Ticket #4575: 4575.9.diff

src/wp-includes/feed-atom-comments.php

@@ -42 +42 @@
         <subtitle type="text"><?php bloginfo_rss('description'); ?></subtitle>
 
         <updated><?php
-                $date = get_lastcommentmodified( 'GMT' );
+                $date = get_last_build_date();
                 echo $date ? mysql2date( 'Y-m-d\TH:i:s\Z', $date, false ) : date( 'Y-m-d\TH:i:s\Z' );
         ?></updated>
 

src/wp-includes/feed-atom.php

@@ -31 +31 @@
         <subtitle type="text"><?php bloginfo_rss("description") ?></subtitle>
 
         <updated><?php
-                $date = get_lastpostmodified( 'GMT' );
+                $date = get_last_build_date();
                 echo $date ? mysql2date( 'Y-m-d\TH:i:s\Z', $date, false ) : date( 'Y-m-d\TH:i:s\Z' );
         ?></updated>
 

src/wp-includes/feed-rss2-comments.php

@@ -48 +48 @@
         <link><?php (is_single()) ? the_permalink_rss() : bloginfo_rss("url") ?></link>
         <description><?php bloginfo_rss("description") ?></description>
         <lastBuildDate><?php
-                $date = get_lastcommentmodified( 'GMT' );
+                $date = get_last_build_date();
                 echo $date ? mysql2date( 'r', $date, false ) : date( 'r' );
         ?></lastBuildDate>
         <sy:updatePeriod><?php

src/wp-includes/feed-rss2.php

@@ -43 +43 @@
         <link><?php bloginfo_rss('url') ?></link>
         <description><?php bloginfo_rss("description") ?></description>
         <lastBuildDate><?php
-                $date = get_lastpostmodified( 'GMT' );
+                $date = get_last_build_date();
                 echo $date ? mysql2date( 'r', $date, false ) : date( 'r' );
         ?></lastBuildDate>
         <language><?php bloginfo_rss( 'language' ); ?></language>

src/wp-includes/feed.php

@@ -89 +89 @@
 }
 
 /**
+ * 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 4.8.1
+ *
+ * @return string Date ('Y-m-d H:i:s' for use with mysql2date() )
+ */
+function get_last_build_date() {
+        global $wp_query;
+
+        if ( $wp_query->have_posts() ) {
+                // Determine max post time
+                $post_times = wp_list_pluck( $wp_query->posts, 'post_modified_gmt' );
+                $max_post_time = max( $post_times );
+
+                // If this is a comment feed, check those objects too
+                if ( $wp_query->is_comment_feed() && $wp_query->have_comments() ) {
+                        // Determine the max comment time
+                        $comment_times = wp_list_pluck( $wp_query->comments, 'comment_date_gmt' );
+                        $max_comment_time = max( $comment_times );
+
+                        // Return the most recent timestamp between posts and comments
+                        return max( $max_post_time, $max_comment_time );
+                }
+                // Return the most recent post timestamp if there are no comments to consider
+                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