Stdlib: in_array() loose comparison must not match enum case to backing scalar (ext/standard/array.c)

[PurHur]

Category

stdlib

Problem

With loose comparison ($strict = false), in_array() must not treat a backed enum case as equal to its backing scalar (and vice versa). This compiler uses Variable::equals() which coerces enum cases to ints/strings, so in_array(1, [E::A], false) is true; Zend returns false.

php-src reference

• php/php-src ext/standard/array.c — php_in_array, zend_compare on IS_OBJECT enum cases
• php/php-src Zend/zend_enum.c — enum object identity in comparisons

Repro (verified 2026-06-04)

<?php
enum E: int { case A = 1; case B = 2; }
var_export(in_array(1, [E::A], false));
echo "\n";
var_export(in_array(E::A, [1], false));
echo "\n";
var_export(in_array('1', [E::A], false));
echo "\n";
var_export(in_array(E::A, [E::A], true)); // must stay true
echo "\n";

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php -r "enum E:int{case A=1;} var_export(in_array(1,[E::A],false)); echo \"\\n\";"
php bin/vm.php -r "enum E:int{case A=1;} var_export(in_array(1,[E::A],false)); echo \"\\n\";"
'

Expression	Zend	VM today
in_array(1, [E::A], false)	false	true
in_array(E::A, [1], false)	false	true
in_array(E::A, [E::A], true)	true	true

Scope (this repo)

Module	Path
VM	ext/standard/in_array.php — looseEquals() / equals() path
VM	lib/VM/Variable.php — enum-aware loose compare (coordinate #5178 loose ==)
JIT	ext/standard/in_array.php JIT lowering via ArrayBuiltinHelper
Tests	test/compliance/cases/stdlib/in_array_enum_loose.phpt

Done when

• Repro: first three lines false; strict identity line true
• ./script/ci-fast.sh --filter in_array_enum green

Related

• Language: loose == regression — int 0 matches non-numeric strings (Variable::looseIntegerFromString) #5178 loose == int/string · enum array coercion cluster (Stdlib: array_map()/array_filter() on enum arrays must preserve enum case objects (ext/standard/array.c) #5564–Stdlib: array_pop()/array_shift()/array_unshift()/array_splice() on enum case arrays coerces to backed scalars (ext/standard/array.c) #5586)