From e53ffbaf955beb449c9ecd22c3ba3d9a25030553 Mon Sep 17 00:00:00 2001
From: Sergey Biryukov <sergeybiryukov.ru@gmail.com>
Date: Mon, 23 Aug 2021 11:44:01 +0000
Subject: [PATCH] Code Modernization: Pass correct default value to
 `http_build_query()` in `WP_Sitemaps_Provider::get_sitemap_url()`.

The `WP_Sitemaps_Provider::get_sitemap_url()` method calls the PHP native `http_build_query()` function, the second parameter of which is the ''optional'' `$numeric_prefix` parameter which expects a `string`.

A parameter being optional, however, does not automatically make it nullable.

As of PHP 8.1, passing `null` to a non-nullable PHP native function will generate a deprecation notice.

In this case, this function call yielded a `http_build_query(): Passing null to parameter #2 ($numeric_prefix) of type string is deprecated` notice.

Changing the `null` to an empty string fixes this without a backward compatibility break.

This change is already covered by tests as 14 of the existing tests failed on these function calls when running the tests on PHP 8.1.

References:
* [https://www.php.net/manual/en/function.http-build-query.php PHP Manual: http_build_query()]
* [https://wiki.php.net/rfc/deprecate_null_to_scalar_internal_arg PHP RFC: Deprecate passing null to non-nullable arguments of internal functions]

Follow-up to [48470].

Props jrf.
See #53635.
Built from https://develop.svn.wordpress.org/trunk@51652


git-svn-id: http://core.svn.wordpress.org/trunk@51258 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/sitemaps/class-wp-sitemaps-provider.php | 2 +-
 wp-includes/version.php                             | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/wp-includes/sitemaps/class-wp-sitemaps-provider.php b/wp-includes/sitemaps/class-wp-sitemaps-provider.php
index 3440f62b34..e77681d721 100644
--- a/wp-includes/sitemaps/class-wp-sitemaps-provider.php
+++ b/wp-includes/sitemaps/class-wp-sitemaps-provider.php
@@ -160,7 +160,7 @@ abstract class WP_Sitemaps_Provider {
 		);
 
 		if ( ! $wp_rewrite->using_permalinks() ) {
-			$basename = '/?' . http_build_query( $params, null, '&' );
+			$basename = '/?' . http_build_query( $params, '', '&' );
 		}
 
 		return home_url( $basename );
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 68c87cfe7f..b670481167 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.9-alpha-51651';
+$wp_version = '5.9-alpha-51652';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.