Merge "Simplify canUpdateTags function in ChangeTags"

diff --git a/includes/changetags/ChangeTags.php b/includes/changetags/ChangeTags.php
index 79763bd..f712b26 100644 (file)
--- a/includes/changetags/ChangeTags.php
+++ b/includes/changetags/ChangeTags.php
@@ -417,21 +417,23 @@ class ChangeTags {
                        return Status::newFatal( 'tags-update-no-permission' );
                }
 
-               // to be added, a tag has to be explicitly defined
-               // @todo Allow extensions to define tags that can be applied by users...
-               $explicitlyDefinedTags = self::listExplicitlyDefinedTags();
-               $diff = array_diff( $tagsToAdd, $explicitlyDefinedTags );
-               if ( $diff ) {
-                       return self::restrictedTagError( 'tags-update-add-not-allowed-one',
-                               'tags-update-add-not-allowed-multi', $diff );
+               if ( $tagsToAdd ) {
+                       // to be added, a tag has to be explicitly defined
+                       // @todo Allow extensions to define tags that can be applied by users...
+                       $explicitlyDefinedTags = self::listExplicitlyDefinedTags();
+                       $diff = array_diff( $tagsToAdd, $explicitlyDefinedTags );
+                       if ( $diff ) {
+                               return self::restrictedTagError( 'tags-update-add-not-allowed-one',
+                                       'tags-update-add-not-allowed-multi', $diff );
+                       }
                }
 
-               // to be removed, a tag has to be either explicitly defined or not defined
-               // at all
-               $definedTags = self::listDefinedTags();
-               $diff = array_diff( $tagsToRemove, $explicitlyDefinedTags );
-               if ( $diff ) {
-                       $intersect = array_intersect( $diff, $definedTags );
+               if ( $tagsToRemove ) {
+                       // to be removed, a tag must not be defined by an extension, or equivalently it
+                       // has to be either explicitly defined or not defined at all
+                       // (assuming no edge case of a tag both explicitly-defined and extension-defined)
+                       $extensionDefinedTags = self::listExtensionDefinedTags();
+                       $intersect = array_intersect( $tagsToRemove, $extensionDefinedTags );
                        if ( $intersect ) {
                                return self::restrictedTagError( 'tags-update-remove-not-allowed-one',
                                        'tags-update-remove-not-allowed-multi', $intersect );