Runtime: gc_collect_cycles() — run cyclic GC (Zend GC parity)

[PurHur]

Category

runtime

Problem

gc_collect_cycles() is not available. Zend’s refcount + cycle collector frees unreachable object graphs; long-lived apps and tests call it explicitly. This compiler exposes a WeakReference subset (#1366) without a public sweep entry point.

php-src reference

• Zend/zend_gc.c — gc_collect_cycles(), zend_gc_collect_cycles()
• ext/standard/info.c — PHP_FUNCTION(gc_collect_cycles)

Repro (today)

<?php
class Node { public ?Node $next = null; }
$a = new Node();
$b = new Node();
$a->next = $b;
$b->next = $a;
unset($a, $b);
echo gc_collect_cycles();

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php repro.php'

Zend PHP: integer ≥ 1 (cycles collected)
This compiler: Call to undefined function gc_collect_cycles()

Scope

• ext/standard/gc_collect_cycles.php + Module.php
• VM: hook into object refcount / cycle buffer (implement real collector or document v1 stub with follow-up)
• test/compliance/cases/runtime/gc_collect_cycles.phpt

Done when

• Repro runs without undefined function
• Return value matches Zend on a simple 2-node cycle after unset
• ./script/ci-fast.sh --filter gc_collect_cycles green

Links

• Language: WeakReference and WeakMap #1366 · Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492 · 🗺️ ROADMAP: Self-host + web-capable PHP subset (living) #78

[PurHur]

claim: cursor-agent-lane-c — starting this run

[PurHur]

Closed by #3139 (gc_collect_cycles VM + compliance test).