From b0aad156bbac2c334bd1ac60ca13a8c6283e4c2a Mon Sep 17 00:00:00 2001
From: Pascal Birchler <swissspidy@git.wordpress.org>
Date: Tue, 1 Nov 2016 09:15:42 +0000
Subject: [PATCH] I18N: Show available timezones in the user's locale on the
 settings screen.

Adds a `$locale` parameter to `wp_timezone_choice()` to only reload translations when necessary.

Props yale01.
See #38485.

git-svn-id: https://develop.svn.wordpress.org/trunk@39068 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-admin/options-general.php |  2 +-
 src/wp-includes/functions.php    | 16 ++++++++++------
 2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/src/wp-admin/options-general.php b/src/wp-admin/options-general.php
index 7b1c999277..22d475c2e2 100644
--- a/src/wp-admin/options-general.php
+++ b/src/wp-admin/options-general.php
@@ -147,7 +147,7 @@ if ( empty($tzstring) ) { // Create a UTC+- zone if no timezone string exists
 <td>
 
 <select id="timezone_string" name="timezone_string" aria-describedby="timezone-description">
-<?php echo wp_timezone_choice($tzstring); ?>
+	<?php echo wp_timezone_choice( $tzstring, get_user_locale() ); ?>
 </select>
 
 <p class="description" id="timezone-description"><?php _e( 'Choose either a city in the same timezone as you or a UTC timezone offset.' ); ?></p>
diff --git a/src/wp-includes/functions.php b/src/wp-includes/functions.php
index ff489ae869..32fa55c9df 100644
--- a/src/wp-includes/functions.php
+++ b/src/wp-includes/functions.php
@@ -4501,21 +4501,25 @@ function _wp_timezone_choice_usort_callback( $a, $b ) {
  * Gives a nicely-formatted list of timezone strings.
  *
  * @since 2.9.0
+ * @since 4.7.0 Added the `$locale` parameter.
  *
  * @staticvar bool $mo_loaded
+ * @staticvar string $locale_loaded
  *
  * @param string $selected_zone Selected timezone.
+ * @param string $locale        Optional. Locale to load the timezones in. Default current site locale.
  * @return string
  */
-function wp_timezone_choice( $selected_zone ) {
-	static $mo_loaded = false;
+function wp_timezone_choice( $selected_zone, $locale = null ) {
+	static $mo_loaded = false, $locale_loaded = null;
 
 	$continents = array( 'Africa', 'America', 'Antarctica', 'Arctic', 'Asia', 'Atlantic', 'Australia', 'Europe', 'Indian', 'Pacific');
 
-	// Load translations for continents and cities
-	if ( !$mo_loaded ) {
-		$locale = get_locale();
-		$mofile = WP_LANG_DIR . '/continents-cities-' . $locale . '.mo';
+	// Load translations for continents and cities.
+	if ( ! $mo_loaded || $locale !== $locale_loaded ) {
+		$locale_loaded = $locale ? $locale : get_locale();
+		$mofile = WP_LANG_DIR . '/continents-cities-' . $locale_loaded . '.mo';
+		unload_textdomain( 'continents-cities' );
 		load_textdomain( 'continents-cities', $mofile );
 		$mo_loaded = true;
 	}