diff --git a/src/wp-includes/plugin.php b/src/wp-includes/plugin.php
index edc0fda4cd..53058f39a8 100644
--- a/src/wp-includes/plugin.php
+++ b/src/wp-includes/plugin.php
@@ -76,7 +76,7 @@ if ( ! isset( $wp_current_filter ) )
  *                                  and functions with the same priority are executed
  *                                  in the order in which they were added to the action.
  * @param int      $accepted_args   Optional. The number of arguments the function accepts. Default 1.
- * @return boolean true
+ * @return true
  */
 function add_filter( $tag, $function_to_add, $priority = 10, $accepted_args = 1 ) {
 	global $wp_filter, $merged_filters;
@@ -96,12 +96,12 @@ function add_filter( $tag, $function_to_add, $priority = 10, $accepted_args = 1
  *
  * @param string        $tag               The name of the filter hook.
  * @param callback|bool $function_to_check Optional. The callback to check for. Default false.
- * @return bool|int If $function_to_check is omitted, returns boolean for whether the hook has
- *                  anything registered. When checking a specific function, the priority of that
- *                  hook is returned, or false if the function is not attached. When using the
- *                  $function_to_check argument, this function may return a non-boolean value
- *                  that evaluates to false (e.g.) 0, so use the === operator for testing the
- *                  return value.
+ * @return false|int If $function_to_check is omitted, returns boolean for whether the hook has
+ *                   anything registered. When checking a specific function, the priority of that
+ *                   hook is returned, or false if the function is not attached. When using the
+ *                   $function_to_check argument, this function may return a non-boolean value
+ *                   that evaluates to false (e.g.) 0, so use the === operator for testing the
+ *                   return value.
  */
 function has_filter($tag, $function_to_check = false) {
 	// Don't reset the internal array pointer
@@ -124,7 +124,7 @@ function has_filter($tag, $function_to_check = false) {
 		}
 	}
 
-	if ( false === $function_to_check || false == $has )
+	if ( false === $function_to_check || false === $has )
 		return $has;
 
 	if ( !$idx = _wp_filter_build_unique_id($tag, $function_to_check, false) )
@@ -288,10 +288,13 @@ function apply_filters_ref_array($tag, $args) {
  *
  * @since 1.2.0
  *
+ * @global array $wp_filter         Stores all of the filters
+ * @global array $merged_filters    Merges the filter hooks using this function.
+ *
  * @param string   $tag                The filter hook to which the function to be removed is hooked.
  * @param callback $function_to_remove The name of the function which should be removed.
  * @param int      $priority           Optional. The priority of the function. Default 10.
- * @return boolean Whether the function existed before it was removed.
+ * @return bool    Whether the function existed before it was removed.
  */
 function remove_filter( $tag, $function_to_remove, $priority = 10 ) {
 	$function_to_remove = _wp_filter_build_unique_id( $tag, $function_to_remove, $priority );
@@ -317,9 +320,12 @@ function remove_filter( $tag, $function_to_remove, $priority = 10 ) {
  *
  * @since 2.7.0
  *
+ * @global array $wp_filter         Stores all of the filters
+ * @global array $merged_filters    Merges the filter hooks using this function.
+ *
  * @param string   $tag      The filter to remove hooks from.
  * @param int|bool $priority Optional. The priority number to remove. Default false.
- * @return bool True when finished.
+ * @return true True when finished.
  */
 function remove_all_filters( $tag, $priority = false ) {
 	global $wp_filter, $merged_filters;
@@ -342,6 +348,8 @@ function remove_all_filters( $tag, $priority = false ) {
  *
  * @since 2.5.0
  *
+ * @global array $wp_current_filter Stores the list of current filters with the current one last
+ *
  * @return string Hook name of the current filter or action.
  */
 function current_filter() {
@@ -422,7 +430,7 @@ function doing_action( $action = null ) {
  *                                  and functions with the same priority are executed
  *                                  in the order in which they were added to the action.
  * @param int      $accepted_args   Optional. The number of arguments the function accept. Default 1.
- * @return bool Will always return true.
+ * @return true Will always return true.
  */
 function add_action($tag, $function_to_add, $priority = 10, $accepted_args = 1) {
 	return add_filter($tag, $function_to_add, $priority, $accepted_args);
@@ -440,13 +448,14 @@ function add_action($tag, $function_to_add, $priority = 10, $accepted_args = 1)
  *
  * @since 1.2.0
  *
- * @global array $wp_filter  Stores all of the filters
- * @global array $wp_actions Increments the amount of times action was triggered.
+ * @global array $wp_filter         Stores all of the filters
+ * @global array $wp_actions        Increments the amount of times 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
  *
  * @param string $tag The name of the action to be executed.
  * @param mixed  $arg Optional. Additional arguments which are passed on to the
  *                    functions hooked to the action. Default empty.
- * @return null Will return null if $tag does not exist in $wp_filter array.
  */
 function do_action($tag, $arg = '') {
 	global $wp_filter, $wp_actions, $merged_filters, $wp_current_filter;
@@ -524,12 +533,13 @@ function did_action($tag) {
  *
  * @see do_action() This function is identical, but the arguments passed to the
  *                  functions hooked to $tag< are supplied using an array.
- * @global array $wp_filter  Stores all of the filters
- * @global array $wp_actions Increments the amount of times action was triggered.
+ * @global array $wp_filter         Stores all of the filters
+ * @global array $wp_actions        Increments the amount of times 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
  *
  * @param string $tag  The name of the action to be executed.
  * @param array  $args The arguments supplied to the functions hooked to `$tag`.
- * @return null Will return null if `$tag` does not exist in `$wp_filter` array.
  */
 function do_action_ref_array($tag, $args) {
 	global $wp_filter, $wp_actions, $merged_filters, $wp_current_filter;
@@ -618,7 +628,7 @@ function remove_action( $tag, $function_to_remove, $priority = 10 ) {
  *
  * @param string   $tag      The action to remove hooks from.
  * @param int|bool $priority The priority number to remove them from. Default false.
- * @return bool True when finished.
+ * @return true True when finished.
  */
 function remove_all_actions($tag, $priority = false) {
 	return remove_all_filters($tag, $priority);
@@ -635,6 +645,8 @@ function remove_all_actions($tag, $priority = false) {
  *
  * @since 1.5.0
  *
+ * @global array $wp_plugin_paths
+ *
  * @param string $file The filename of plugin.
  * @return string The name of a plugin.
  */
@@ -665,6 +677,11 @@ function plugin_basename( $file ) {
  *
  * @see plugin_basename()
  *
+ * @global array $wp_plugin_paths
+ *
+ * @staticvar string $wp_plugin_path
+ * @staticvar string $wpmu_plugin_path
+ *
  * @param string $file Known path to the file.
  * @return bool Whether the path was able to be registered.
  */
@@ -819,6 +836,8 @@ function register_uninstall_hook( $file, $callback ) {
  * @since 2.5.0
  * @access private
  *
+ * @global array $wp_filter  Stores all of the filters
+ *
  * @param array $args The collected parameters from the hook that was called.
  */
 function _wp_call_all_hook($args) {
@@ -856,15 +875,16 @@ function _wp_call_all_hook($args) {
  * @access private
  *
  * @global array $wp_filter Storage for all of the filters and actions.
+ * @staticvar int $filter_id_count
  *
  * @param string   $tag      Used in counting how many hooks were applied
  * @param callback $function Used for creating unique id
  * @param int|bool $priority Used in counting how many hooks were applied. If === false
  *                           and $function is an object reference, we return the unique
  *                           id only if it already has one, false otherwise.
- * @return string|bool Unique ID for usage as array key or false if $priority === false
- *                     and $function is an object reference, and it does not already have
- *                     a unique id.
+ * @return string|false Unique ID for usage as array key or false if $priority === false
+ *                      and $function is an object reference, and it does not already have
+ *                      a unique id.
  */
 function _wp_filter_build_unique_id($tag, $function, $priority) {
 	global $wp_filter;