Stdlib: ParentIterator under RecursiveIteratorIterator yields nothing — Zend visits parent nodes (ext/spl/spl_iterators.c) #22007

Category

bug · php-src-strict · SPL ParentIterator + RII

Problem

ParentIterator alone correctly skips non-parent elements (manual rewind/valid/next matches Zend). Wrapping it in RecursiveIteratorIterator (SELF_FIRST or CHILD_FIRST) yields zero iterations on the VM, while Zend visits each parent node once.

Related closed work (#19784 instanceof, #13211 rewind) does not cover this RII nesting gap.

php-src reference

• php/php-src ext/spl/spl_iterators.c — ParentIterator / spl_dual_it_* + RecursiveIteratorIterator descent via hasChildren/getChildren

PHP implementation target

• ext/spl/ParentIteratorBuiltin.php — hasChildren / getChildren / accept filter interaction with RII
• ext/spl/ RecursiveIteratorIterator implementation (peer of Regression: ParentIterator/RecursiveRegexIterator not instanceof RecursiveIterator — RII rejects (ext/spl/spl_iterators.c) #19784) — ensure ParentIterator children are walked when hasChildren()===true
• Prefer PHP-in-PHP; no new runtime/*.c logic

Repro

./script/docker-exec.sh -- bash -lc 'php bin/vm.php -r '\''
$n=0;
foreach (new RecursiveIteratorIterator(
  new ParentIterator(new RecursiveArrayIterator([1,[2,3],4])),
  RecursiveIteratorIterator::SELF_FIRST
) as $k=>$v) { $n++; echo "k=$k arr=".(is_array($v)?"1":"0")."\n"; }
echo "count=$n\n";
'\'''

Expect Zend: count=1. VM today: count=0.

Done when

• RII + ParentIterator SELF_FIRST / CHILD_FIRST match Zend visit order and count on nested RecursiveArrayIterator
• Manual ParentIterator iteration remains green
• Compliance .phpt under test/compliance/cases/spl/
• php-src-strict; no php-compiler-strict shortcut