Issue #2924165 by TravisCarden: Doxygen for callable arguments missing callable keyword

core/includes/bootstrap.inc

@@ -987,7 +987,7 @@ function drupal_placeholder($text) {
  * Wrapper for register_shutdown_function() that catches thrown exceptions to
  * avoid "Exception thrown without a stack frame in Unknown".
  *
- * @param $callback
+ * @param callable $callback
  *   The shutdown function to register.
  * @param ...
  *   Additional arguments to pass to the shutdown function.

core/includes/file.inc

@@ -896,7 +896,7 @@ function file_unmanaged_delete($path) {
  *
  * @param $path
  *   A string containing either an URI or a file or directory path.
- * @param $callback
+ * @param callable $callback
  *   (optional) Callback function to run on each file prior to deleting it and
  *   on each directory prior to traversing it. For example, can be used to
  *   modify permissions.

core/modules/system/system.module

@@ -450,7 +450,7 @@ function template_preprocess_entity_add_list(&$variables) {
  *  $form_state->setRedirectUrl(system_authorized_get_url());
  * @endcode
  *
- * @param $callback
+ * @param callable $callback
  *   The name of the function to invoke once the user authorizes the operation.
  * @param $file
  *   The full path to the file where the callback function is implemented.