Stdlib: get_defined_vars() — exclude alias pollution + unset locals (zend_get_defined_vars parity) #4517

Category

stdlib

Status (expanded 2026-06-03 — implementation-ready)

Child of #4377. Implement this issue before closing the umbrella.

Problem

#4377 tracks general get_defined_vars() symbol-table parity. Concrete gaps in ext/standard/VmScope.php::getDefinedVars() today:

1. global $x; — Zend's snapshot may include globals linked into the function scope; this build iterates eachNamedScopeSlot() and can diverge on which names appear.
2. unset($local) — Zend excludes unset locals; this build skips only TYPE_NULL via callerVarIsSet() but can still expose slots that Zend omits.
3. $GLOBALS entries — must not duplicate superglobal table keys incorrectly.

php-src reference

• php/php-src ext/standard/basic_functions.c — zif_get_defined_vars → zend_get_defined_vars
• php/php-src Zend/zend_builtin_functions.c — zend_get_defined_vars(EXCLUDE)

Repro

repro_get_defined_vars.php:

<?php
function f() {
    global $g;
    $a = 1;
    $b = 2;
    unset($b);
    $vars = get_defined_vars();
    ksort($vars);
    var_export(array_keys($vars));
}
$g = 9;
f();

Commands

php repro_get_defined_vars.php
./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php repro_get_defined_vars.php'

Expected (Zend PHP 8.x — authoritative)

array (
  0 => 'a',
  1 => 'g',
)

Notes:

• b must not appear after unset($b).
• g appears because global $g imports the global into the function symbol table for this snapshot.
• Keys are sorted in repro for stable comparison; values are not required to match.

Failure signature today

vm.php often prints extra names (e.g. includes b, omits g, or lists $GLOBALS aliases). Capture actual output in PR and fix VmScope::getDefinedVars().

Scope (this repo)

• ext/standard/VmScope.php — getDefinedVars()
• ext/standard/get_defined_vars_.php
• lib/VM/Frame.php / scope slots — unset marking

Done when

• Repro array_keys output exactly matches Zend table above
• Stdlib: get_defined_vars() local symbol table parity #4377 umbrella repro (function locals + global $g) also green
• test/compliance/cases/stdlib/get_defined_vars_scope.phpt added
• ./script/ci-fast.sh --filter get_defined_vars green

Parent

• Stdlib: get_defined_vars() local symbol table parity #4377 — umbrella local symbol table parity (keep open until all repros green)

Labels

stdlib, implementation-ready