Language: asymmetric visibility on constructor-promoted properties — parse fails (PHP 8.4, Zend/zend_compile.c)

Problem

PHP 8.4 allows asymmetric visibility on promoted constructor parameters:

class C {
    public function __construct(public private(set) int $x = 1) {}
}
$c = new C(2);
echo $c->x; // Zend: 2

This compiler fails at parse/compile (Syntax error, unexpected T_ECHO / parser chokes on public private(set) in promotion position). Non-promoted asymmetric properties (public private(set) int $x) may parse elsewhere — this issue is promotion + asymmetric visibility only.

php-src reference

php/php-src Zend/zend_language_parser.y — promoted parameter modifiers
php/php-src Zend/zend_compile.c — ZEND_ACC_ASYMMETRIC_* on promoted properties
php/php-src Zend/zend_property_hooks.c — interaction with hooks (orthogonal)

Repro (failure today)

<?php
class C {
    public function __construct(public private(set) int $x = 1) {}
}
echo (new C(2))->x, "\n";

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php repro_asym_promoted.php      # PHP 8.4+: 2
php bin/vm.php repro_asym_promoted.php
'

Engine	Result
Zend PHP 8.4+	compiles; prints `2`; external `$c->x = 3` → Error (private set)
VM today	parse/compile failure

Scope (PHP-in-PHP first)

Path	Work
`lib/SourcePreprocessor/` or php-parser grammar hooks	accept asymmetric modifiers on promoted params
`lib/Compiler.php`	emit promoted property with asymmetric ACC flags
`lib/VM.php`	enforce get/set visibility masks on promoted props
Tests	`test/compliance/cases/language/asymmetric_promoted_ctor.phpt`

Reflection: #5060 / #6772 once properties compile.

Done when (php-src-strict)

Repro compiles and prints 2
Read via $c->x works; write from outside throws Zend-shaped Error
./script/ci-fast.sh --filter asymmetric_promoted_ctor green

Stdlib: ReflectionProperty::getAsymmetricVisibility() — set/get masks (ext/reflection/php_reflection.c) #5060 instance asymmetric reflection · Language: private(set) property hook write — wrong 'read-only' Error not private(set) message (Zend/zend_property_hooks.c) #9842 private(set) hook messages · Language: static property hooks — PHP 8.4 parse + get/set dispatch (Zend/zend_compile.c) #9725 static hooks · Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492

Spec refresh 2026-06-19 (parity architect): Repro now green on VM — public private(set) int $x in promoted ctor compiles, prints 2, and external write throws Error: Cannot modify private(set) property C::$x from global scope.

Recommend closing as fixed (or narrowing to any remaining edge not covered by test/compliance/cases/language/asymmetric_promoted_ctor.phpt if that test lands). Original parse failure no longer reproduces on master.

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

Add compliance guard for promoted public private(set) (#10001) (#10052)

Merged via #10052.

Status: Behavior was already fixed on master (AsymmetricVisibilityRewriter + AsymmetricVisibilityCompileCheck, refs #9724 / #6981). This PR adds the issue repro as a VM+JIT compliance guard.

Verification:

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php vendor/bin/phpunit --filter asymmetric_promoted_ctor
php bin/vm.php test/repro/asymmetric_visibility_promoted_ctor.php
'

OK (2 tests, 2 assertions)
alice
Cannot modify private(set) property User::$name from global scope

Wait I messed up the closing quote. Let me fix.

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Language: asymmetric visibility on constructor-promoted properties — parse fails (PHP 8.4, Zend/zend_compile.c) #10001

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Problem

php-src reference

Repro (failure today)

Scope (PHP-in-PHP first)

Done when (php-src-strict)

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Language: asymmetric visibility on constructor-promoted properties — parse fails (PHP 8.4, Zend/zend_compile.c) #10001

Description

Category

Problem

php-src reference

Repro (failure today)

Scope (PHP-in-PHP first)

Done when (php-src-strict)

Related

Activity

PurHur commented on Jun 19, 2026

PurHur commented on Jun 19, 2026

PurHur commented on Jun 19, 2026

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