Stdlib: json_encode() on unit enum cases — ValueError parity (ext/json/php_json.c)

[PurHur]

Category

stdlib

Problem

#4446 tracks backed enum json_encode → backing scalar. Unit enums (no backing type) are a separate Zend path: json_encode(E::A) must throw ValueError: json_encode(): Argument #1 (\$value) contains an invalid JSON type (PHP 8.3+).

This compiler returns a build-specific LogicException (json_encode() value type not supported in this compiler build) — wrong class/message and blocks parity tests.

php-src reference

• php/php-src ext/json/php_json.c — php_json_encode() enum branch
• php/php-src Zend/zend_enum.c — unit vs backed case

Repro

<?php
enum E { case A; }
try {
    json_encode(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 repro.php'
php repro.php

Engine	Output
Zend	ValueError: json_encode(): Argument #1 ($value) contains an invalid JSON type
This compiler VM	LogicException: json_encode() value type not supported…

Scope (this repo)

Layer	Path
VM	ext/standard/VmJson.php (or json module), enum case type dispatch
Bootstrap	pairs #4795 native VmJson (no host json_encode)
Tests	test/compliance/cases/stdlib/json_encode_unit_enum.phpt

Done when

• Repro throws ValueError with Zend message subset
• Backed enum still covered by Stdlib: serialize/json_encode/var_export on backed enum cases (ext/standard var + json parity) #4446 ("a" JSON string)
• ./script/ci-fast.sh --filter json_encode_unit_enum green

Related

• Stdlib: serialize/json_encode/var_export on backed enum cases (ext/standard var + json parity) #4446 · Bootstrap: VmJson json_encode/json_decode — native serialization without host json extension #4795 · Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492

[PurHur]

claim: PHP Compiler Ext — I/O & Crypto — starting this run (pivot from stale #10374/#17679/#11282)

[PurHur]

Merged via #17787

Fix: CompilerVersion::jsonEncodeUnitEnumValueError() gates Zend ValueError for unit enum json_encode() on PHP 8.3+ forward profile; reference profile still returns false (Zend 8.2 parity).

Verification:

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
export PHP_COMPILER_PROFILE=8.4
php bin/vm.php test/repro/maintainer_gap_json_encode_unit_enum.php
vendor/bin/phpunit --filter json_encode_unit_enum_value_error_forward_profile
vendor/bin/phpunit --filter json_encode_enum_case
'