Stdlib: unpack() $offset — enum case operand must TypeError not coerce backing int (ext/standard/pack.c)

[PurHur]

Category

stdlib — php-src-strict

Problem

unpack($format, $data, $offset) argument #3 must be int. Passing a backed enum case must TypeError (… must be of type int, E given). VM today coerces the backing scalar (e.g. E::A with backing 0 → offset 0) and proceeds.

php-src reference

• php/php-src ext/standard/pack.c — php_unpack() Z_PARAM_LONG on $offset

Repro

<?php
enum E: int { case A = 0; }
$data = "\x00\x00\x00\x01";
try {
    var_export(unpack('i', $data, E::A));
} catch (Throwable $e) {
    echo get_class($e) . ': ' . $e->getMessage() . "\n";
}

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php -r "enum E: int { case A = 0; } try { var_export(unpack(\"i\", \"\\x00\\x00\\x00\\x01\", E::A)); } catch (Throwable \$e) { echo get_class(\$e).\": \".\$e->getMessage(); }"'
# Today: array(1 => …) — WRONG (backing 0 used as offset)
# Target: TypeError: unpack(): Argument #3 ($offset) must be of type int, E given

Scope (this repo)

Piece	Path
VM builtin	ext/standard/unpack.php — $offset = VmMath::parseIntBuiltinArg(...)
Int guards	ext/standard/VmMath.php — rejectEnumCaseIntBuiltinArg() / enumCaseEntryForVariable()
Engine	ext/standard/UnpackEngine.php (unchanged once offset typed)
JIT	ext/standard/JitUnpack.php (mirror guard)

Root cause likely: enum case not detected before parseLongBuiltinArgCore() backing coercion.

Done when

• Repro throws TypeError on VM
• unpack('i', $data, 0) unchanged
• test/compliance/cases/stdlib/unpack_offset_enum_typeerror.phpt green
• JIT agrees when third arg is present

Verify

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

Links

#1492 · #6078 · #6213 · #6267 · #5780

[PurHur]

claim: cursor-agent-lane-b — starting this run

[PurHur]

claim released: repro green on master — VM and JIT both throw TypeError for unpack() offset enum case; unpack_enum_operand.phpt exists.

[PurHur]

claim: cursor-agent-lane-b — starting this run

[PurHur]

Merged via #18661.

Fix: unpack('i', pack(...), E::A) inline call-arg wiring — nested pack EXEC_RETURN feeds arg #2, hoisted enum feeds arg #3.

Verification:

php test/repro/maintainer_gap_unpack_enum_offset.php
php bin/vm.php test/repro/maintainer_gap_unpack_enum_offset.php
./script/phpunit.sh --filter 'unpack_enum_offset_typeerror|testUnpackInlinePackEnumOffsetCallArgSlots'

Both repro + PHPUnit green — TypeError on argument #3 ($offset) matches Zend.