From 2c7c677f2594e99cebb86832e2f5da8f42c2444d Mon Sep 17 00:00:00 2001
From: Sergey Biryukov <sergeybiryukov@git.wordpress.org>
Date: Mon, 24 May 2021 09:50:30 +0000
Subject: [PATCH] Widgets: Make sure `WP_Widget` constructor creates a correct
 `classname` value for a namespaced widget class.

This reverts the changes to `id_base` from [50953] due to backward compatibility concerns, and instead focuses on the `id` and `class` attributes specifically.

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

Follow-up to [50953].

Fixes #44098.

git-svn-id: https://develop.svn.wordpress.org/trunk@50961 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-admin/includes/widgets.php   |  2 +-
 src/wp-includes/class-wp-widget.php |  3 +--
 src/wp-includes/widgets.php         |  9 +++++++--
 tests/phpunit/tests/widgets.php     | 18 +++++++++---------
 4 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/src/wp-admin/includes/widgets.php b/src/wp-admin/includes/widgets.php
index ac98cdb527..af33787fa6 100644
--- a/src/wp-admin/includes/widgets.php
+++ b/src/wp-admin/includes/widgets.php
@@ -162,7 +162,7 @@ function next_widget_id_number( $id_base ) {
 	$number = 1;
 
 	foreach ( $wp_registered_widgets as $widget_id => $widget ) {
-		if ( preg_match( '/' . $id_base . '-([0-9]+)$/', $widget_id, $matches ) ) {
+		if ( preg_match( '/' . preg_quote( $id_base, '/' ) . '-([0-9]+)$/', $widget_id, $matches ) ) {
 			$number = max( $number, $matches[1] );
 		}
 	}
diff --git a/src/wp-includes/class-wp-widget.php b/src/wp-includes/class-wp-widget.php
index b177c82053..71381d35e6 100644
--- a/src/wp-includes/class-wp-widget.php
+++ b/src/wp-includes/class-wp-widget.php
@@ -164,7 +164,6 @@ class WP_Widget {
 			$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;
@@ -173,7 +172,7 @@ class WP_Widget {
 		$this->widget_options  = wp_parse_args(
 			$widget_options,
 			array(
-				'classname'                   => $this->option_name,
+				'classname'                   => str_replace( '\\', '_', $this->option_name ),
 				'customize_selective_refresh' => false,
 			)
 		);
diff --git a/src/wp-includes/widgets.php b/src/wp-includes/widgets.php
index 1987023463..6030ecc9fc 100644
--- a/src/wp-includes/widgets.php
+++ b/src/wp-includes/widgets.php
@@ -753,8 +753,13 @@ function dynamic_sidebar( $index = 1 ) {
 				$classname_ .= '_' . get_class( $cn );
 			}
 		}
-		$classname_                 = ltrim( $classname_, '_' );
-		$params[0]['before_widget'] = sprintf( $params[0]['before_widget'], $id, $classname_ );
+		$classname_ = ltrim( $classname_, '_' );
+
+		$params[0]['before_widget'] = sprintf(
+			$params[0]['before_widget'],
+			str_replace( '\\', '_', $id ),
+			$classname_
+		);
 
 		/**
 		 * Filters the parameters passed to a widget's display callback.
diff --git a/tests/phpunit/tests/widgets.php b/tests/phpunit/tests/widgets.php
index 7a82b58fc5..4c34dfcd73 100644
--- a/tests/phpunit/tests/widgets.php
+++ b/tests/phpunit/tests/widgets.php
@@ -428,42 +428,42 @@ class Tests_Widgets extends WP_UnitTestCase {
 	/**
 	 * @ticket 44098
 	 * @see WP_Widget::__construct()
-	 * @dataProvider data_wp_widget_id_base
+	 * @dataProvider data_wp_widget_classname
 	 */
-	function test_wp_widget_id_base( $expected, $widget_class ) {
+	function test_wp_widget_classname( $expected, $widget_class ) {
 		require_once DIR_TESTDATA . '/widgets/custom-widget-classes.php';
 
 		$widget = new $widget_class( '', 'Foo' );
 
-		$this->assertSame( $expected, $widget->id_base );
+		$this->assertSame( $expected, $widget->widget_options['classname'] );
 	}
 
 	/**
 	 * Data provider.
 	 *
-	 * Passes the expected `id_base` value and the class name.
+	 * Passes the expected `classname` value and the PHP class name.
 	 *
 	 * @since 5.8.0
 	 *
 	 * @return array {
 	 *     @type array {
-	 *         @type string $expected     The expected `id_base` value to be returned.
+	 *         @type string $expected     The expected `classname` value to be returned.
 	 *         @type string $widget_class The widget class name for creating an instance.
 	 *     }
 	 * }
 	 */
-	function data_wp_widget_id_base() {
+	function data_wp_widget_classname() {
 		return array(
 			array(
-				'search',
+				'widget_search',
 				'WP_Widget_Search',
 			),
 			array(
-				'test-sub-sub-namespaced_widget',
+				'widget_test_sub_sub_namespaced_widget',
 				'Test\Sub\Sub\Namespaced_Widget',
 			),
 			array(
-				'non_namespaced_widget',
+				'widget_non_namespaced_widget',
 				'Non_Namespaced_Widget',
 			),
 		);