Language: property hook set — exception from hook must abort assignment, try block must not resume (Zend/zend_property_hooks.c) #9670

Category

language · php-src-strict · PHP 8.4 property hooks · sibling to #9666 (unset hook)

Problem

When a property set hook throws (or a readonly hooked write raises Error), the exception reaches the caller's catch, but the VM resumes the try block after the handler as if the write succeeded. Zend aborts the assignment and does not execute subsequent statements in the try.

<?php
class C {
    public int $x {
        get => $this->x;
        set { throw new Exception('set hook'); }
    }
    private int $x = 0;
}
$c = new C();
try {
    $c->x = 1;
    echo "no-resume\n"; // VM prints after catch — wrong
} catch (Throwable $e) {
    echo 'caught: ', $e->getMessage(), "\n";
}
// Zend (8.4): only "caught: set hook"

Same symptom for readonly class + hooked property write (Error: Cannot modify readonly property then no-resume).

php-src reference

• php/php-src Zend/zend_property_hooks.c — set hook dispatch + exception propagation
• php/php-src Zend/zend_execute.c — exception unwinding must not resume completed try range after catch

Repro

• test/repro/maintainer_gap_property_hook_set_exception.php
• test/repro/maintainer_gap_readonly_hook_write_exception.php

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

Implementation hints (PHP-in-PHP)

• Fix property-hook write exception path in lib/VM.php — same class of bug as Language: property hook unset — exception from hook must abort unset and propagate (Zend/zend_property_hooks.c) #9666 (unset hook); share unwinding helper
• Do not swallow hook throws in trampolines; do not re-enter try block after catch
• No new C runtime logic

Scope

• lib/VM.php property hook set / readonly write opcodes
• Compliance guard under test/compliance/cases/language/

Done when

• Set-hook repro prints only caught: set hook — no no-resume
• Readonly-hook repro prints only caught: Error — no no-resume
• Backing storage unchanged when hook throws
• Language: property hook unset — exception from hook must abort unset and propagate (Zend/zend_property_hooks.c) #9666 unset-hook fix shares root unwinding if applicable

Verification

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