I18N: Add ability to change user's locale back to site's locale.

Previously there was no way to remove the user locale setting again, even though that might be desirable.

This adds a new 'Site Default' option to the user-specific language setting by introducing a new `show_site_locale_default` argument to `wp_dropdown_languages()`.

Props ocean90.
See #29783.
Fixes #38632.
Built from https://develop.svn.wordpress.org/trunk@39169


git-svn-id: http://core.svn.wordpress.org/trunk@39109 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/user.php

@@ -98,11 +98,13 @@ function edit_user( $user_id = 0 ) {
 
 		if ( isset( $_POST['locale'] ) ) {
 			$locale = sanitize_text_field( $_POST['locale'] );
-			if ( ! in_array( $locale, get_available_languages(), true ) ) {
+			if ( 'site-default' === $locale ) {
 				$locale = '';
+			} elseif ( ! in_array( $locale, get_available_languages(), true ) ) {
+				$locale = 'en_US';
 			}
 
-			$user->locale = ( '' === $locale ) ? 'en_US' : $locale;
+			$user->locale = $locale;
 		}
 	}
 

wp-admin/user-edit.php

@@ -284,9 +284,9 @@ if ( $languages ) : ?>
 		$user_locale = $profileuser->locale;
 
 		if ( 'en_US' === $user_locale ) {
-			$user_locale = false;
+			$user_locale = '';
-		} elseif ( ! in_array( $user_locale, $languages, true ) ) {
+		} elseif ( '' === $user_locale || ! in_array( $user_locale, $languages, true ) ) {
-			$user_locale = get_locale();
+			$user_locale = 'site-default';
 		}
 
 		wp_dropdown_languages( array(
@@ -294,7 +294,8 @@ if ( $languages ) : ?>
 			'id'                          => 'locale',
 			'selected'                    => $user_locale,
 			'languages'                   => $languages,
-			'show_available_translations' => false
+			'show_available_translations' => false,
+			'show_site_locale_default'    => true
 		) );
 		?>
 	</td>

wp-includes/l10n.php

@@ -1048,6 +1048,7 @@ function wp_get_pomo_file_data( $po_file ) {
  *
  * @since 4.0.0
  * @since 4.3.0 Introduced the `echo` argument.
+ * @since 4.7.0 Introduced the `show_site_locale_default` argument.
  *
  * @see get_available_languages()
  * @see wp_get_available_translations()
@@ -1065,6 +1066,7 @@ function wp_get_pomo_file_data( $po_file ) {
  *     @type bool|int $echo                         Whether to echo the generated markup. Accepts 0, 1, or their
  *                                                  boolean equivalents. Default 1.
  *     @type bool     $show_available_translations  Whether to show available translations. Default true.
+ *     @type bool     $show_site_locale_default     Whether to show an option to fall back to the site's locale. Default false.
  * }
  * @return string HTML content
  */
@@ -1078,8 +1080,14 @@ function wp_dropdown_languages( $args = array() ) {
 		'selected'     => '',
 		'echo'         => 1,
 		'show_available_translations' => true,
+		'show_site_locale_default'    => false,
 	) );
 
+	// English (United States) uses an empty string for the value attribute.
+	if ( 'en_US' === $args['selected'] ) {
+		$args['selected'] = '';
+	}
+
 	$translations = $args['translations'];
 	if ( empty( $translations ) ) {
 		require_once( ABSPATH . 'wp-admin/includes/translation-install.php' );
@@ -1122,7 +1130,20 @@ function wp_dropdown_languages( $args = array() ) {
 	if ( $translations_available ) {
 		$structure[] = '<optgroup label="' . esc_attr_x( 'Installed', 'translations' ) . '">';
 	}
-	$structure[] = '<option value="" lang="en" data-installed="1">English (United States)</option>';
+
+	if ( $args['show_site_locale_default'] ) {
+		$structure[] = sprintf(
+			'<option value="site-default" data-installed="1"%s>%s</option>',
+			selected( 'site-default', $args['selected'], false ),
+			_x( 'Site Default', 'default site language' )
+		);
+	}
+
+	$structure[] = sprintf(
+		'<option value="" lang="en" data-installed="1"%s>English (United States)</option>',
+		selected( '', $args['selected'], false )
+	);
+
 	foreach ( $languages as $language ) {
 		$structure[] = sprintf(
 			'<option value="%s" lang="%s"%s data-installed="1">%s</option>',

wp-includes/rest-api/endpoints/class-wp-rest-users-controller.php

@@ -1074,7 +1074,7 @@ class WP_REST_Users_Controller extends WP_REST_Controller {
 				'locale'    => array(
 					'description' => __( 'Locale for the resource.' ),
 					'type'        => 'string',
-					'enum'        => array_merge( array( 'en_US' ), get_available_languages() ),
+					'enum'        => array_merge( array( '', 'en_US' ), get_available_languages() ),
 					'context'     => array( 'edit' ),
 				),
 				'nickname'    => array(

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.7-beta2-39168';
+$wp_version = '4.7-beta2-39169';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.