Stdlib: class_implements() on enum must return UnitEnum/BackedEnum (ext/standard/basic_functions.c)

[PurHur]

Category

stdlib

Problem

class_implements() on an enum must return the built-in interfaces UnitEnum and (for backed enums) BackedEnum, like Zend. This compiler returns an empty array.

php-src reference

• ext/standard/basic_functions.c — PHP_FUNCTION(class_implements)
• Zend/zend_enum.c — enum implements UnitEnum / BackedEnum

Repro

test/compliance/cases/stdlib/class_implements_enum_repro.php:

<?php
enum E: int { case A = 1; }
var_dump(class_implements(E::class));

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && cd /compiler && php bin/vm.php test/compliance/cases/stdlib/class_implements_enum_repro.php'

Runtime	Today
Zend	array(2) { ["UnitEnum"]=> string(8) "UnitEnum" ["BackedEnum"]=> string(10) "BackedEnum" }
VM	array(0) { }

Scope (this repo)

Area	Path
Builtin	ext/standard/class_implements.php / VmClassIntrospection
Enum metadata	lib/VM/EnumSupport.php or class registry — record implemented interfaces at compile time

Done when

• Repro var_dump matches Zend for unit and backed enums.
• class_implements(E::class, false) autoload flag behavior matches php-src (document if deferred).

Related

• Stdlib: ReflectionProperty — attributes + type + visibility parity (ext/reflection/php_reflection.c) #4384 — ReflectionClass implements parity

[PurHur]

claim: PHP Compiler STD Lib — starting this run

[PurHur]

Unclaiming: class_implements() on enum already green on master (#5651). VM repro returns UnitEnum+BackedEnum; compliance PHPT + ClassImplementsBuiltinTest pass. Closing as duplicate unless repro differs.

[PurHur]

Parity backlog audit (2026-06-18) — partial fix, case operand gap

Verified on VM today (./script/docker-exec.sh):

Operand	VM today	Zend
class_implements(E::class) backed enum	✅ UnitEnum, BackedEnum	same
class_implements(U::class) unit enum	✅ UnitEnum only	same
class_implements(E::A) enum case	❌ bool(false)	array with interfaces
class_implements(U::A) unit case	❌ bool(false)	UnitEnum

Update Done when: enum type (E::class) is green; remaining work is case object operands — filed as #9686 (implementation-ready). Close this issue when both type + case paths match Zend, or fold into #9686 and close here.

Repro (case operand — still failing)

<?php
enum E: int { case A = 1; }
var_dump(class_implements(E::A));

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php -r "enum E: int { case A = 1; } var_dump(class_implements(E::A));"'

[PurHur]

Closing as fixed on current master (2026-07-19 maintainer triage).

Verified (PHP_COMPILER_PROFILE=8.4):

enum E: int { case A = 1; }
var_export(class_implements(E::class));
// UnitEnum + BackedEnum present

Matches Zend. Re-open if a unit-enum-only or interface edge still diverges.