From 72fda0359f30d0f81a89e3ab369b1389b4cf2fb1 Mon Sep 17 00:00:00 2001
From: Pascal Birchler <pascal.birchler@gmail.com>
Date: Fri, 23 Jun 2023 16:03:25 +0000
Subject: [PATCH] I18N: Ensure `determine_locale()` does not potentially return
 an empty string.

Call `get_locale()` as a last resort in case the sanitized locale is an empty string.

Also swaps conditionals to cater for more typical use case and adds tests.

Follow-up to [55862]

Props Cybr, swissspidy.
Fixes #58317.
Built from https://develop.svn.wordpress.org/trunk@56003


git-svn-id: http://core.svn.wordpress.org/trunk@55515 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/l10n.php    | 10 ++++++----
 wp-includes/version.php |  2 +-
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/wp-includes/l10n.php b/wp-includes/l10n.php
index 8444bf2c82..951c1c316b 100644
--- a/wp-includes/l10n.php
+++ b/wp-includes/l10n.php
@@ -145,12 +145,14 @@ function determine_locale() {
 		} else {
 			$determined_locale = sanitize_locale_name( $_COOKIE['wp_lang'] );
 		}
-	} else if (
-		( isset( $_GET['_locale'] ) && 'user' === $_GET['_locale'] && wp_is_json_request() ) ||
-		is_admin()
+	} elseif (
+		is_admin() ||
+		( isset( $_GET['_locale'] ) && 'user' === $_GET['_locale'] && wp_is_json_request() )
 	) {
 		$determined_locale = get_user_locale();
-	} else {
+	}
+
+	if ( ! $determined_locale ) {
 		$determined_locale = get_locale();
 	}
 
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 0d805bb429..09f10ce4c6 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.3-alpha-56002';
+$wp_version = '6.3-alpha-56003';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.