Ticket #18660: link-template.php.2.diff

wp-includes/link-template.php

@@ -2355 +2355 @@
 }
 
 /**
- * Output rel=canonical for singular queries
+ * Output rel=canonical for home, singular, author archives, and taxonomy archives.
  *
  * @package WordPress
  * @since 2.9.0
 */
 function rel_canonical() {
-        if ( !is_singular() )
-                return;
+        
+        global $wp_query;
+        
+        /** Get the object ID */
+        $id = $wp_query->get_queried_object_id();
 
-        global $wp_the_query;
-        if ( !$id = $wp_the_query->get_queried_object_id() )
+        $canonical = '';
+
+        if ( is_front_page() ) {
+                $canonical = trailingslashit( home_url() );
+        }
+
+        if ( is_singular() ) {
+                $canonical = get_permalink( absint( $id ) );
+        }
+
+        if ( is_category() || is_tag() || is_tax() ) {
+                $canonical = get_term_link( absint( $id ), $wp_query->queried_object->taxonomy );
+        }
+
+        if ( is_author() ) {
+                $canonical = get_author_posts_url( absint( $id ) );
+        }
+        
+        $canonical = apply_filters( 'rel_canonical', $canonical, $id );
+
+        /** If empty, return nothing */
+        if ( ! $canonical )
                 return;
 
-        $link = get_permalink( $id );
-        echo "<link rel='canonical' href='$link' />\n";
+        printf( '<link rel="canonical" href="%s" />' . "\n", esc_url( $canonical ) );
+
 }
 
 /**