Language: readonly class semantics — property write restrictions must match php-src (Zend/zend_compile.c)

[PurHur]

Category

language

Problem

Readonly classes (PHP 8.2) semantics are not implemented or diverge from php-src: readonly class C { ... } should implicitly make instance properties readonly and enforce write restrictions after initialization.

This is a language parity gap (not just reflection): user-visible writes must error like php-src.

Repro

<?php
readonly class C {
    public int $x;
    public function __construct(int $x) { $this->x = $x; }
}

$c = new C(1);
try {
    $c->x = 2;
    echo "NOERROR\n";
} catch (Throwable $e) {
    echo get_class($e), ": ", $e->getMessage(), "\n";
}

Expected (Zend/php-src)

• Throws Error on the write to $c->x (message matches php-src closely enough for compliance).

Actual (php-compiler)

• Write succeeds, wrong exception type, or message/behavior diverges.

php-src reference

• Zend/zend_compile.c (readonly class flagging, ZEND_ACC_READONLY_CLASS)
• Zend/zend_object_handlers.c (property write restrictions)
• ext/reflection/php_reflection.c (ties into ReflectionClass::isReadOnly() Stdlib: ReflectionClass::isReadOnly() — missing on readonly classes (ext/reflection/php_reflection.c) #5221)

Scope (this repo)

• Parser/compiler: readonly class flag propagation to runtime class metadata.
• VM property write path: enforce readonly class semantics and correct error type.

Done when

• Repro throws Error on second assignment under VM (php-src-strict).
• Add a minimal compliance test for readonly class write restriction.
• (Optional) Link/verify that Stdlib: ReflectionClass::isReadOnly() — missing on readonly classes (ext/reflection/php_reflection.c) #5221 becomes correct once semantics exist.

[PurHur]

claim: cursor-agent — starting this run

[PurHur]

Verified locally: readonly class property writes already throw Error with correct message.

Repro (from issue) under Docker:

• ./script/docker-exec.sh -- bash -lc "source script/php-env.sh && php <repro>.php" => Error: Cannot modify readonly property C::$x
• ./script/docker-exec.sh -- bash -lc "source script/php-env.sh && php bin/vm.php <repro>.php" => Error: Cannot modify readonly property C::$x

Existing compliance coverage: test/compliance/cases/language/readonly_class.phpt asserts Cannot modify readonly property Box::$v after construction.

Closing as already fixed on master.

[PurHur]

Closed: repro + existing compliance test indicate this is already implemented.