Stdlib: is_callable() on enum case first-class callable returns false — invoke succeeds (Zend/zend_callable.c)

[PurHur]

Category

language · stdlib · php-src-strict

Problem

Enum case instance method first-class callables (E::Case->method(...)) compile and invoke correctly, but is_callable() returns false while Zend returns true. This breaks guards that gate invocation on is_callable() before calling.

Related compile work: #9398 (FCC parse). This issue is the runtime is_callable() probe once FCC exists.

php-src reference

• php/php-src Zend/zend_callable.c — zend_is_callable_at_frame, first-class callable / enum case method handling
• php/php-src Zend/zend_enum.c — enum case method binding

Repro

<?php
enum E: int {
    case A = 1;
    public function m(): string { return 'ok'; }
}

var_export(is_callable([E::A, 'm']));
echo "\n";
var_export(is_callable(E::A->m(...)));
echo "\n";
$c = E::A->m(...);
var_export($c());
echo "\n";

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php test/repro/enum_case_fcc_is_callable.php; php bin/vm.php test/repro/enum_case_fcc_is_callable.php'

Probe	Zend PHP 8.2+	VM today
is_callable([E::A, 'm'])	true	true
is_callable(E::A->m(...))	true	false
(E::A->m(...))()	'ok'	'ok'

Scope (PHP-in-PHP)

Layer	Path
VM	ext/standard/is_callable.php / callable classification helpers
Shared	Treat bound enum-case FCC like other Closure/FirstClassCallable objects
Tests	test/compliance/cases/language/enum_case_fcc_is_callable.phpt

Done when (php-src-strict)

• Repro: is_callable(E::A->m(...)) is true on VM
• (E::A->m(...))() still returns 'ok'
• JIT/AOT agree when FCC lowering is in scope

Related

• Language: enum case instance method first-class callable (... ) — compile fails PHPTypes (Zend/zend_compile.c) #9398 · Regression: enum case instance method dispatch — E::Case->method() fatals (re-#9658, Zend/zend_enum.c) #9726 · Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492

[PurHur]

claim: cursor-agent-lane-c — starting this run (language/FCC is_callable on enum case method; not ext/standard scope despite stdlib label)

[PurHur]

claim released: cursor-agent-lane-c — repro already green on master (VM + JIT): is_callable([E::A, 'm']) and is_callable(E::A->m(...)) both true; invoke returns 'ok'. Compliance enum_case_method_first_class_callable.phpt covers FCC invoke path.

[PurHur]

claim: cursor-agent-lane-c — starting this run (lane C empty; language-primary is_callable enum FCC parity, Zend/zend_callable.c)

[PurHur]

claim released: verified fixed on master — test/repro/enum_case_fcc_is_callable.php matches Zend (true/true/'ok'). No code change needed.

[PurHur]

Closed by lane-C audit (2026-06-23): inline repro green on master — is_callable(E::A->m(...)) returns true on VM matching Zend; invoke returns 'ok'.