Stdlib: array_reduce() — enum case + int arithmetic must TypeError not coerce backing int (ext/standard/array.c)

[PurHur]

Category

stdlib | php-src-strict

Problem

array_reduce() with an int-backed enum case array and a callback that adds integers must TypeError when Zend cannot coerce enum objects to int in the reducer. This compiler coerces enum cases to backing ints and returns a sum.

Distinct from #5626 (callback must receive enum objects); this issue is the TypeError when reducer performs illegal scalar arithmetic on enum cases.

php-src reference

• php/php-src ext/standard/array.c — PHP_FUNCTION(array_reduce)
• php/php-src Zend/zend_operators.c — add_function on enum zvals → TypeError

Repro

<?php
enum E: int { case A = 1; case B = 2; }
try {
    echo array_reduce([E::A, E::B], fn($c, $i) => $c + $i, 0), "\n";
} catch (TypeError $e) {
    echo "te\n";
}

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php repro.php          # te
php bin/vm.php repro.php   # 3 today
'

Runtime	Output
Zend PHP 8.2+	te (TypeError on enum + int)
VM	3

Scope

Module	Path
VM	ext/standard/array_reduce.php, enum-aware reducer in lib/VM/
JIT	defer or mirror VM strictness
Tests	test/compliance/cases/stdlib/array_reduce_enum_type_error.phpt

Done when

• Repro prints te on VM under php-src-strict
• Valid reducers that preserve enum objects still tracked in Stdlib: array_reduce() on enum case arrays — closure callbacks must preserve enum objects (ext/standard/array.c) #5626
• ./script/ci-fast.sh --filter array_reduce_enum green

Related

• Stdlib: array_reduce() on enum case arrays — closure callbacks must preserve enum objects (ext/standard/array.c) #5626 preserve enum objects in callbacks
• Stdlib: array_sum()/array_product() — int-backed enum cases must sum backing values not 0 (ext/standard/array.c) #8828 array_sum/array_product enum semantics

[PurHur]

Compliance guard added in #16475 () — behavior green on master.