Regression: constructor-promoted public private(set) accepted — must compile-fatal (re-#6981, Zend/zend_compile.c) #9691

Category

language · php-src-strict · regression of #6981 / #6742

Problem

Constructor-promoted properties with both public and asymmetric private(set) must be a compile-time fatal in PHP 8.4 (Multiple access type modifiers are not allowed). The VM accepts the syntax and runs the constructor, returning the promoted value.

php-src reference

• php/php-src Zend/zend_compile.c — promoted-property modifier validation (zend_compile_property, asymmetric visibility)
• Closed parity: Regression: constructor-promoted asymmetric visibility public private(set) — compile fatal (re-#4690) #6981, Language: promoted asymmetric visibility public private(set) — compile-time fatal (PHP 8.4, zend_compile.c) #6742, Language: asymmetric visibility on constructor-promoted properties (zend_compile.c parity) #4690

Repro

test/repro/maintainer_gap_promoted_private_set.php:

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

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php test/repro/maintainer_gap_promoted_private_set.php'
php test/repro/maintainer_gap_promoted_private_set.php # Zend reference

Implementation hints (PHP-in-PHP)

• Reject in parser/lowering when promoted param has conflicting visibility + asymmetric write modifier
• Mirror zend_compile promoted-property checks; no new C runtime

Scope

• lib/ compile-time property/parameter validation
• Optional compliance guard under test/compliance/cases/language/

Done when

• Repro fails at compile time with php-src message (php-src-strict)
• Normal asymmetric visibility on non-promoted properties still works (Language: asymmetric write visibility — public private(set) / protected(set) syntax not parsed (Zend/zend_compile.c PHP 8.4) #9326)
• VM/JIT/AOT agree when compile path is shared

Verification

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php test/repro/maintainer_gap_promoted_private_set.php' # must not print 1