Date/Time: Correct sanitization of timezone_string in sanitize_option().

This fixes a bug where if the `timezone_string` is set to a timezone name which has since been deprecated, the option value would be “lost” when saving the value again, as the comparison being done to verify whether it is a valid timezone name would only take “current” timezone names into account and would invalidate deprecated timezone names.

By passing the `DateTimeZone::ALL_WITH_BC` constant as the `$timezoneGroup` parameter to the PHP native `timezone_identifiers_list()` function, a timezone name list is retrieved containing both current and deprecated timezone names, preventing the invalidation of the option value.

See the extensive write-up about this in ticket #56468.

Also see: [https://www.php.net/manual/en/datetimezone.listidentifiers.php PHP Manual: timezone_identifiers_list()].

Includes adding a dedicated test to the data provider used in the `Tests_Option_SanitizeOption` test class.

Note: The new data set is ''named'', even though the other data sets are unnamed, to make sure it is clear what this data set is testing. Adding test names for the original data sets in this data provider would be a great future improvement, but is outside of the scope of this commit.

Follow-up to [18323], [33119], [54207], [54217], [54227].

Props jrf, costdev.
See #56468.

git-svn-id: https://develop.svn.wordpress.org/trunk@54229 602fd350-edb4-49c9-b593-d223f7449a82

Author: SergeyBiryukov

src/wp-includes/formatting.php

@@ -4923,7 +4923,7 @@ function sanitize_option( $option, $value ) {
 			break;
 
 		case 'timezone_string':
-			$allowed_zones = timezone_identifiers_list();
+			$allowed_zones = timezone_identifiers_list( DateTimeZone::ALL_WITH_BC );
 			if ( ! in_array( $value, $allowed_zones, true ) && ! empty( $value ) ) {
 				$error = __( 'The timezone you have entered is not valid. Please select a valid timezone.' );
 			}

tests/phpunit/tests/option/sanitizeOption.php

@@ -69,6 +69,12 @@ public function sanitize_option_provider() {
 			array( 'timezone_string', 0, 0 ),
 			array( 'timezone_string', 'Europe/London', 'Europe/London' ),
 			array( 'timezone_string', get_option( 'timezone_string' ), 'invalid' ),
+			// @ticket 56468
+			'deprecated timezone string is accepted as valid' => array(
+				'option_name' => 'timezone_string',
+				'sanitized'   => 'America/Buenos_Aires',
+				'original'    => 'America/Buenos_Aires',
+			),
 			array( 'permalink_structure', '', '' ),
 			array( 'permalink_structure', '/%year%/%20%postname%', '/%year%/ %postname%' ),
 			array( 'default_role', 'subscriber', 'subscriber' ),