Enforce checks against redeclaration for functions and classes (#52696)

Enforce checks against redeclaration for functions and classes.
See https://github.com/WordPress/gutenberg/blob/trunk/lib/README.md#wrap-functions-and-classes-with--function_exists-and--class_exists
Props: @tellthemachines @azaozz @ramonjd @anton-vlasenko

Author: anton-vlasenko

.github/CODEOWNERS

@@ -82,6 +82,7 @@
 /packages/scripts                               @gziolo @ntwb @nerrad @ajitbohra @ryanwelcher
 /packages/stylelint-config                      @ntwb
 /test/e2e                                       @kevin940726 @Mamaduka
+/test/php/gutenberg-coding-standards			@anton-vlasenko
 
 # UI Components
 /packages/components                            @ajitbohra

composer.json

@@ -32,8 +32,18 @@
 		"wp-coding-standards/wpcs": "^2.2",
 		"sirbrillig/phpcs-variable-analysis": "^2.8",
 		"spatie/phpunit-watcher": "^1.23",
-		"yoast/phpunit-polyfills": "^1.0"
+		"yoast/phpunit-polyfills": "^1.0",
+		"gutenberg/gutenberg-coding-standards": "@dev"
 	},
+	"repositories": [
+		{
+			"type": "path",
+			"url": "./test/php/gutenberg-coding-standards",
+			"options": {
+				"symlink": false
+			}
+		}
+	],
 	"require": {
 		"composer/installers": "~1.0"
 	},

lib/class-wp-duotone-gutenberg.php

@@ -32,6 +32,10 @@
  * @since 6.3.0
  */
 
+if ( class_exists( 'WP_Duotone_Gutenberg' ) ) {
+	return;
+}
+
 /**
  * Manages duotone block supports and global styles.
  *

lib/class-wp-theme-json-data-gutenberg.php

@@ -6,6 +6,10 @@
  * @since 6.1.0
  */
 
+if ( class_exists( 'WP_Theme_JSON_Data_Gutenberg' ) ) {
+	return;
+}
+
 /**
  * Class to provide access to update a theme.json structure.
  */

lib/class-wp-theme-json-gutenberg.php

@@ -6,6 +6,10 @@
  * @since 5.8.0
  */
 
+if ( class_exists( 'WP_Theme_JSON_Gutenberg' ) ) {
+	return;
+}
+
 /**
  * Class that encapsulates the processing of structures that adhere to the theme.json spec.
  *

lib/class-wp-theme-json-resolver-gutenberg.php

@@ -6,6 +6,10 @@
  * @since 5.8.0
  */
 
+if ( class_exists( 'WP_Theme_JSON_Resolver_Gutenberg' ) ) {
+	return;
+}
+
 /**
  * Class that abstracts the processing of the different data sources
  * for site-level config and offers an API to work with them.

lib/compat/wordpress-6.2/html-api/class-wp-html-attribute-token.php

@@ -7,6 +7,10 @@
  * @since 6.2.0
  */
 
+if ( class_exists( 'WP_HTML_Attribute_Token' ) ) {
+	return;
+}
+
 /**
  * Data structure for the attribute token that allows to drastically improve performance.
  *

lib/compat/wordpress-6.2/html-api/class-wp-html-span.php

@@ -7,6 +7,10 @@
  * @since 6.2.0
  */
 
+if ( class_exists( 'WP_HTML_Span' ) ) {
+	return;
+}
+
 /**
  * Represents a textual span inside an HTML document.
  *

lib/compat/wordpress-6.2/html-api/class-wp-html-tag-processor.php

@@ -26,6 +26,10 @@
  * @since 6.2.0
  */
 
+if ( class_exists( 'WP_HTML_Tag_Processor' ) ) {
+	return;
+}
+
 /**
  * Modifies attributes in an HTML document for tags matching a query.
  *

lib/compat/wordpress-6.2/html-api/class-wp-html-text-replacement.php

@@ -7,6 +7,10 @@
  * @since 6.2.0
  */
 
+if ( class_exists( 'WP_HTML_Text_Replacement' ) ) {
+	return;
+}
+
 /**
  * Data structure used to replace existing content from start to end that allows to drastically improve performance.
  *