Stdlib: pack() on backed enum operands — must warn and pack backing int, not VmJson::export fatal (ext/standard/pack.c)

[PurHur]

Category

stdlib

Problem

pack() forwards value operands through VmJson::export() in ext/standard/pack.php. Backed enum case arguments make the VM die with json_encode() value type not supported in this compiler build instead of matching Zend: E_WARNING (“Object of class E could not be converted to int”) and pack the backing scalar (pack('i', E::A) → 4-byte int 1).

Distinct from #4951 (hash() TypeError wording) and enum array coercion tickets.

php-src reference

• php/php-src ext/standard/pack.c — php_pack argument coercion

Repro

test/repro/parity_pack_backed_enum.php:

<?php
declare(strict_types=1);

enum E: int { case A = 1; }

try {
    $p = pack('i', E::A);
    echo 'len=', strlen($p), "\n";
} catch (Throwable $e) {
    echo get_class($e), ': ', $e->getMessage(), "\n";
}

docker info >/dev/null
./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php test/repro/parity_pack_backed_enum.php 2>&1 | head -5
php bin/vm.php test/repro/parity_pack_backed_enum.php 2>&1 | head -5'

Runtime	Expected
Zend	Warning + len=4 (32-bit int packing of 1)
VM today	Fatal / LogicException via VmJson::export

Scope (PHP-in-PHP)

Path	Work
ext/standard/pack.php	Coerce enum cases to backing via BackedEnum::backingValue before pack
lib/AOT/runtime/phpc_pack.c	JIT/AOT: same coercion; no enum branch in C long-term (#4675 machine formats)
Tests	test/compliance/cases/stdlib/pack_backed_enum.phpt

Done when

• pack('i', E::A) succeeds on VM with same byte length as Zend (little-endian host)
• Warning text matches Zend subset (contains “could not be converted” / enum class name)
• Unit enum / object operands still TypeError or warn per format — no VmJson::export fatal
• ./script/ci-fast.sh --filter pack_backed_enum green

Related

• Stdlib: pack()/unpack() — machine-endian integer formats (P/p/I/i/L/l/Q/q/J/j/V/v) and @ alignment (ext/standard/pack.c) #4675 (pack formats) · Stdlib: pack() on backed enum operands — must warn and pack backing int, not VmJson::export fatal (ext/standard/pack.c) #5713 · enum operand umbrella Stdlib: string builtins must TypeError on enum case operands (ext/standard/string.c) #5524

[PurHur]

claim: PHP Runtime → PHP — starting this run (#5713: pack('i'/'I') must be 4 bytes; backed enum operands E_WARNING + backing int).

[PurHur]

Merged via #7986.

Fix: pack('i'/'I') and matching unpack() now use sizeof(int)=4 (php-src ext/standard/pack.c) instead of PHP_INT_SIZE (8 on 64-bit). Backed enum operands already warn and pack backing int via EnumCaseSupport::packCoerceToLong; pack('i', E::A) now returns 4 bytes like Zend.

Verification:

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php test/repro/parity_pack_backed_enum.php   # len=4
php bin/vm.php test/repro/parity_pack_backed_enum.php   # len=4
vendor/bin/phpunit --filter pack_backed_enum   # OK (3 tests)
'

0 C runtime lines added.