Ticket #56068: 56068.2.diff

src/wp-includes/class-wp.php

@@ -407 +407 @@
          * If showing a feed, it will also send Last-Modified, ETag, and 304 status if needed.
          *
          * @since 2.0.0
-         * @since 4.4.0 `X-Pingback` header is added conditionally after posts have been queried in handle_404().
+         * @since 4.4.0 `X-Pingback` header is added conditionally for single posts that allow pings.
+         * @since 6.1.0 Runs after posts have been queried.
          */
         public function send_headers() {
                 $headers       = array();
@@ -503 +504 @@
                         }
                 }
 
+                if ( is_singular() ) {
+                        $post = isset( $wp_query->post ) ? $wp_query->post : null;
+
+                        // Only set X-Pingback for single posts that allow pings.
+                        if ( $post && pings_open( $post ) ) {
+                                $headers['X-Pingback'] = get_bloginfo( 'pingback_url', 'display' );
+                        }
+                }
+
                 /**
                  * Filters the HTTP headers before they're sent to the browser.
                  *
@@ -700 +710 @@
 
                         if ( is_singular() ) {
                                 $post = isset( $wp_query->post ) ? $wp_query->post : null;
+                                $next = '<!--nextpage-->';
 
-                                // Only set X-Pingback for single posts that allow pings.
-                                if ( $post && pings_open( $post ) && ! headers_sent() ) {
-                                        header( 'X-Pingback: ' . get_bloginfo( 'pingback_url', 'display' ) );
-                                }
-
                                 // Check for paged content that exceeds the max number of pages.
-                                $next = '<!--nextpage-->';
                                 if ( $post && ! empty( $this->query_vars['page'] ) ) {
                                         // Check if content is actually intended to be paged.
                                         if ( false !== strpos( $post->post_content, $next ) ) {
@@ -769 +774 @@
 
                 $parsed = $this->parse_request( $query_args );
 
-                $this->send_headers();
-
                 if ( $parsed ) {
                         $this->query_posts();
                         $this->handle_404();
@@ -777 +780 @@
                         $this->register_globals();
                 }
 
+                $this->send_headers();
+
                 /**
                  * Fires once the WordPress environment has been set up.
                  *