Stdlib: array_is_list() parity (ext/standard/type.c)

[PurHur]

Category

stdlib · php-src-strict

Problem

array_is_list() must match php-src zend_array_is_list() for key sequences and operand types. Audit (2026-06-18) confirms list-shape cases ([], [0,1], [1=>2], ['0'=>1], holes) already match Zend on VM. Remaining risk is operand typing and JIT lowering sharing the same VmArray::isList SSOT.

php-src reference

• ext/standard/type.c — PHP_FUNCTION(array_is_list) → zend_array_is_list()
• Zend/zend_hash.c — zend_array_is_list()
• Stubs: ext/standard/basic_functions.stub.php

Repro

<?php
declare(strict_types=1);

// List shape (all must match Zend)
var_dump(array_is_list([]));              // true
var_dump(array_is_list([0 => 1, 1 => 2])); // true
var_dump(array_is_list([1 => 2]));         // false
var_dump(array_is_list(['0' => 1]));       // true (string key "0" is int 0)
var_dump(array_is_list([0 => 1, 2 => 3])); // false (hole at index 1)

// Operand types — must TypeError, not silent coerce
try {
    array_is_list(null);
} catch (TypeError $e) {
    echo "null: ", $e->getMessage(), "\n";
}

enum Color: string { case Red = 'red'; }
try {
    array_is_list(Color::Red);
} catch (TypeError $e) {
    echo "enum: ", $e->getMessage(), "\n";
}

Commands

php repro.php                                    # Zend reference
./script/docker-exec.sh php bin/vm.php repro.php
./script/docker-exec.sh php bin/jit.php repro.php  # if JitArrayIsList wired

Zend expected (operand errors):

• array_is_list(): Argument #1 ($array) must be of type array, null given
• array_is_list(): Argument #1 ($array) must be of type array, Color given

Scope (this repo)

• ext/standard/array_is_list.php
• ext/standard/VmArray.php — VmArray::isList() (SSOT)
• lib/JIT/Builtin/JitArrayIsList.php (or equivalent) — must call same logic, not duplicate list walk in LLVM

Done when (php-src-strict)

• VM repro output matches Zend for all list-shape and TypeError cases above.
• JIT/AOT (if applicable) uses PHP SSOT via helper bridge — no second list-walk implementation.
• Add test/compliance/cases/array_is_list_*.phpt or unit beside repro covering hole + null + enum operands.
• Close only when VM and JIT paths green (or JIT explicitly documented VM-only with gap in docs/capabilities.md).

Notes

• Do not treat ['0'=>1] as false — php-src treats key 0 as list-eligible (verified against Zend 8.2+).

[PurHur]

Expanded spec — operand typing verified 2026-06-18

List-shape cases already match Zend on VM. Enum operand TypeError message is wrong — VM coerces enum to backing string before the type guard:

php bin/vm.php -r 'enum Color: string { case Red = "red"; } try { array_is_list(Color::Red); } catch (Throwable $e) { echo get_class($e), ": ", $e->getMessage(), "\n"; }'

Engine	Exception message
Zend	array_is_list(): Argument #1 ($array) must be of type array, Color given
VM	TypeError: ... must be of type array, string given

Fix: reject TYPE_ENUM_CASE (and other non-array zvals) before VmString/scalar coercion — reuse TypeCheck / VmArray::requireArrayArg pattern used by count() enum guards (#5892 family).

Operand repro block (add to compliance PHPT)

<?php
enum Color: string { case Red = 'red'; }

foreach ([null, Color::Red, 123, 'not-array'] as $bad) {
    try {
        array_is_list($bad);
        echo "no throw for ", get_debug_type($bad), "\n";
    } catch (TypeError $e) {
        echo get_debug_type($bad), ': ', $e->getMessage(), "\n";
    }
}

Done when (additions)

• Enum operand error names enum type (Color given), not backing scalar
• null / object / string operands match Zend TypeError text
• JIT JitArrayIsList (if present) calls same VmArray::isList + arg guard — no duplicate LLVM list walk
• ./script/ci-fast.sh --filter array_is_list green

Claim hint: small VM-only fix in ext/standard/array_is_list.php + shared array-arg guard; JIT follow-up optional same PR if JitArrayIsList already wired.

[PurHur]

Spec refresh — implementation-ready audit 2026-06-19

Verified VM gap (operand typing)

List-shape cases already match Zend. Enum operand TypeError message is wrong:

./script/docker-exec.sh php bin/vm.php -r "
enum Color: string { case Red = 'red'; }
try { array_is_list(Color::Red); } catch (TypeError \$e) { echo \$e->getMessage(); }
"

Runtime	Message
Zend 8.2+	array_is_list(): Argument #1 ($array) must be of type array, Color given
VM today	... must be of type array, string given

Root cause: enum case is materialized to backing string before the type check — same enum-preservation cluster as #9925 / #9342. Fix must use get_debug_type() / enum object type name, not coerce-then-check.

Repro file

Add/mirror: test/repro-maintainer/parity_array_is_list_enum_operand.php

Updated done-when

• Enum operand TypeError names the enum type (Color given), not backing scalar
• null operand message unchanged (already correct)
• JIT JitArrayIsList uses same VmArray::isList + shared TypeCheck guard — no LLVM duplicate list walk
• Compliance PHPT covers enum + null operands

php-src reference (operand path)

• ext/standard/type.c — Z_PARAM_ARRAY / zend_parse_parameters
• Zend/zend_enum.c — enum is IS_OBJECT at API boundary

[PurHur]

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

[PurHur]

claim released: repro green on master — enum operand TypeError names Color given. Pivoting.

[PurHur]

claim: worker-lane-a — starting this run (4737 green on master; pivoting here)

[PurHur]

claim released: repro green on master — enum operand TypeError names Color given on VM/JIT. Pivoting to #4743.

[PurHur]

Merged via #17858.

Finding: Operand typing parity was already green on master — VmArray::requireArray() / JitArrayKey::requireArrayArg() reject enum cases before backing-scalar coercion with Zend-matching `Color given` message.

Shipped: VM/JIT compliance PHPTs + `test/repro-maintainer/parity_array_is_list_enum_operand.php` guarding null + enum operand TypeError text.

Verification:
```bash
./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php test/repro-maintainer/parity_array_is_list_enum_operand.php
php bin/vm.php test/repro-maintainer/parity_array_is_list_enum_operand.php
php bin/jit.php test/repro-maintainer/parity_array_is_list_enum_operand.php
vendor/bin/phpunit test/compliance/ArrayIsListVMTest.php --filter array_is_list_enum_operand
vendor/bin/phpunit test/compliance/ArrayIsListJITTest.php --filter array_is_list_enum_operand
'
```
All green (VM + JIT compliance 1/1 each).