Language: bare self/parent typed properties reject valid assignments — Zend accepts (?self/unions OK) (zend_execute / TypeCheck)

[PurHur]

Category

Language: · php-src-strict · typed properties (self / parent)

Problem

Instance properties declared with a bare self or parent type must accept assignments that satisfy the early-bound class (same class / subclass for self; parent class / subclass for parent), including constructor-promoted public self $x. On master 2026-08-17, VM throws TypeError: Cannot assign A to property A::$x of type self (and the analogous parent error) even when assigning $this / a valid parent instance.

Control: ?self and self|string / parent|string already match Zend on this tree — only the bare self / parent forms are wrong. Param/return self types also match (not this bug).

Probed 2026-08-17 — host Zend PHP 8.2 vs php bin/vm.php.

Repro	Zend 8.2+	VM (2026-08-17)
$a->x = $a with public self $x	self_ok A	TypeError “… of type self”
$b->x = $b on subclass inheriting self	child_ok B	TypeError
$c->x = new P with public parent $x	parent_ok P	TypeError “… of type parent”
promoted public function __construct(public self $x)	promoted_ok	TypeError
public ?self $x assign $this	OK	OK (control)

php-src reference

• php/php-src Zend/zend_execute.c — typed property assign / ZEND_ASSIGN_OBJ
• php/php-src Zend/zend_object_handlers.c — property store type check
• php/php-src Zend/zend_types.h — self / parent type resolution for properties (early binding; static not allowed on properties)

PHP implementation target

• lib/VM/ type-check / TypeCheck / property assign — resolve bare self/parent property types to the declaring class (same path ?self already uses) before instanceof-style checks
• Constructor promotion uses the same property type metadata — fix once
• php-in-PHP — no new C runtime branch; sibling of trait self binding work (Language: trait self param/return types bind to trait name — Zend using class (Zend/zend_inheritance.c) #31744) but this is property types on ordinary classes

Repro

./script/docker-exec.sh -- bash -lc 'php test/repro/maintainer_gap_prop_type_self.php'
./script/docker-exec.sh -- bash -lc 'php bin/vm.php test/repro/maintainer_gap_prop_type_self.php'

Done when

• Bare self / parent property assigns match Zend (instance, inherited, promoted)
• ?self / union controls and wrong-type TypeErrors stay correct
• Compliance .phpt guard under test/compliance/cases/ for property self/parent
• php-src-strict; no php-compiler-strict shortcut

[PurHur]

claim: worker-lane-C — starting this run

[PurHur]

Merged via #31841

Verification

• ./script/docker-exec.sh -- bash -lc 'php bin/vm.php test/repro/maintainer_gap_prop_type_self.php' → self_ok / child_ok / parent_ok / nullable_ok / promoted_ok
• ./script/phpunit.sh --filter 'TypedPropSelfParent31835' → OK (2 tests, VM+JIT)

[PurHur]

claim: implementer-worker-lane-a — AOT regression: bare self/parent typed property assign stores wrong class (lane overflow)

[PurHur]

claim: compile-trust-lane-b — starting this run (lane overflow: north-star #32122/#31968 closed; spine missing lib/JIT/TypedPropertyClassAssignCheck.php after #35705)

[PurHur]

merged in #35708

verification:

• php script/check-selfhost-spine-coverage-sync.php → OK (8002 inventory files)
• ./script/phpunit.sh --filter 'TypedPropSelfParent31835' → OK (4 tests, 14 assertions)
• make north-star5-verify-fast → OK (fast)

[PurHur]

claim: implementer-worker-lane-a — starting this run (lane overflow: #36081 spurious undef warnings on assigned {main} CV TYPE_ASSIGN RHS — TypedPropSelfParent31835AotTest red)