Issue #2002280 by elvis2, connork: Rename Views method add_signature() to addSignature().

core/modules/views/lib/Drupal/views/Plugin/views/query/QueryPluginBase.php

@@ -79,7 +79,7 @@ function execute(ViewExecutable $view) {  }
    * @param view $view
    *   The view which is executed.
    */
-  function add_signature(ViewExecutable $view) { }
+  public function addSignature(ViewExecutable $view) { }
 
   /**
    * Get aggregation info for group by queries.

core/modules/views/lib/Drupal/views/Plugin/views/query/Sql.php

@@ -1643,7 +1643,7 @@ function loadEntities(&$results) {
     }
   }
 
-  function add_signature(ViewExecutable $view) {
+  public function addSignature(ViewExecutable $view) {
     $view->query->add_field(NULL, "'" . $view->storage->id() . ':' . $view->current_display . "'", 'view_name');
   }
 

core/modules/views/lib/Drupal/views/ViewExecutable.php

@@ -1071,7 +1071,7 @@ public function build($display_id = NULL) {
     }
 
     if (config('views.settings')->get('sql_signature')) {
-      $this->query->add_signature($this);
+      $this->query->addSignature($this);
     }
 
     // Let modules modify the query just prior to finalizing it.