AOT: array property with a literal default reads as empty — count() returns 0, $this->c[1] returns 0

[PurHur]

Summary

A typed array property declared with a literal default is empty whenever it is read under AOT.
Silent wrong output — exit 0, plausible values.

VM is unaffected (6/6).

Reproducers

<?php
class C { private array $c = [1,2]; public function m(): int { return count($this->c); } }
echo (new C)->m(), "\n";

zend: 2
aot : 0

<?php
class C { private array $c = [7,8]; public function m(): int { return $this->c[1]; } }
echo (new C)->m(), "\n";

zend: 8
aot : 0

It is the property, not count() and not visibility

case	AOT
count($this->c) — private array prop	0
count($this->c) — public array prop	0
$x = $this->c; count($x) — via a local	0
$this->c[1] — element read, no count()	0
count($o->c) — read from outside the class	0
count($a) — plain local array, no class	ok, 2

So count() is fine on a local; visibility is irrelevant; copying to a local first does not help;
and element access fails the same way. The array property simply does not carry its declared
default into the object.

Deterministic — 0/3 runs matched under --repeat 3 on every failing case.

Why it matters

private array $items = []; with later population is one of the most common shapes in
object-oriented PHP. Anything reading such a property before reassignment sees an empty array and
computes wrong answers silently.

Context

Found while re-validating #23059 (task: "re-validate #23059 broadly"). A class with properties
followed by a method dense with locals produced pqx10 instead of pqx12 — the trailing
count($this->c) term was 0.

Environment: php-compiler:22.04-dev, PHP 8.2.32, LLVM 9, php bin/compile.php -o <bin> <file>,
master 11092acbb. Reproducers in build/micro/cnt/.

[PurHur]

claim: lane-C implementer — starting this run (AOT array property literal defaults empty)

[PurHur]

Merged via #24092

Fix: Object_::definePropertyDefault no longer forces every TYPE_ARRAY default to emptyArray; non-empty literals rebuild from the folded VM table at each new.

Verification:

php bin/compile.php -o /tmp/c.bin test/repro/issue_24086_aot_array_property_default.php && /tmp/c.bin
# → 2 (was 0)
vendor/bin/phpunit --filter 'array_property_literal_default|property_default_array_class_const'
# OK (5 tests)