Stdlib: class_alias() parity (Zend/zend_builtin_functions.c)

[PurHur]

Category

stdlib · php-src-strict

Problem

class_alias() must match php-src behavior for alias registration, return values, $autoload handling, and rejection of internal/Zend classes.

Today VM accepts class_alias('stdClass', 'Alias') and registers a working alias; Zend throws ValueError and leaves the alias unregistered.

php-src reference

• php/php-src ext/standard/basic_functions.c — PHP_FUNCTION(class_alias)
• php/php-src Zend/zend_builtin_functions.c — user-class-only alias targets

Repro

User class alias (happy path)

<?php
class A {}
var_dump(class_alias(A::class, 'B'));
var_dump(class_exists('B', false));
var_dump((new B) instanceof A);
var_dump(class_alias(A::class, 'C', false));

Internal class must fail

cat > /tmp/repro_class_alias_internal.php <<'PHP'
<?php
try {
    class_alias('stdClass', 'SC2');
    echo "alias ok\n";
} catch (Throwable $e) {
    echo get_class($e), ': ', $e->getMessage(), "\n";
}
var_dump(class_exists('SC2', false));
PHP
./script/docker-exec.sh -- bash -lc 'php /tmp/repro_class_alias_internal.php; php bin/vm.php /tmp/repro_class_alias_internal.php'

Probe	Zend	VM (today)
class_alias('stdClass', 'SC2')	ValueError (internal class)	succeeds
class_exists('SC2', false)	false	true

Commands

• Zend: php repro.php
• VM: ./script/docker-exec.sh php bin/vm.php repro.php

Scope (PHP-in-PHP)

Layer	Path
VM	ext/standard/class_alias.php
Registry	ext/standard/VmReflection.php / registerClassAlias — reject internal classes
JIT	JitClassAlias if behavior differs
Tests	test/compliance/cases/stdlib/class_alias_internal.phpt + user-class success case

Done when (php-src-strict)

• User-class repro matches Zend (return true, instanceof works, $autoload honored)
• Internal-class repro throws ValueError with Zend-shaped message; alias not registered
• Duplicate alias / invalid name errors match php-src
• Targeted compliance PHPT green in Docker

Related

• Stdlib: class_alias() parity (Zend/zend_builtin_functions.c) #9211 · Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492

[PurHur]

claim: cursor-agent-lane-B — batch (issues #9211)

[PurHur]

Merged via #13072.

Verification:

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php test/repro/maintainer_gap_class_alias_internal.php
php bin/vm.php test/repro/maintainer_gap_class_alias_internal.php
php vendor/bin/phpunit --filter class_alias_internal
'

Zend + VM: ValueError + false; PHPUnit OK (2 tests).