From 7670b7dca84fccc40ec4c3271075046dfc2f6f65 Mon Sep 17 00:00:00 2001
From: Sergey Biryukov <sergeybiryukov.ru@gmail.com>
Date: Sun, 23 May 2021 08:51:58 +0000
Subject: [PATCH] Widgets: Make sure `WP_Widget` constructor creates a correct
 `id_base` value for a namespaced widget class.

The `id_base` value is used for the widget's `id` and `class` attributes and also for the option name which stores the widget settings (unless the widget specifies a custom `option_name` value).

With this change, any backslashes in the `id_base` for a namespaced widget class are converted to hyphens, making it easier to style the output or target the widget with JavaScript.

This also avoids a `preg_match(): Compilation failed` PHP warning from `next_widget_id_number()` on the Widgets screen, previously caused by unescaped backslashes.

Props Mte90, hermpheus, rogerlos, welcher, SergeyBiryukov.
Fixes #44098.
Built from https://develop.svn.wordpress.org/trunk@50953


git-svn-id: http://core.svn.wordpress.org/trunk@50562 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/class-wp-widget.php | 9 ++++++++-
 wp-includes/version.php         | 2 +-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/wp-includes/class-wp-widget.php b/wp-includes/class-wp-widget.php
index 8d1de7c375..b177c82053 100644
--- a/wp-includes/class-wp-widget.php
+++ b/wp-includes/class-wp-widget.php
@@ -160,7 +160,14 @@ class WP_Widget {
 	 *                                information on accepted arguments. Default empty array.
 	 */
 	public function __construct( $id_base, $name, $widget_options = array(), $control_options = array() ) {
-		$this->id_base         = empty( $id_base ) ? preg_replace( '/(wp_)?widget_/', '', strtolower( get_class( $this ) ) ) : strtolower( $id_base );
+		if ( ! empty( $id_base ) ) {
+			$id_base = strtolower( $id_base );
+		} else {
+			$id_base = preg_replace( '/(wp_)?widget_/', '', strtolower( get_class( $this ) ) );
+			$id_base = str_replace( '\\', '-', $id_base );
+		}
+
+		$this->id_base         = $id_base;
 		$this->name            = $name;
 		$this->option_name     = 'widget_' . $this->id_base;
 		$this->widget_options  = wp_parse_args(
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 935cfe79c7..66722db6da 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.8-alpha-50952';
+$wp_version = '5.8-alpha-50953';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.