Regression: unset($obj->arr[$k]) no-ops again on instance/static array props — Zend removes (re-#24250, zend_execute.c) #31818

Category

Regression: · php-src-strict · language (UNSET_DIM on object / static properties)

Problem

unset($obj->prop[$key]) / unset($this->prop[$key]) / unset(Class::$prop[$key]) must remove the array key on instance and static object properties (typed and untyped). After #24250 / #24263 this was green; on master 2026-08-17 it is a no-op again (likely regressed by recent typed-property dim work around #31770–#31784).

Userland ArrayAccess::offsetUnset that does unset($this->storage[$offset]) on a private/typed array property is broken the same way — isset($obj[$k]) stays true after unset($obj[$k]) even though offsetUnset runs.

Local $a[$k] unset still matches Zend (control).

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

UnsetComplianceTest / unset_object_array_dim.phpt fails: expected t=0 pt=0 u=0 pu=0 / aa=00, actual t=2 pt=1 u=2 pu=1 / aa=11.

php-src reference

• php/php-src Zend/zend_execute.c — ZEND_UNSET_DIM / property fetch + dim unset must mutate live array storage
• php/php-src Zend/zend_object_handlers.c — property ptr for unset
• Prior fix: Regression: unset($obj->arr[$k]) no-ops on typed/private instance array props — Zend removes (Zend/zend_execute.c) #24250 / Language: persist unset($obj->arr[$k]) into instance properties (#24250) #24263 (R-mode alias for following TYPE_UNSET)

PHP implementation target

• lib/VM.php / unset-dim lowering — property dim unset must write back (same class of fix as Language: persist unset($obj->arr[$k]) into instance properties (#24250) #24263); do not regress Language: dim-assign/append on uninitialized typed array property Errors — Zend auto-inits [] (zend_object_handlers.c) #31770 array auto-init on assign
• lib/Compiler.php / lib/JIT/ if UNSET_DIM is lowered separately
• php-in-PHP — no new C runtime branch

Repro

./script/docker-exec.sh -- bash -lc 'php test/repro/maintainer_gap_unset_object_array_dim.php'
./script/docker-exec.sh -- bash -lc 'php bin/vm.php test/repro/maintainer_gap_unset_object_array_dim.php'
./script/docker-exec.sh -- bash -lc 'php bin/vm.php test/repro/maintainer_gap_unset_object_array_dim_static.php'
./script/phpunit.sh --filter UnsetComplianceTest

Done when

• Instance + static unset($obj->arr[$k]) removes the key (typed/untyped, public/private) matching Zend
• ArrayAccess unset($obj[$k]) that unsets a property dim leaves isset false
• UnsetComplianceTest / unset_object_array_dim.phpt green
• Local unset($a[$k]) and Language: dim-assign/append on uninitialized typed array property Errors — Zend auto-inits [] (zend_object_handlers.c) #31770 dim-assign auto-init for typed array still green
• php-src-strict; no php-compiler-strict shortcut