string
-	 */
-	public $tree_type = 'category';
-
-	/**
-	 * Database fields to use.
-	 *
-	 * @see Walker::$db_fields
-	 * @since 2.1.0
-	 * @todo Decouple this
-	 * @var array
-	 */
-	public $db_fields = array ('parent' => 'parent', 'id' => 'term_id');
-
-	/**
-	 * Starts the list before the elements are added.
-	 *
-	 * @see Walker::start_lvl()
-	 *
-	 * @since 2.1.0
-	 *
-	 * @param string $output Passed by reference. Used to append additional content.
-	 * @param int    $depth  Depth of category. Used for tab indentation.
-	 * @param array  $args   An array of arguments. Will only append content if style argument value is 'list'.
-	 *                       @see wp_list_categories()
-	 */
-	public function start_lvl( &$output, $depth = 0, $args = array() ) {
-		if ( 'list' != $args['style'] )
-			return;
-
-		$indent = str_repeat("\t", $depth);
-		$output .= "$indent<ul class='children'>\n";
-	}
-
-	/**
-	 * Ends the list of after the elements are added.
-	 *
-	 * @see Walker::end_lvl()
-	 *
-	 * @since 2.1.0
-	 *
-	 * @param string $output Passed by reference. Used to append additional content.
-	 * @param int    $depth  Depth of category. Used for tab indentation.
-	 * @param array  $args   An array of arguments. Will only append content if style argument value is 'list'.
-	 *                       @wsee wp_list_categories()
-	 */
-	public function end_lvl( &$output, $depth = 0, $args = array() ) {
-		if ( 'list' != $args['style'] )
-			return;
-
-		$indent = str_repeat("\t", $depth);
-		$output .= "$indent</ul>\n";
 	}
-
-	/**
-	 * Start the element output.
-	 *
-	 * @see Walker::start_el()
-	 *
-	 * @since 2.1.0
-	 *
-	 * @param string $output   Passed by reference. Used to append additional content.
-	 * @param object $category Category data object.
-	 * @param int    $depth    Depth of category in reference to parents. Default 0.
-	 * @param array  $args     An array of arguments. @see wp_list_categories()
-	 * @param int    $id       ID of the current category.
-	 */
-	public function start_el( &$output, $category, $depth = 0, $args = array(), $id = 0 ) {
-		/** This filter is documented in wp-includes/category-template.php */
-		$cat_name = apply_filters(
-			'list_cats',
-			esc_attr( $category->name ),
-			$category
-		);
-
-		// Don't generate an element if the category name is empty.
-		if ( ! $cat_name ) {
-			return;
-		}
-
-		$link = '<a href="' . esc_url( get_term_link( $category ) ) . '" ';
-		if ( $args['use_desc_for_title'] && ! empty( $category->description ) ) {
-			/**
-			 * Filter the category description for display.
-			 *
-			 * @since 1.2.0
-			 *
-			 * @param string $description Category description.
-			 * @param object $category    Category object.
-			 */
-			$link .= 'title="' . esc_attr( strip_tags( apply_filters( 'category_description', $category->description, $category ) ) ) . '"';
-		}
-
-		$link .= '>';
-		$link .= $cat_name . '</a>';
-
-		if ( ! empty( $args['feed_image'] ) || ! empty( $args['feed'] ) ) {
-			$link .= ' ';
-
-			if ( empty( $args['feed_image'] ) ) {
-				$link .= '(';
-			}
-
-			$link .= '<a href="' . esc_url( get_term_feed_link( $category->term_id, $category->taxonomy, $args['feed_type'] ) ) . '"';
-
-			if ( empty( $args['feed'] ) ) {
-				$alt = ' alt="' . sprintf(__( 'Feed for all posts filed under %s' ), $cat_name ) . '"';
-			} else {
-				$alt = ' alt="' . $args['feed'] . '"';
-				$name = $args['feed'];
-				$link .= empty( $args['title'] ) ? '' : $args['title'];
-			}
-
-			$link .= '>';
-
-			if ( empty( $args['feed_image'] ) ) {
-				$link .= $name;
-			} else {
-				$link .= "<img src='" . $args['feed_image'] . "'$alt" . ' />';
-			}
-			$link .= '</a>';
-
-			if ( empty( $args['feed_image'] ) ) {
-				$link .= ')';
-			}
-		}
-
-		if ( ! empty( $args['show_count'] ) ) {
-			$link .= ' (' . number_format_i18n( $category->count ) . ')';
-		}
-		if ( 'list' == $args['style'] ) {
-			$output .= "\t<li";
-			$css_classes = array(
-				'cat-item',
-				'cat-item-' . $category->term_id,
-			);
-
-			if ( ! empty( $args['current_category'] ) ) {
-				$_current_category = get_term( $args['current_category'], $category->taxonomy );
-				if ( $category->term_id == $args['current_category'] ) {
-					$css_classes[] = 'current-cat';
-				} elseif ( $category->term_id == $_current_category->parent ) {
-					$css_classes[] = 'current-cat-parent';
-				}
-			}
-
-			/**
-			 * Filter the list of CSS classes to include with each category in the list.
-			 *
-			 * @since 4.2.0
-			 *
-			 * @see wp_list_categories()
-			 *
-			 * @param array  $css_classes An array of CSS classes to be applied to each list item.
-			 * @param object $category    Category data object.
-			 * @param int    $depth       Depth of page, used for padding.
-			 * @param array  $args        An array of wp_list_categories() arguments.
-			 */
-			$css_classes = implode( ' ', apply_filters( 'category_css_class', $css_classes, $category, $depth, $args ) );
-
-			$output .=  ' class="' . $css_classes . '"';
-			$output .= ">$link\n";
-		} else {
-			$output .= "\t$link<br />\n";
-		}
-	}
-
-	/**
-	 * Ends the element output, if needed.
-	 *
-	 * @see Walker::end_el()
-	 *
-	 * @since 2.1.0
-	 *
-	 * @param string $output Passed by reference. Used to append additional content.
-	 * @param object $page   Not used.
-	 * @param int    $depth  Depth of category. Not used.
-	 * @param array  $args   An array of arguments. Only uses 'list' for whether should append to output. @see wp_list_categories()
-	 */
-	public function end_el( &$output, $page, $depth = 0, $args = array() ) {
-		if ( 'list' != $args['style'] )
-			return;
-
-		$output .= "</li>\n";
-	}
-
-}
-
-/**
- * Create HTML dropdown list of Categories.
- *
- * @package WordPress
- * @since 2.1.0
- * @uses Walker
- */
-class Walker_CategoryDropdown extends Walker {
-	/**
-	 * @see Walker::$tree_type
-	 * @since 2.1.0
-	 * @var string
-	 */
-	public $tree_type = 'category';
-
-	/**
-	 * @see Walker::$db_fields
-	 * @since 2.1.0
-	 * @todo Decouple this
-	 * @var array
-	 */
-	public $db_fields = array ('parent' => 'parent', 'id' => 'term_id');
-
-	/**
-	 * Start the element output.
-	 *
-	 * @see Walker::start_el()
-	 * @since 2.1.0
-	 *
-	 * @param string $output   Passed by reference. Used to append additional content.
-	 * @param object $category Category data object.
-	 * @param int    $depth    Depth of category. Used for padding.
-	 * @param array  $args     Uses 'selected', 'show_count', and 'value_field' keys, if they exist.
-	 *                         See {@see wp_dropdown_categories()}.
-	 */
-	public function start_el( &$output, $category, $depth = 0, $args = array(), $id = 0 ) {
-		$pad = str_repeat('&nbsp;', $depth * 3);
-
-		/** This filter is documented in wp-includes/category-template.php */
-		$cat_name = apply_filters( 'list_cats', $category->name, $category );
-
-		if ( ! isset( $args['value_field'] ) || ! isset( $category->{$args['value_field']} ) ) {
-			$args['value_field'] = 'term_id';
-		}
-
-		$output .= "\t<option class=\"level-$depth\" value=\"" . esc_attr( $category->{$args['value_field']} ) . "\"";
-
-		if ( $category->term_id == $args['selected'] )
-			$output .= ' selected="selected"';
-		$output .= '>';
-		$output .= $pad.$cat_name;
-		if ( $args['show_count'] )
-			$output .= '&nbsp;&nbsp;('. number_format_i18n( $category->count ) .')';
-		$output .= "</option>\n";
-	}
+	return call_user_func_array( array( $walker, 'walk' ), $args );
 }
 
 //
@@ -1174,15 +1065,7 @@
  * @return string Link on success, empty string if tag does not exist.
  */
 function get_tag_link( $tag ) {
-	if ( ! is_object( $tag ) )
-		$tag = (int) $tag;
-
-	$tag = get_term_link( $tag, 'post_tag' );
-
-	if ( is_wp_error( $tag ) )
-		return '';
-
-	return $tag;
+	return get_category_link( $tag );
 }
 
 /**
@@ -1191,12 +1074,12 @@
  * @since 2.3.0
  *
  * @param int $id Post ID.
- * @return array|bool Array of tag objects on success, false on failure.
+ * @return array|false|WP_Error Array of tag objects on success, false on failure.
  */
 function get_the_tags( $id = 0 ) {
 
 	/**
-	 * Filter the array of tags for the given post.
+	 * Filters the array of tags for the given post.
 	 *
 	 * @since 2.3.0
 	 *
@@ -1216,12 +1099,12 @@
  * @param string $sep Optional. Between tags.
  * @param string $after Optional. After tags.
  * @param int $id Optional. Post ID. Defaults to the current post.
- * @return string|bool|WP_Error A list of tags on success, false if there are no terms, WP_Error on failure.
+ * @return string|false|WP_Error A list of tags on success, false if there are no terms, WP_Error on failure.
  */
 function get_the_tag_list( $before = '', $sep = '', $after = '', $id = 0 ) {
 
 	/**
-	 * Filter the tags list for a given post.
+	 * Filters the tags list for a given post.
 	 *
 	 * @since 2.3.0
 	 *
@@ -1246,7 +1129,12 @@
 function the_tags( $before = null, $sep = ', ', $after = '' ) {
 	if ( null === $before )
 		$before = __('Tags: ');
-	echo get_the_tag_list($before, $sep, $after);
+
+	$the_tags = get_the_tag_list( $before, $sep, $after );
+
+	if ( ! is_wp_error( $the_tags ) ) {
+		echo $the_tags;
+	}
 }
 
 /**
@@ -1265,20 +1153,20 @@
  * Retrieve term description.
  *
  * @since 2.8.0
+ * @since 4.9.2 The `$taxonomy` parameter was deprecated.
  *
- * @param int $term Optional. Term ID. Will use global term ID by default.
- * @param string $taxonomy Optional taxonomy name. Defaults to 'post_tag'.
+ * @param int  $term       Optional. Term ID. Will use global term ID by default.
+ * @param null $deprecated Deprecated argument.
  * @return string Term description, available.
  */
-function term_description( $term = 0, $taxonomy = 'post_tag' ) {
+function term_description( $term = 0, $deprecated = null ) {
 	if ( ! $term && ( is_tax() || is_tag() || is_category() ) ) {
 		$term = get_queried_object();
 		if ( $term ) {
-			$taxonomy = $term->taxonomy;
 			$term = $term->term_id;
 		}
 	}
-	$description = get_term_field( 'description', $term, $taxonomy );
+	$description = get_term_field( 'description', $term );
 	return is_wp_error( $description ) ? '' : $description;
 }
 
@@ -1289,8 +1177,8 @@
  *
  * @param int|object $post Post ID or object.
  * @param string $taxonomy Taxonomy name.
- * @return array|bool|WP_Error Array of term objects on success, false if there are no terms
- *                             or the post does not exist, WP_Error on failure.
+ * @return array|false|WP_Error Array of WP_Term objects on success, false if there are no terms
+ *                              or the post does not exist, WP_Error on failure.
  */
 function get_the_terms( $post, $taxonomy ) {
 	if ( ! $post = get_post( $post ) )
@@ -1299,11 +1187,14 @@
 	$terms = get_object_term_cache( $post->ID, $taxonomy );
 	if ( false === $terms ) {
 		$terms = wp_get_object_terms( $post->ID, $taxonomy );
-		wp_cache_add($post->ID, $terms, $taxonomy . '_relationships');
+		if ( ! is_wp_error( $terms ) ) {
+			$term_ids = wp_list_pluck( $terms, 'term_id' );
+			wp_cache_add( $post->ID, $term_ids, $taxonomy . '_relationships' );
+		}
 	}
 
 	/**
-	 * Filter the list of terms attached to the given post.
+	 * Filters the list of terms attached to the given post.
 	 *
 	 * @since 3.1.0
 	 *
@@ -1329,7 +1220,7 @@
  * @param string $before Optional. Before list.
  * @param string $sep Optional. Separate items using this.
  * @param string $after Optional. After list.
- * @return string|bool|WP_Error A list of terms on success, false if there are no terms, WP_Error on failure.
+ * @return string|false|WP_Error A list of terms on success, false if there are no terms, WP_Error on failure.
  */
 function get_the_term_list( $id, $taxonomy, $before = '', $sep = '', $after = '' ) {
 	$terms = get_the_terms( $id, $taxonomy );
@@ -1351,7 +1242,7 @@
 	}
 
 	/**
-	 * Filter the term links for a given taxonomy.
+	 * Filters the term links for a given taxonomy.
 	 *
 	 * The dynamic portion of the filter name, `$taxonomy`, refers
 	 * to the taxonomy slug.
@@ -1360,12 +1251,77 @@
 	 *
 	 * @param array $links An array of term links.
 	 */
-	$term_links = apply_filters( "term_links-$taxonomy", $links );
+	$term_links = apply_filters( "term_links-{$taxonomy}", $links );
 
 	return $before . join( $sep, $term_links ) . $after;
 }
 
 /**
+ * Retrieve term parents with separator.
+ *
+ * @since 4.8.0
+ *
+ * @param int     $term_id  Term ID.
+ * @param string  $taxonomy Taxonomy name.
+ * @param string|array $args {
+ *     Array of optional arguments.
+ *
+ *     @type string $format    Use term names or slugs for display. Accepts 'name' or 'slug'.
+ *                             Default 'name'.
+ *     @type string $separator Separator for between the terms. Default '/'.
+ *     @type bool   $link      Whether to format as a link. Default true.
+ *     @type bool   $inclusive Include the term to get the parents for. Default true.
+ * }
+ * @return string|WP_Error A list of term parents on success, WP_Error or empty string on failure.
+ */
+function get_term_parents_list( $term_id, $taxonomy, $args = array() ) {
+	$list = '';
+	$term = get_term( $term_id, $taxonomy );
+
+	if ( is_wp_error( $term ) ) {
+		return $term;
+	}
+
+	if ( ! $term ) {
+		return $list;
+	}
+
+	$term_id = $term->term_id;
+
+	$defaults = array(
+		'format'    => 'name',
+		'separator' => '/',
+		'link'      => true,
+		'inclusive' => true,
+	);
+
+	$args = wp_parse_args( $args, $defaults );
+
+	foreach ( array( 'link', 'inclusive' ) as $bool ) {
+		$args[ $bool ] = wp_validate_boolean( $args[ $bool ] );
+	}
+
+	$parents = get_ancestors( $term_id, $taxonomy, 'taxonomy' );
+
+	if ( $args['inclusive'] ) {
+		array_unshift( $parents, $term_id );
+	}
+
+	foreach ( array_reverse( $parents ) as $term_id ) {
+		$parent = get_term( $term_id, $taxonomy );
+		$name   = ( 'slug' === $args['format'] ) ? $parent->slug : $parent->name;
+
+		if ( $args['link'] ) {
+			$list .= '<a href="' . esc_url( get_term_link( $parent->term_id, $taxonomy ) ) . '">' . $name . '</a>' . $args['separator'];
+		} else {
+			$list .= $name . $args['separator'];
+		}
+	}
+
+	return $list;
+}
+
+/**
  * Display the terms in a list.
  *
  * @since 2.5.0
@@ -1375,7 +1331,7 @@
  * @param string $before Optional. Before list.
  * @param string $sep Optional. Separate items using this.
  * @param string $after Optional. After list.
- * @return false|null False on WordPress error. Returns null when displaying.
+ * @return false|void False on WordPress error.
  */
 function the_terms( $id, $taxonomy, $before = '', $sep = ', ', $after = '' ) {
 	$term_list = get_the_term_list( $id, $taxonomy, $before, $sep, $after );
@@ -1384,7 +1340,7 @@
 		return false;
 
 	/**
-	 * Filter the list of terms to display.
+	 * Filters the list of terms to display.
 	 *
 	 * @since 2.9.0
 	 *