Language: instance typed property enum case default must compile (extends #9747, re-#9715, Zend/zend_compile.c) #9954

Category

language · php-src-strict

Problem

Zend allows enum cases as default values for instance typed properties:

class P {
    public E $e = E::A;
}

Closed #9715 tracked parameter + property defaults; #9747 covers static typed properties only. Instance property defaults still fail at compile:

Cannot use int as default value for property $e of type E

because enum cases are lowered to backing scalars during default materialization.

php-src reference

• php/php-src Zend/zend_compile.c — property default validation for enum type hints
• php/php-src Zend/zend_enum.c — enum case zval as constant expression

Repro

<?php
declare(strict_types=1);

enum E: int { case A = 1; }

function f(E $e = E::A): void {
    echo $e->name, "\n";
}

class P {
    public E $e = E::A;
}

f();
$p = new P();
echo $p->e->name, "\n";

./script/docker-exec.sh php bin/vm.php test/repro-maintainer/enum_default_parameter_property.php
# Today: parseAndCompile failure on property default (parameter path may also fail — see #9730)
# Zend: prints A twice

Scope (this repo)

Done when (php-src-strict)

• Repro compiles; new P()->e is enum case E::A with ->name A
• Default parameter E $e = E::A compiles (coordinate Language: enum case typed parameter receives backing scalar — TypeError not enum object (Zend/zend_enum.c) #9730 runtime TypeError if separate)
• JIT/AOT property init uses enum case object, not backing scalar

Related

• Language: enum case as parameter/property default must compile (Zend/zend_compile.c) #9715 (closed) · Language: static typed property with enum case default must compile (extends #9715, Zend/zend_compile.c) #9747 static defaults · Language: enum case typed parameter receives backing scalar — TypeError not enum object (Zend/zend_enum.c) #9730 parameter runtime · Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492