Stdlib: usort()/uasort()/uksort() — enum case arrays must keep enum objects not backing scalars (ext/standard/array.c)

[PurHur]

Category

stdlib — php-src-strict

Problem

Sorting functions that reorder array elements in-place must preserve enum case objects when the array holds enum cases. sort() is tracked in #5691; usort(), uasort(), and uksort() are not and today replace elements with backing scalars after the user callback returns.

php-src reference

• php/php-src ext/standard/array.c — php_usort(), php_uasort(), php_uksort() (zval copy without enum unwrap)

Repro

<?php
enum E: int { case A = 1; case B = 2; }
$a = [E::B, E::A];
usort($a, fn($x, $y) => $x <=> $y);
var_export($a);
// Zend: [E::A, E::B]
// VM today: [1, 2]

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php -r "enum E: int { case A = 1; case B = 2; } \$a=[E::B,E::A]; usort(\$a, fn(\$x,\$y)=>\$x<=>\$y); var_export(\$a);"'

Repeat for uasort() (preserve keys) and uksort() (keys are enum cases in #8779 family).

Scope (this repo)

Piece	Path
VM sort helpers	ext/standard/VmArraySort.php or array builtin handlers for usort/uasort/uksort
Enum preservation	lib/VM/EnumCaseSupport.php — shared with #5691 / #5547
JIT	lib/JIT/Builtin/ArraySort.php (if lowered)

Done when

• Repro prints enum objects in sorted order on VM
• Callback receives enum case objects (see Stdlib: array_walk()/array_walk_recursive() must pass enum case objects to callbacks (ext/standard/array.c) #5567 for array_walk parity)
• test/compliance/cases/stdlib/usort_enum_case_preserve.phpt green
• uasort/uksort enum-key variants covered or filed as follow-ups

Verify

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && vendor/bin/phpunit --filter usort_enum'

Links

#1492 · #5691 · #5547 · #5585 · #8746

[PurHur]

claim: cursor-agent-lane-c — starting this run (enum preservation in usort/uasort; phase-2:language scope despite phase-4:stdlib label)

[PurHur]

Merged via #10457.

Root cause: php-cfg hoists enum case ClassConstFetch temps before inline fn() callbacks; the usort arg temp did not alias the ArrowFunction result, so enum prefetch slot $2 was sent as the callback instead of the Closure slot.

Fix: lib/Compiler.php — matchSingleClosureInlineProducer in callArgOperandIsClosureValue, closure slot override before enum prelude, compile-on-demand in slotForInlineClosureProducer.

Verification (green):
```bash
./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php bin/vm.php test/repro/maintainer_usort_enum_case.php
php bin/vm.php test/compliance/cases/stdlib/usort_enum_case_preserve.phpt
php bin/jit.php test/compliance/cases/stdlib/usort_enum_case_preserve_jit.phpt
vendor/bin/phpunit --filter UsortEnumCaseTest
'
```
VM/JIT output: array(0 => \\E::A, 1 => \\E::B) — enum objects preserved.