diff -u b/core/modules/system/system.api.php b/core/modules/system/system.api.php
--- b/core/modules/system/system.api.php
+++ b/core/modules/system/system.api.php
@@ -990,11 +990,8 @@
  *     module registers the 'search_result' theme hook, 'search-result' will be
  *     assigned as its template name.
  *   - function: If specified, this will be the function name to invoke for
- *     this implementation. If neither 'template' nor 'function' is specified,
- *     a default template name will be assumed. If neither 'template' nor
- *     'function' are specified, a default template name will be assumed. For
- *     example, if a module registers the 'search_result' theme hook,
- *     'search-result' will be assigned as its template name.
+ *     this implementation. If neither 'template' nor 'function' are specified,
+ *     a default template name will be assumed. See above for more details.
  *   - base hook: Used for _theme() suggestions only: the base theme hook name.
  *     Instead of this suggestion's implementation being used directly, the base
  *     hook will be invoked with this implementation as its first suggestion.