General: Improve resilience of feed_links_extra() when global $post is not set.

This obtains the global post via `get_queried_object()` when `is_singular()`.

Developed in #10401

Props westonruter, johnjamesjacoby, Presskopp, abcd95, dilipbheda, sabernhardt, awetz583, indirabiswas27.
Fixes #63263.


git-svn-id: https://develop.svn.wordpress.org/trunk@61056 602fd350-edb4-49c9-b593-d223f7449a82

Author: westonruter

src/wp-includes/general-template.php

@@ -3326,9 +3326,9 @@ function feed_links_extra( $args = array() ) {
 	 */
 	$args = apply_filters( 'feed_links_extra_args', $args );
 
-	if ( is_singular() ) {
-		$id   = 0;
-		$post = get_post( $id );
+	$queried_object = get_queried_object();
+	if ( is_singular() && $queried_object instanceof WP_Post ) {
+		$post = $queried_object;
 
 		/** This filter is documented in wp-includes/general-template.php */
 		$show_comments_feed = apply_filters( 'feed_links_show_comments_feed', true );
@@ -3348,12 +3348,17 @@ function feed_links_extra( $args = array() ) {
 		 */
 		$show_post_comments_feed = apply_filters( 'feed_links_extra_show_post_comments_feed', $show_comments_feed );
 
-		if ( $show_post_comments_feed && ( comments_open() || pings_open() || $post->comment_count > 0 ) ) {
+		if ( $show_post_comments_feed && ( comments_open( $post ) || pings_open( $post ) || (int) $post->comment_count > 0 ) ) {
 			$title = sprintf(
 				$args['singletitle'],
 				get_bloginfo( 'name' ),
 				$args['separator'],
-				the_title_attribute( array( 'echo' => false ) )
+				the_title_attribute(
+					array(
+						'echo' => false,
+						'post' => $post,
+					)
+				)
 			);
 
 			$feed_link = get_post_comments_feed_link( $post->ID );

tests/phpunit/tests/general/feedLinksExtra.php

@@ -634,4 +634,15 @@ public function data_feed_links_extra_should_output_nothing_when_filters_return_
 			),
 		);
 	}
+
+	/**
+	 * @ticket 63263
+	 */
+	public function test_feed_links_extra_should_work_fail_if_global_post_empty() {
+		$post_id = self::factory()->post->create();
+		$this->go_to( get_permalink( $post_id ) );
+		$GLOBALS['post'] = null;
+
+		$this->assertNotEmpty( get_echo( 'feed_links_extra' ) );
+	}
 }