Language: asymmetric visibility on constructor-promoted properties (zend_compile.c parity)

[PurHur]

Category

language

Problem

PHP 8.4 asymmetric visibility (public private(set)) on constructor-promoted properties must compile and enforce the same rules as ordinary properties. This compiler lowers asymmetric visibility via AsymmetricVisibilityRewriter / propertySetVisibility for explicit properties, but promoted parameters with private(set) may lose set-visibility metadata or allow illegal writes from the constructor body/global scope.

php-src reference

• Zend/zend_compile.c — promoted property visibility + asymmetric set visibility
• Zend/zend_object_handlers.c — asymmetric write checks

Repro (today)

<?php
class User {
    public function __construct(
        public private(set) string $name,
    ) {}
}
$u = new User('alice');
echo $u->name, "\n";
try {
    $u->name = 'bob';
} catch (Error $e) {
    echo $e->getMessage(), "\n";
}

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

Runtime	Expected (Zend)	Actual today
Zend	alice + cannot modify private(set) message	—
VM/JIT	same	may allow external write or wrong compile error

Scope (this repo)

Layer	Path
Compiler	lib/Compiler.php promoted param → property (asymmetricSetVisibilityFromCfgOp)
Rewriter	lib/SourcePreprocessor/AsymmetricVisibilityRewriter.php
VM / JIT	lib/VM.php, lib/JIT/AsymmetricVisibilityGuard.php
Tests	test/compliance/cases/language/asymmetric_visibility_promoted.phpt

Done when

• Repro matches Zend on VM and JIT (catchable Error on external write)
• Writes from inside class / constructor still allowed
• ./script/ci-fast.sh --filter asymmetric_visibility_promoted green

Links

• Base asymmetric: Language: PHP 8.4 asymmetric property visibility (public/private(set), etc.) #3165, JIT: Language: PHP 8.4 asymmetric visibility private(set) — JIT enforce + catchable Error (phase 2 of #3165) #4029, Language: asymmetric property visibility — JIT/AOT write guards (phase 2 of #3165, zend_compile.c) #4639

[PurHur]

claim: runforge-worker-lane-b — starting this run

[PurHur]

Merged via #4817.

Verification: vendor/bin/phpunit --filter asymmetric_visibility_promoted (VM + JIT compliance) and issue repro on bin/vm.php / bin/jit.php — external write throws catchable Error with Zend message; in-class rename() writes allowed.

Fix: PHPCfg Parser overlay sets promotionSetVisibility / Property::setVisibility from phpc-asymmetric-set:* markers so constructor-promoted private(set) metadata is preserved before compiler lowering.