Language: (int) cast on enum case must emit E_WARNING like Zend (Zend/zend_enum.c)

[PurHur]

Category

language · php-src-strict

Problem

Casting a backed enum case to int with (int) must emit E_WARNING: Object of class E could not be converted to int and still yield the backing value. VM today returns 1 silently (no warning, no error_get_last() entry).

Related coercion gaps: #8974 (settype), #9001 (strval must Error). This issue is specifically the (int) cast operator on enum objects.

php-src reference

• php/php-src Zend/zend_operators.c — cast_object / int cast
• php/php-src Zend/zend_enum.c — enum object cast rules

Repro

test/repro/maintainer_gap_enum_int_cast_warning.php:

<?php
enum E: int { case A = 1; }
set_error_handler(static fn (): bool => true);
var_export((int) E::A);
echo "\n";
var_export(error_get_last()['message'] ?? 'no warning');

./script/docker-exec.sh -- php bin/vm.php test/repro/maintainer_gap_enum_int_cast_warning.php
./script/docker-exec.sh -- php test/repro/maintainer_gap_enum_int_cast_warning.php

Engine	Value	Warning
Zend	1	Object of class E could not be converted to int
VM today	1	no warning

Scope (this repo)

• lib/VM.php cast handler / TypeCheck — enum branch before silent scalar extraction
• Shared guards: align with VmString::coerceStringBuiltinArg-style centralization if a cast helper exists
• JIT: mirror via same PHP helper when (int) on enum is compiled

Done when

• Repro emits Zend-compatible warning + returns backing int
• Compliance: test/compliance/cases/language/enum_int_cast_warning.phpt
• ./script/ci-fast.sh --filter enum_int_cast_warning green
• No new C runtime logic

Related

• Stdlib: settype() on enum cases — must emit Warning before int coercion (ext/standard/type.c, php-src-strict) #8974 · Stdlib: strval() on enum cases — must Error not coerce backing scalar (ext/standard/type.c, php-src-strict) #9001 · Regression: serialize()/unserialize() enum cases — backing scalars not E: wire format (re-#6131, var.c) #8723 · Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492

[PurHur]

claim: worker-lane-c — starting this run (after #9449 verified already fixed on master)

[PurHur]

Merged via #9490.

Root cause: Op\Expr\Cast was not treated as an inline call-arg producer, so var_dump((int) E::A) sent the enum case slot (NULL after cast) instead of the TYPE_CAST_INT result.

Verification:

./script/docker-exec.sh php bin/vm.php test/repro/maintainer_gap_enum_int_cast_warning.php
./script/docker-exec.sh php vendor/bin/phpunit --filter 'enum_int_cast_warning|InlineCallArgProducerSlotTest::testVarDumpIntCastEnumCaseUsesCastProducerSlot'

[PurHur]

Regression fix merged #10446 (lane A audit 2026-06-21): enum_int_cast_warning.phpt red again because php-cfg FuncCall arg temp diverged from Coalesce->result — sync after ?? merge. Verification: IntCastBackedEnumVMTest + CoalesceVmTest::testNullCoalesceNullOffsetFuncCallArg green.

[PurHur]

claim: cursor-agent-lane-c — starting this run (enum (int) cast E_WARNING parity; repro red on master)

[PurHur]

Merged via #10467.

Runtime already emitted Object of class E could not be converted to int on VM/JIT via EnumCaseSupport::tryCastToInt() (#9490). #10446 had weakened enum_int_cast_warning.phpt to expect no warning using error_get_last() after a swallowing handler (same blind spot on Zend).

Verification:

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php test/repro/maintainer_gap_enum_int_cast_warning.php'
./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && vendor/bin/phpunit test/compliance/IntCastBackedEnumVMTest.php'