Stdlib: is_subclass_of() on enum cases — UnitEnum/BackedEnum must be true (ext/standard/class.c)

[PurHur]

Category

stdlib

Summary

is_subclass_of() on enum case objects must recognize the built-in UnitEnum / BackedEnum interfaces, matching Zend. Today the VM returns false for both backed and unit cases vs interface names.

Related: #5422 (class_implements() parity) — same instanceof_interface path in php-src; fix may share lib/VM/ enum case + interface checks.

php-src reference

• php/php-src ext/standard/basic_functions.c — PHP_FUNCTION(is_subclass_of) → zend_is_a()
• php/php-src Zend/zend_API.c — enum case instanceof against UnitEnum / BackedEnum

Repro (today)

test/compliance/cases/stdlib/is_subclass_of_enum_case.phpt

<?php
enum E: int { case A = 1; }
enum U { case X; }
var_export(is_subclass_of(E::A, BackedEnum::class));
var_export(is_subclass_of(E::A, UnitEnum::class));
var_export(is_subclass_of(U::X, UnitEnum::class));
var_export(is_subclass_of(U::X, BackedEnum::class));

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

Call	Zend	VM today
is_subclass_of(E::A, BackedEnum::class)	true	false
is_subclass_of(E::A, UnitEnum::class)	true	false
is_subclass_of(U::X, UnitEnum::class)	true	false
is_subclass_of(U::X, BackedEnum::class)	false	false

Scope (PHP-in-PHP)

• ext/standard/is_subclass_of.php + VM builtin — enum case interface table
• Wire to same helpers as is_a() / instanceof (Stdlib: is_subclass_of() on enum cases — UnitEnum/BackedEnum must be true (ext/standard/class.c) #5642, Stdlib: class_implements() on enum case object — must return UnitEnum/BackedEnum (ext/standard/basic_functions.c) #5651)
• No new runtime/*.c logic

Done when

• Repro table matches Zend on VM
• is_subclass_of(E::A, 'BackedEnum') string form works (not only ::class)
• JIT/AOT: follow-up issue if MCJIT path still returns false
• PHPT green: is_subclass_of_enum_case.phpt

Verification

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && vendor/bin/phpunit --filter is_subclass_of_enum_case'

Links

• Stdlib: class_implements() on enum must return UnitEnum/BackedEnum (ext/standard/basic_functions.c) #5422 class_implements() on enum type · Stdlib: class_implements() on enum case object — must return UnitEnum/BackedEnum (ext/standard/basic_functions.c) #5651 on enum case object · Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492

[PurHur]

claim: agent-lane-c — starting this run

[PurHur]

Merged via #7507.

Fix: is_subclass_of() now accepts TYPE_ENUM_CASE operands and routes enum cases through VmReflection::isSubclassOfObject() — matches UnitEnum/BackedEnum via existing EnumCaseSupport::valueMatchesInstanceOfClassName() (same path as is_a() / #5651), returns false for the declaring enum class.

Verification (green):

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php test/repro/is_subclass_of_enum_case.php'
# truetruetruefalsefalse

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && vendor/bin/phpunit --filter is_subclass_of'
# OK (5 tests, 5 assertions)

JIT/AOT enum-case is_subclass_of left for follow-up per issue checklist.