Taxonomy: Introduce the dynamic `taxonomy_labels_{$taxonomy}` filter, which can be used to manipulate the labels for a given taxonomy.

The addition of this hook brings parity with the earlier-introduced `post_type_labels_{$post_type}` filter, which allows for similarly manipulating labels for a given post type.

Note: It isn't possible to unset or remove default labels via either of these hooks, only to overwrite. This is because WordPress relies on defaults being set for use in various UIs and admin experiences.

Props flixos90.
Fixes #34554.

Built from https://develop.svn.wordpress.org/trunk@35504


git-svn-id: http://core.svn.wordpress.org/trunk@35468 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/taxonomy-functions.php

@@ -540,7 +540,29 @@ function get_taxonomy_labels( $tax ) {
 	);
 	$nohier_vs_hier_defaults['menu_name'] = $nohier_vs_hier_defaults['name'];
 
-	return _get_custom_object_labels( $tax, $nohier_vs_hier_defaults );
+	$labels = _get_custom_object_labels( $tax, $nohier_vs_hier_defaults );
+
+	$taxonomy = $tax->name;
+
+	$default_labels = clone $labels;
+
+	/**
+	 * Filter the labels of a specific taxonomy.
+	 *
+	 * The dynamic portion of the hook name, `$taxonomy`, refers to the taxonomy slug.
+	 *
+	 * @since 4.4.0
+	 *
+	 * @see get_taxonomy_labels() for the full list of taxonomy labels.
+	 *
+	 * @param object $labels Object with labels for the taxonomy as member variables.
+	 */
+	$labels = apply_filters( "taxonomy_labels_{$taxonomy}", $labels );
+
+	// Ensure that the filtered labels contain all required default values.
+	$labels = (object) array_merge( (array) $default_labels, (array) $labels );
+
+	return $labels;
 }
 
 /**

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.4-beta2-35503';
+$wp_version = '4.4-beta2-35504';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.