Bootstrap/Load: Load plugin.php earlier in wp-settings.php

In order to allow non-web initializations of WordPress (such as through wp-cli) to modify things like the check for maintenance mode, plugins.php and the associated functions must be available much earlier. The use of these functions earlier than the loading of plugins is not recommended in most use cases.

Fixes #36819. See #34936.
Props jorbin, danielbachhuber for documentation.

Built from https://develop.svn.wordpress.org/trunk@37588


git-svn-id: http://core.svn.wordpress.org/trunk@37556 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/plugin.php

@@ -946,3 +946,65 @@ function _wp_filter_build_unique_id($tag, $function, $priority) {
 		return $function[0] . '::' . $function[1];
 	}
 }
+
+/**
+ * Back up global variables used for actions and filters.
+ *
+ * Prevents redefinition of these globals in advanced-cache.php from accidentally
+ * destroying existing data.
+ *
+ * @since 4.6.0
+ * @access private
+ *
+ * @global array $wp_filter         Stores all filters and actions.
+ * @global array $wp_actions        Stores the amount of times an action was triggered.
+ * @global array $merged_filters    Merges the filter hooks using this function.
+ * @global array $wp_current_filter Stores the list of current filters with the current one last.
+ * @staticvar array $backup_globals Backed up globals.
+ * @return array the staticvar from the first time it is set.
+ */
+function _backup_plugin_globals(){
+	global $wp_filter, $wp_actions, $merged_filters, $wp_current_filter;
+	static $backup_globals = array();
+	if ( empty( $backup_globals ) ) {
+		$backup_globals = array(
+			'backup_wp_filter'         => $wp_filter,
+			'backup_wp_actions'        => $wp_actions,
+			'backup_merged_filters'    => $merged_filters,
+			'backup_wp_current_filter' => $wp_current_filter,
+		);
+	};
+	return $backup_globals;
+}
+
+/**
+ * Safely restore backed up global variables used for actions and filters.
+ *
+ * @since 4.6.0
+ * @access private
+ *
+ * @global array $wp_filter         Stores all filters and actions.
+ * @global array $wp_actions        Stores the amount of times an action was triggered.
+ * @global array $merged_filters    Merges the filter hooks using this function.
+ * @global array $wp_current_filter Stores the list of current filters with the current one last.
+ * @staticvar array $backup_globals Backed up globals.
+ */
+function _restore_plugin_globals(){
+	global $wp_filter, $wp_actions, $merged_filters, $wp_current_filter;
+	$backup_globals = _backup_plugin_globals();
+	if ( $wp_filter !== $backup_globals['backup_wp_filter'] ){
+		$wp_filter = array_merge_recursive( $wp_filter, $backup_globals['backup_wp_filter'] );
+	}
+
+	if ( $wp_actions !== $backup_globals['backup_wp_actions'] ){
+		$wp_actions = array_merge_recursive( $wp_actions, $backup_globals['backup_wp_actions'] );
+	}
+
+	if ( $merged_filters !== $backup_globals['backup_merged_filters'] ){
+		$merged_filters = array_merge_recursive( $merged_filters, $backup_globals['backup_merged_filters'] );
+	}
+
+	if ( $wp_current_filter !== $backup_globals['backup_wp_current_filter'] ){
+		$wp_current_filter = array_merge_recursive( $wp_current_filter, $backup_globals['backup_wp_current_filter'] );
+	}
+}

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.6-alpha-37587';
+$wp_version = '4.6-alpha-37588';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.

wp-settings.php

@@ -20,6 +20,7 @@
 // Include files required for initialization.
 require( ABSPATH . WPINC . '/load.php' );
 require( ABSPATH . WPINC . '/default-constants.php' );
+require( ABSPATH . WPINC . '/plugin.php' );
 
 /*
  * These can't be directly globalized in version.php. When updating,
@@ -70,8 +71,11 @@
 wp_debug_mode();
 
 // For an advanced caching plugin to use. Uses a static drop-in because you would only want one.
-if ( WP_CACHE )
+if ( WP_CACHE ) {
+	_backup_plugin_globals();
 	WP_DEBUG ? include( WP_CONTENT_DIR . '/advanced-cache.php' ) : @include( WP_CONTENT_DIR . '/advanced-cache.php' );
+	_restore_plugin_globals();
+}
 
 // Define WP_LANG_DIR if not set.
 wp_set_lang_dir();
@@ -81,7 +85,6 @@
 require( ABSPATH . WPINC . '/functions.php' );
 require( ABSPATH . WPINC . '/class-wp.php' );
 require( ABSPATH . WPINC . '/class-wp-error.php' );
-require( ABSPATH . WPINC . '/plugin.php' );
 require( ABSPATH . WPINC . '/pomo/mo.php' );
 
 // Include the wpdb class and, if present, a db.php database drop-in.