From eae1462bef6f5b05a3ab87edcfc9a2faef292446 Mon Sep 17 00:00:00 2001
From: Sergey Biryukov <sergeybiryukov.ru@gmail.com>
Date: Thu, 30 Apr 2020 12:05:14 +0000
Subject: [PATCH] Canonical: Redirect paged requests for non-paginated posts to
 the post permalink.

This avoids displaying duplicate content of the same post under different URLs and ensures the canonical URL is correct.

Previously, requests for invalid page numbers were only redirected to the post permalink if the post was actually paginated using the `<!--nextpage-->` marker.

Follow-up to [34492].

Props jeremyfelt, prografika, sachit.tandukar, subrataemfluence, hronak, ekatherine, henry.wright, chesio, dd32, SergeyBiryukov.
Fixes #40773. See #45337, #28081, #11694.
Built from https://develop.svn.wordpress.org/trunk@47727


git-svn-id: http://core.svn.wordpress.org/trunk@47504 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/canonical.php |  3 +--
 wp-includes/class-wp.php  | 11 ++++++++---
 wp-includes/version.php   |  2 +-
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/wp-includes/canonical.php b/wp-includes/canonical.php
index 85ffa7d93c..fd6676724d 100644
--- a/wp-includes/canonical.php
+++ b/wp-includes/canonical.php
@@ -157,8 +157,7 @@ function redirect_canonical( $requested_url = null, $do_redirect = true ) {
 			}
 		}
 
-		if ( get_query_var( 'page' ) && $wp_query->post &&
-			false !== strpos( $wp_query->post->post_content, '<!--nextpage-->' ) ) {
+		if ( get_query_var( 'page' ) && $wp_query->post ) {
 			$redirect['path']  = rtrim( $redirect['path'], (int) get_query_var( 'page' ) . '/' );
 			$redirect['query'] = remove_query_arg( 'page', $redirect['query'] );
 			$redirect_url      = get_permalink( $wp_query->post->ID );
diff --git a/wp-includes/class-wp.php b/wp-includes/class-wp.php
index 783a993cdc..e5dadcd232 100644
--- a/wp-includes/class-wp.php
+++ b/wp-includes/class-wp.php
@@ -678,9 +678,14 @@ class WP {
 
 				// Check for paged content that exceeds the max number of pages.
 				$next = '<!--nextpage-->';
-				if ( $p && false !== strpos( $p->post_content, $next ) && ! empty( $this->query_vars['page'] ) ) {
-					$page    = trim( $this->query_vars['page'], '/' );
-					$success = (int) $page <= ( substr_count( $p->post_content, $next ) + 1 );
+				if ( $p && ! empty( $this->query_vars['page'] ) ) {
+					// Check if content is actually intended to be paged.
+					if ( false !== strpos( $p->post_content, $next ) ) {
+						$page    = trim( $this->query_vars['page'], '/' );
+						$success = (int) $page <= ( substr_count( $p->post_content, $next ) + 1 );
+					} else {
+						$success = false;
+					}
 				}
 			}
 
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 98018b4896..61d02e2fa6 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.5-alpha-47706';
+$wp_version = '5.5-alpha-47727';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.