Stdlib: json_decode() — enum case json operand must TypeError (ext/json/php_json.c, php-src-strict)

[PurHur]

Summary

json_decode() must reject backed enum case operands with TypeError under php-src-strict. VM currently coerces enum cases to backing scalars and decodes JSON from the backing string.

php-src reference: ext/json/php_json.c — php_json_decode() validates $json as string before parsing; enum cases are objects, not strings.

PHP implementation target: ext/json/ VM builtin + VmString::coerceStringBuiltinArg / JitStringBuiltinArg guard on the json operand (no new C runtime).

Repro

test/repro/maintainer_json_decode_enum.php:

php bin/vm.php test/repro/maintainer_json_decode_enum.php
# VM today: int(1) from backing string '{"x":1}'
php test/repro/maintainer_json_decode_enum.php
# Zend: TypeError

Observed (2026-06-15):

• Zend: TypeError: json_decode(): Argument #1 ($json) must be of type string, E given
• VM: int(1) — decodes backing scalar

Done when (php-src-strict)

• json_decode() throws TypeError for enum case $json operand (VM; JIT/AOT if lowered)
• Compliance/repro guard in test/repro/ or test/compliance/
• Distinct from Stdlib: json_validate() — enum case operand must TypeError (ext/json/php_json.c, php-src-strict) #8748 (json_validate only)

Related

• Regression: backed enum case fetch materializes backing scalar not enum object (re-#8725, zend_enum.c) #8746, Stdlib: json_encode() on objects with property hooks — must invoke get hooks (ext/json/php_json.c) #8732
• North star: Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492

[PurHur]

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

[PurHur]

claim released: repro green on master — json_decode(E::A) throws TypeError; compliance json_decode_enum_typeerror.phpt + JIT variant pass VM+JIT.

[PurHur]

claim: PHP Compiler Ext — I/O & Crypto — starting this run

[PurHur]

Unclaiming — verified fixed on master (json_decode_enum_typeerror.phpt green VM+JIT). Switching to #6806.

[PurHur]

claim: PHP Compiler Ext — I/O & Crypto — starting this run

[PurHur]

Unclaiming — verified fixed on master: compliance tests green, VM throws TypeError for enum case operand without coercion. Closing candidate.

[PurHur]

Already fixed on master. VM correctly throws TypeError for enum case json operand:

$ php bin/vm.php -r 'enum E: string { case A = "{}" ; } try { json_decode(E::A); echo "uncaught\n"; } catch (TypeError $e) { echo "te\n"; }'
te

The shared VmString::coerceStringBuiltinArg() enum guard handles this.