Stdlib: min()/max() — enum case operands must return enum objects not backing scalars (#5570 regression)

[PurHur]

Category

stdlib · php-src-strict · regression

Problem

Zend min() / max() with backed enum case operands compares backing values and returns the winning enum case object. Closed #5570 / #5707 added VmMinMax::tryReduceEnumCasesTwoArg(), but VM still returns backing scalars (e.g. 1 instead of \E::A).

php-src reference

• php/php-src ext/standard/array.c — php_min, php_max, enum-aware zval comparison
• php/php-src Zend/zend_enum.c

Repro

<?php
enum E: int { case A = 1; case B = 2; }
var_export(min(E::A, E::B));
echo "\n";

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php -r "enum E: int { case A=1; case B=2; } var_export(min(E::A,E::B)); echo \"\\n\";"
php bin/vm.php -r "enum E: int { case A=1; case B=2; } var_export(min(E::A,E::B)); echo \"\\n\";"'

Engine	Output
Zend PHP 8.3+	\E::A
This compiler VM (today)	1

Also verify max(E::B, E::A) → \E::B, variadic min(E::A, E::B, …), and JIT/AOT when lowered.

Scope (this repo)

• ext/standard/VmMinMax.php — tryReduceEnumCasesTwoArg(), finishEnumCaseReduce() must materialize enum case return zvals
• lib/JIT/Builtin/*MinMax* — mirror enum return type
• test/compliance/cases/stdlib/min_max_enum_case.phpt

Done when

• Repro prints \E::A on VM (not 1)
• max() symmetric
• ./script/ci-fast.sh --filter min_max_enum green

Related

• Stdlib: max()/min() with enum case operands must return enum case objects (ext/standard/array.c) #5570, Stdlib: min()/max() enum case operands — regression vs closed #5570 (vmContext on Frame) #5707 (closed regressions), Stdlib: compact() — enum case variables must stay objects not backing scalars (ext/standard/basic_functions.c) #8686 (compact enum object parity), Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492

[PurHur]

claim: PHP Compiler STD Lib — starting this run

[PurHur]

Unclaiming: min()/max() enum case return already green on master — test/repro/issue_max_min_enum_cases.php and max_min_enum_cases.phpt match Zend. Recommend closing as duplicate unless repro differs.

[PurHur]

claim: PHP Compiler STD Lib — starting this run

[PurHur]

Unclaiming: min/max enum case behavior already green on master — repro + phpunit --filter max_min_enum pass. Residual var_export(min(...)) mismatch is #8724 scope.

[PurHur]

Verified green on master (2026-06-23, lane-C queue hygiene):

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php -r "enum E: int { case A=1; case B=2; } var_export(min(E::A,E::B)); echo \"\\n\";"
php bin/vm.php -r "enum E: int { case A=1; case B=2; } var_export(min(E::A,E::B)); echo \"\\n\";"'

Both engines print \\E::A. Closing stale open — fix landed via prior #5570/#5707 work.