completionSearch: try an exact match even if the backend returns no result

Unfortunately some backends (like Cirrus) are not able to do proper crossnamespace
lookup. If the backend returns no result we should still try an exact title match.

Bug:T129575
Change-Id: Ic08ec0aac0fd8a289f21753d74ae62ba509de841

diff --git a/includes/search/SearchEngine.php b/includes/search/SearchEngine.php
index 1344f4c..b263fb3 100644 (file)
--- a/includes/search/SearchEngine.php
+++ b/includes/search/SearchEngine.php
@@ -708,10 +708,6 @@ class SearchEngine {
         * @return SearchSuggestionSet
         */
        protected function processCompletionResults( $search, SearchSuggestionSet $suggestions ) {
-               if ( $suggestions->getSize() == 0 ) {
-                       // If we don't have anything, don't bother
-                       return $suggestions;
-               }
                $search = trim( $search );
                // preload the titles with LinkBatch
                $titles = $suggestions->map( function( SearchSuggestion $sugg ) {
@@ -726,6 +722,10 @@ class SearchEngine {
                } );
 
                // Rescore results with an exact title match
+               // NOTE: in some cases like cross-namespace redirects
+               // (frequently used as shortcuts e.g. WP:WP on huwiki) some
+               // backends like Cirrus will return no results. We should still
+               // try an exact title match to workaround this limitation
                $rescorer = new SearchExactMatchRescorer();
                $rescoredResults = $rescorer->rescore( $search, $this->namespaces, $results, $this->limit );