Stdlib: array_map()/array_filter() on enum arrays must preserve enum case objects (ext/standard/array.c)

[PurHur]

Category

stdlib

Problem

array_map() and array_filter() must pass enum case objects through to callbacks and return arrays whose elements remain enum cases when the callback returns them unchanged. This compiler unwraps enum cases to backing scalars (int/string) during iteration, so identity callbacks produce numeric arrays.

php-src reference

• php/php-src ext/standard/array.c — PHP_FUNCTION(array_map), PHP_FUNCTION(array_filter)
• php/php-src Zend/zend_enum.c — enum case object zvals

Repro (verified 2026-06-04)

<?php
enum E: int { case A = 1; case B = 2; }

var_export(array_map(fn($x) => $x, [E::A, E::B]));
echo "\n";
var_export(array_filter([E::A, E::B], fn($x) => $x === E::A));
echo "\n";

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

Builtin	Zend	VM today
array_map(fn($x)=>$x, …)	array(0=>\E::A, 1=>\E::B)	array(0=>1, 1=>2)
array_filter(…, fn…)	array(0=>\E::A)	array(0=>1)

Scope (this repo)

Area	Path
VM	ext/standard/array_map.php, array_filter.php, VmArray.php / iterator helpers
JIT	lib/JIT/ArrayBuiltinHelper.php — enum-aware element copy
Tests	test/compliance/cases/stdlib/array_map_enum_identity.phpt, array_filter_enum.phpt

Distinct from #5547 (array_values/array_merge) and #5546 (sort family) — those are separate builtins with the same root scalarization bug.

Done when

• Repro A matches Zend on bin/vm.php
• Callbacks receive enum objects ($x === E::A strict works inside closure)
• JIT lowering matches VM for identity map/filter (or documented VM-only until phase 2)
• ./script/ci-fast.sh --filter array_map_enum green

Related

• Stdlib: array_filter() — third argument $mode (ARRAY_FILTER_USE_KEY / USE_BOTH) (ext/standard/array.c parity) #4243 array_filter third $mode argument
• Stdlib: array_map() — null zip + variadic source arrays (ext/standard/array.c php_array_map parity) #4539 array_map null zip
• Enum cluster: Stdlib: array_values()/array_merge() on enum case arrays coerces to backed scalars (ext/standard/array.c) #5547, Stdlib: string builtins must TypeError on enum case operands (ext/standard/string.c) #5524 string builtins on enum operands

[PurHur]

claim: PHP Compiler STD Lib — starting this run

[PurHur]

Unclaiming: array_map/array_filter enum identity already green on master. VM repro matches Zend (enum cases preserved). Recommend closing as duplicate unless repro differs.

[PurHur]

unclaim: stale — claim from 2026-06-09, no open PR, no activity >7d (maintainer triage 2026-06-16).

[PurHur]

claim: worker-lane-c — starting this run

[PurHur]

Merged via #18399.

Status: VM/JIT repro already matched Zend on master — enum cases stay objects through identity array_map() / strict-equality array_filter() callbacks.

Added: compliance guards array_map_enum_identity.phpt, array_filter_enum.phpt, plus test/repro/array_map_filter_enum_identity.php.

Verify:
```bash
./script/phpunit.sh --filter 'array_map_enum|array_filter_enum'
php bin/vm.php test/repro/array_map_filter_enum_identity.php
```