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Regression: prev() string-concat nested operand — returns false not element (re-#13811, ext/standard/array.c) #13903
Description
Category
stdlib · php-src-strict · regression (re-open of #13811)
Problem
#13811 was closed but prev() in string concatenation still fails on VM (2026-06-30). After next($array), prev($array) must return the previous element value (e.g. int 1). When used as a nested operand inside string concatenation with var_export(..., true), the VM returns false instead of the element.
Standalone prev($array) works; dot-concat form fails.
php-src reference
ext/standard/array.c—php_prev,zend_hash_move_backwards_ex
Repro (verified 2026-06-30)
test/repro/maintainer_gap_prev_concat_operand.php
php bin/vm.php test/repro/maintainer_gap_prev_concat_operand.php| Check | Zend | VM |
|---|---|---|
next($a); 'prev='.var_export(prev($a), true) |
prev=1 |
prev=false |
Standalone prev($a) |
1 |
1 |
Scope (PHP-in-PHP first)
| Layer | Path |
|---|---|
| VM | ext/standard/prev.php, ext/standard/VmArrayPointer.php |
| Compiler | nested-call / concat operand lowering |
| JIT | ext/standard/JitArrayPointer.php after VM green |
Done when (php-src-strict)
- Repro exits 0 on VM
-
prev()returns correct element in concat contexts - JIT/AOT agree when in scope
Verification
php bin/vm.php test/repro/maintainer_gap_prev_concat_operand.phpLinks
- Epic Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492 · re-Regression: prev() string-concat nested operand — returns true not element (ext/standard/array.c) #13811 · sibling Regression: next() string-concat nested operand — returns true not element (ext/standard/array.c) #13830 (
next()), Regression: Generator::current()/::key() string-concat nested operand — returns true not yielded value (Zend/zend_generators.c) #13899 (Generator)
Activity
PurHur commentedon Jun 30, 2026
claim released: worker-lane-b — scoped to compiler root cause #13916 first
PurHur commentedon Jun 30, 2026
claim: cursor-agent-lane-b — batch (issues #13903, #13912 via compiler #13916 family)
Add prev() concat operand repro and PHPUnit guard (#13903). (#13922)
PurHur commentedon Jun 30, 2026
Merged guard via #13922. Compiler root cause fixed on master (#13912 statementLevelFuncCallBeforeHoistedSiblingChain). Verification:
php bin/vm.php test/repro/maintainer_gap_prev_concat_operand.php→ ok;phpunit --filter testVarExportNestedPrevUsesFuncCallProducerSlotgreen.