From 12f4c30551505a88689a7578a52225b2662294a1 Mon Sep 17 00:00:00 2001
From: Scott Taylor <wonderboymusic@git.wordpress.org>
Date: Fri, 4 Dec 2015 23:10:09 +0000
Subject: [PATCH] Canonical: introduce `strip_fragment_from_url()` and use when
 comparing URLs in `redirect_canonical()`.

Props tellyworth.
Fixes #19918.


git-svn-id: https://develop.svn.wordpress.org/trunk@35770 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/canonical.php | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/src/wp-includes/canonical.php b/src/wp-includes/canonical.php
index 84b90e279e..cacbdaadfe 100644
--- a/src/wp-includes/canonical.php
+++ b/src/wp-includes/canonical.php
@@ -489,7 +489,7 @@ function redirect_canonical( $requested_url = null, $do_redirect = true ) {
 	$redirect_url = apply_filters( 'redirect_canonical', $redirect_url, $requested_url );
 
 	// yes, again -- in case the filter aborted the request
-	if ( ! $redirect_url || $redirect_url == $requested_url ) {
+	if ( ! $redirect_url || strip_fragment_from_url( $redirect_url ) == strip_fragment_from_url( $requested_url ) ) {
 		return;
 	}
 
@@ -534,6 +534,31 @@ function _remove_qs_args_if_not_in_url( $query_string, Array $args_to_check, $ur
 	return $query_string;
 }
 
+/**
+ * Strips the #fragment from a URL, if one is present.
+ *
+ * @since 4.4.0
+ *
+ * @param string $url The URL to strip.
+ * @return string The altered URL.
+ */
+function strip_fragment_from_url( $url ) {
+	$parsed_url = @parse_url( $url );
+	if ( ! empty( $parsed_url['host'] ) ) {
+		// This mirrors code in redirect_canonical(). It does not handle every case.
+		$url = $parsed_url['scheme'] . '://' . $parsed_url['host'];
+		if ( ! empty( $parsed_url['port'] ) ) {
+			$url .= ':' . $parsed_url['port'];
+		}
+		$url .= $parsed_url['path'];
+		if ( ! empty( $parsed_url['query'] ) ) {
+			$url .= '?' . $parsed_url['query'];
+		}
+	}
+
+	return $url;
+}
+
 /**
  * Attempts to guess the correct URL based on query vars
  *