fixed the filter filter

CHANGELOG

@@ -1,5 +1,6 @@
 * 2.11.3 (2019-XX-XX)
 
+ * fixed the filter filter (allow the result to be used several times)
  * fixed macro auto-import when a template contains only macros
 
 * 2.11.2 (2019-06-05)

src/Extension/CoreExtension.php

@@ -1522,11 +1522,12 @@ function twig_array_column($array, $name): array
 
 function twig_array_filter($array, $arrow)
 {
-    foreach ($array as $k => $v) {
-        if ($arrow($v, $k)) {
-            yield $k => $v;
-        }
+    if (\is_array($array)) {
+        return array_filter($array, $arrow, \ARRAY_FILTER_USE_BOTH);
     }
+
+    // the IteratorIterator wrapping is needed as some internal PHP classes are \Traversable but do not implement \Iterator
+    return new \CallbackFilterIterator(new \IteratorIterator($array), $arrow);
 }
 
 function twig_array_map($array, $arrow)

test/Twig/Tests/Fixtures/filters/filter.test

@@ -35,6 +35,11 @@
 {% for k, v in xml|filter(x => true) %}
 {{ k }}/{{ v }}
 {% endfor %}
+
+{% set coll = ['a', 'b']|filter(v => v is same as('a')) %}
+{% if coll|length > 0 %}
+    {{- coll|join(', ') }}
+{% endif %}
 --DATA--
 return [
     'it' => new \ArrayIterator(['a' => 1, 'b' => 2, 'c' => 5, 'd' => 8]),
@@ -68,3 +73,5 @@ elem/baz
 elem/foo
 elem/bar
 elem/baz
+
+a