Ticket #51525: typed-apply-filters.patch

src/wp-includes/class-wp-hook.php

@@ -267 +267 @@
          * @return mixed The filtered value after all hooked functions are applied to it.
          */
         public function apply_filters( $value, $args ) {
+                return $this->apply_filters_typed( 'mixed', $value, $args );
+        }
+
+        /**
+         * Calls the callback functions that have been added to a filter hook in a typesafe manner.
+         *
+         * @since 5.8.0
+         *
+         * @param mixed $value The value to filter.
+         * @param array $args  Additional parameters to pass to the callback functions.
+         *                     This array is expected to include $value at index 0.
+         * @return mixed The filtered value after all hooked functions are applied to it.
+         */
+        public function apply_filters_typesafe( $value, $args ) {
+                return $this->apply_filters_typed( gettype( $value ), $value, $args );
+        }
+
+        /**
+         * Calls the callback functions that have been added to a filter hook in a typed manner.
+         *
+         * @since 5.8.0
+         *
+         * @param mixed $value The value to filter.
+         * @param array $args  Additional parameters to pass to the callback functions.
+         *                     This array is expected to include $value at index 0.
+         * @return mixed The filtered value after all hooked functions are applied to it.
+         */
+        public function apply_filters_typed( $type, $value, $args ) {
                 if ( ! $this->callbacks ) {
                         return $value;
                 }
@@ -287 +315 @@
 
                                 // Avoid the array_slice() if possible.
                                 if ( 0 == $the_['accepted_args'] ) {
-                                        $value = call_user_func( $the_['function'] );
+                                        $next_value = call_user_func( $the_['function'] );
                                 } elseif ( $the_['accepted_args'] >= $num_args ) {
-                                        $value = call_user_func_array( $the_['function'], $args );
+                                        $next_value = call_user_func_array( $the_['function'], $args );
                                 } else {
-                                        $value = call_user_func_array( $the_['function'], array_slice( $args, 0, (int) $the_['accepted_args'] ) );
+                                        $next_value = call_user_func_array( $the_['function'], array_slice( $args, 0, (int) $the_['accepted_args'] ) );
+                                }
+                                if ( ! is_type( $type, $next_value ) ) {
+                                        _doing_it_wrong(
+                                                $the_['function'],
+                                                sprintf(
+                                                        __( 'Invalid type returned in filter. Expected %1$s but received %2$s' ),
+                                                        $type,
+                                                        gettype( $next_value )
+                                                ),
+                                                '5.8'
+                                        );
                                 }
+                                $value = $next_value;
                         }
                 } while ( false !== next( $this->iterations[ $nesting_level ] ) );
 

src/wp-includes/load.php

@@ -1517 +1517 @@
         return $is_wp_error;
 }
 
+/**
+ * Checks whether the given variable is a certain type.
+ *
+ * Returns whether `$value` is certain type.
+ *
+ * @since 5.8.0
+ *
+ * @param string $type  The type to check.
+ * @param mixed  $value The variable to check.
+ * @return bool Whether the variable is of the type.
+ */
+function is_type( $type, $value ) {
+        switch( $type ) {
+                case 'boolean':
+                        return is_bool( $value );
+                case 'integer':
+                        return is_int( $value );
+                case 'double':
+                        return is_float( $value );
+                case 'string':
+                        return is_string( $value );
+                case 'array':
+                        return is_array( $value );
+                case 'object':
+                        return is_object( $value );
+                case 'resource':
+                case 'resource (closed)':
+                        return is_resource( $value );
+                case 'NULL':
+                        return is_null( $value );
+                case 'unknown_type':
+                        return false;
+                case 'mixed':
+                        return true;
+                default:
+                        return is_a( $value, $type ) || is_subclass_of( $value, $type );
+        }
+}
+
 /**
  * Determines whether file modifications are allowed.
  *

src/wp-includes/plugin.php

@@ -184 +184 @@
  * @param mixed  ...$args Additional parameters to pass to the callback functions.
  * @return mixed The filtered value after all hooked functions are applied to it.
  */
-function apply_filters( $tag, $value ) {
+function apply_filters( $tag, $value, ...$args ) {
+        return apply_filters_typed( 'mixed', $tag, $value, ...$args );
+}
+
+/**
+ * Calls the callback functions that have been added to a filter hook in a typesafe manner.
+ *
+ * @param string $tag     The name of the filter hook.
+ * @param mixed  $value   The value to filter.
+ * @param mixed  ...$args Additional parameters to pass to the callback functions.
+ * @return mixed The filtered value after all hooked functions are applied to it.
+ */
+function apply_filters_typesafe( $tag, $value, ...$args ) {
+        return apply_filters_typed( gettype( $value ), $tag, $value, ...$args );
+}
+
+/**
+ * Calls the callback functions that have been added to a filter hook in a typed manner.
+ *
+ * @param string $type    The type the return value should have.
+ * @param string $tag     The name of the filter hook.
+ * @param mixed  $value   The value to filter.
+ * @param mixed  ...$args Additional parameters to pass to the callback functions.
+ * @return mixed The filtered value after all hooked functions are applied to it.
+ */
+function apply_filters_typed( $type, $tag, $value ) {
         global $wp_filter, $wp_current_filter;
 
         $args = func_get_args();
+        // Don't pass the type to the 'all' actions.
+        array_shift( $args );
 
         // Do 'all' actions first.
         if ( isset( $wp_filter['all'] ) ) {
@@ -209 +236 @@
         // Don't pass the tag name to WP_Hook.
         array_shift( $args );
 
-        $filtered = $wp_filter[ $tag ]->apply_filters( $value, $args );
+        $filtered = $wp_filter[ $tag ]->apply_filters_typed( $type, $value, $args );
 
         array_pop( $wp_current_filter );