Comments: Noindex pages containing unapproved comments.

Adds a `noindex` directive to pages displaying a preview of an unapproved comment, ie pages with both an `approved` and `moderation-hash` parameter.

This is to prevent the pages from appearing in search engines which can be the case if they ignore the canonical URL directive.

Props peterwilsoncc, flixos90, joostdevalk.
Fixes #62760.


git-svn-id: https://develop.svn.wordpress.org/trunk@59576 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/default-filters.php

@@ -366,7 +366,13 @@ add_action( 'after_switch_theme', '_wp_sidebars_changed' );
 add_action( 'wp_enqueue_scripts', 'wp_enqueue_emoji_styles' );
 add_action( 'wp_print_styles', 'print_emoji_styles' ); // Retained for backwards-compatibility. Unhooked by wp_enqueue_emoji_styles().
 
-if ( isset( $_GET['replytocom'] ) ) {
+if (
+	// Comment reply link.
+	isset( $_GET['replytocom'] )
+	||
+	// Unapproved comment preview.
+	( isset( $_GET['unapproved'] ) && isset( $_GET['moderation-hash'] ) )
+) {
 	add_filter( 'wp_robots', 'wp_robots_no_robots' );
 }