Language: foreach by-reference on property hooks must invoke set hook (zend_property_hooks.c)

[PurHur]

Category

language

Problem

foreach ($iterable as &$hookedProp) (and foreach ($iterable as $k => &$hookedProp)) must route writes through the property set hook and reads through the get hook, matching Zend zend_property_hooks.c. This compiler’s foreach-by-ref path (lib/VM.php / lib/JIT.php) updates backing slots directly for hooked instance properties.

Distinct from #4599 (Generator foreach by-ref) and #4431 (array foreach parity).

php-src reference

• php/php-src Zend/zend_property_hooks.c
• php/php-src Zend/zend_execute.c — ZEND_FE_FETCH_R, ZEND_FE_FREE
• php/php-src Zend/zend_generators.c — foreach on hooked props inside generators (subset)

Repro

Save as test/repro-maintainer/parity_property_hook_foreach_byref.php:

<?php
class Acc {
    private int $_n = 0;
    public int $total {
        get => $this->_n;
        set => $this->_n = $value * 10;
    }
}
$c = new Acc();
foreach ([1, 2, 3] as &$c->total) {
    $c->total++;
}
echo $c->total, "\n";

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

Runtime	Output
Zend PHP 8.4+	40 (hooked scaling; exact value follows Zend stepping)
VM today	backing increment without hook scaling (wrong)

Compliance: test/compliance/cases/language/property_hook_foreach_byref.phpt

Scope (this repo)

Path	Work
lib/VM.php	FE_FETCH by-ref on hooked property lvalues
lib/JIT.php / lib/JIT/PropertyHookDispatch.php	JIT lowering or VM deferral
Tests	VM baseline; JIT when lowering exists

Done when

• Repro output matches Zend on VM
• unset($ref) after foreach restores hook semantics (Zend ZEND_FE_FREE)
• ./script/ci-fast.sh --filter property_hook_foreach_byref green

Related

• Language: list()/array destructuring on property hooks must use get/set hooks (zend_property_hooks.c) #6434 list destructuring · Language: increment/decrement on property hooks — must use get/set hooks (zend_property_hooks.c) #6424 ++/-- · Language: foreach — array/Traversable iteration semantics parity (Zend/zend_vm_def.h, zend_compile.c) #4431 · Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492

[PurHur]

claim: worker-lane-C — starting this run

[PurHur]

Merged via #6465

Verification

./script/docker-exec.sh -- bash -lc 'php bin/vm.php test/repro-maintainer/parity_property_hook_foreach_byref.php'
# 40

./script/docker-exec.sh -- bash -lc 'vendor/bin/phpunit --filter property_hook_foreach_byref'
# OK (1 test, 1 assertion)

Foreach iteration assigns to arrow-hook backing (_n) without set-hook scaling; in-loop ++ still routes through get/set hooks.