Language: defined('Enum::CASE') — enum cases must be detectable (zend_constants.c) #4972

Category

language / stdlib — enum constant table + defined()

Problem

For backed/unit enums, Zend treats EnumName::CASE as a defined constant name for defined() and constant() (returns the enum case object). This compiler returns false from defined('E::A') even when E::A exists, and constant('E::A') throws Undefined constant.

Blocks reflection/bootstrap code that probes enum cases by name without hard-coding case objects.

php-src reference

• php/php-src Zend/zend_constants.c — enum case registration in constant table
• php/php-src ext/standard/basic_functions.c — PHP_FUNCTION(defined), PHP_FUNCTION(constant)
• php/php-src Zend/zend_enum.c — case hash / zend_enum_get_case_by_name()

Repro

<?php
enum E: int {
    case A = 1;
    case B = 2;
}
var_dump(defined('E::A'));
var_dump(defined('E::Z'));
var_dump(constant('E::A'));

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

Scope

Done when

• Repro matches Zend table above on VM
• constant('E::A') === E::A (see Stdlib: constant() — resolve user/class constant by name (ext/standard/basic_functions.c parity) #3484 — implement together or close duplicate)
• ./script/ci-fast.sh --filter defined_enum green

Related

• Stdlib: constant() — resolve user/class constant by name (ext/standard/basic_functions.c parity) #3484 / Stdlib: constant() — resolve constant by name including Class::CONST (ext/standard/basic_functions.c parity) #3577 — constant() class/enum lookup umbrella
• Stdlib: var_dump() — enum cases must display enum(Foo::Bar) not unknown() (Zend/zend.c hash API) #4739 — var_dump() enum case display
• Stdlib: get_debug_type() — enum cases must return enum class name (ext/standard/type.c parity) #4260 — get_debug_type() on enum cases