Ticket #4575: 4575.diff

wp-includes/feed-rss2.php

@@ -42 +42 @@
         <atom:link href="<?php self_link(); ?>" rel="self" type="application/rss+xml" />
         <link><?php bloginfo_rss('url') ?></link>
         <description><?php bloginfo_rss("description") ?></description>
-        <lastBuildDate><?php echo mysql2date('D, d M Y H:i:s +0000', get_lastpostmodified('GMT'), false); ?></lastBuildDate>
+        <lastBuildDate><?php echo mysql2date('D, d M Y H:i:s +0000', get_last_build_date_feed(), false); ?></lastBuildDate>
         <language><?php bloginfo_rss( 'language' ); ?></language>
         <sy:updatePeriod><?php
                 $duration = 'hourly';

wp-includes/feed.php

@@ -88 +88 @@
 }
 
 /**
+ * Get the timestamp of the most recently modified post from WP_Query
+ *
+ * If viewing a comment feed, the date of the most recently modified
+ * comment will be returned.
+ *
+ * @since 4.3.0
+ *
+ * @return string Date ('Y-m-d H:i:s' for use with mysql2date() )
+ */
+function get_last_build_date_feed() {
+        global $wp_query, $wpdb;
+
+        if ( $wp_query->have_posts() ) {
+                $post_ids = array();
+                foreach( $wp_query->posts as $post ) {
+                        $post_ids[] = $post->ID;
+                }
+                $postids = implode( "','", $post_ids );
+
+                $max_post_time = $wpdb->get_var( $wpdb->prepare( "SELECT MAX($wpdb->posts.post_modified_gmt) FROM $wpdb->posts WHERE $wpdb->posts.ID IN ('%s')", $postids ) );
+
+                if( $wp_query->is_comment_feed() ) {
+                        $max_comment_time = $wpdb->get_var( $wpdb->prepare( "SELECT MAX($wpdb->comments.comment_date_gmt) FROM $wpdb->comments WHERE $wpdb->comments.comment_post_ID IN ('%s')", $postids ) );
+                        return max( $max_post_time, $max_comment_time );
+                }
+                return $max_post_time;
+        }
+
+        // Fallback to last time any post was modified or published.
+        return get_lastpostmodified( 'GMT' );
+}
+
+/**
  * Retrieve the blog title for the feed title.
  *
  * @since 2.2.0