Element::isEmpty() should check for #weight property

public static function isEmpty(array $elements) {
- return empty($elements) || (count($elements) === 1 && array_keys($elements) === ['#cache']);
+ // Early check.
+ if (empty($elements)) {
+ return TRUE;
+ }
+ $is_empty = FALSE;
+ $element_keys = array_keys($elements);
+ // Sort so we know the which elements are where.
+ sort($element_keys);
+ $count = count($element_keys);
+ // Use strict comparison.
+ switch (TRUE) {
+ case ($count === 1):
+ // Sort by most common for performance.
+ if (($element_keys === ['#cache'])
+ || ($element_keys === ['#weight'])
+ || ($element_keys === ['#attached'])) {
+ $is_empty = TRUE;
+ }
+
+ case ($count === 2):
+ if (($element_keys === ['#cache', '#weight'])
+ || ($element_keys === ['#attached', '#weight'])
+ || ($element_keys === ['#attached', '#cache'])) {
+ $is_empty = TRUE;
+ }
+
+ case ($count === 3):
+ if ($element_keys === ['#attached', '#cache', '#weight']) {
+ $is_empty = TRUE;
+ }
+
+ }
+ return $is_empty;
}

There are simpler ways to check this.

return \array_diff(\array_keys($elements), ['#cache', '#weight', '#attached']) === [];

unset($elements['#cache'], $elements['#weight'], $elements['#attached']);
return $elements === [];

Also method documentation needs to be updated.

Thank you.

Sounds like elements with #attached property shouldn't be considered as empty.

@miiimooo Ok, I think it's better to continue work in #3333858: Blocks that have #attached set removed after upgrade.