Stdlib: preg_replace() array $pattern/$replacement overload — TypeError not AbA (ext/pcre/php_pcre.c)

[PurHur]

Summary

Zend supports preg_replace() with array $pattern and $replacement arguments (parallel pattern/replacement pairs). php-compiler VM rejects array $pattern with TypeError: Argument #1 ($pattern) must be of type string.

Distinct from #9363 (array subject replacement semantics).

php-src reference

• ext/pcre/php_pcre.c — php_pcre_replace_impl() array-pattern branch

Repro

<?php
declare(strict_types=1);

echo preg_replace(['/a/'], ['A'], 'aba'); // Zend: AbA — VM: TypeError

Committed repro: test/repro/maintainer_gap_preg_replace_array_pattern.php

./script/docker-exec.sh -- php test/repro/maintainer_gap_preg_replace_array_pattern.php      # PASS
./script/docker-exec.sh -- php bin/vm.php test/repro/maintainer_gap_preg_replace_array_pattern.php  # TypeError

Expected (php-src-strict)

• preg_replace(['/a/'], ['A'], 'aba') → 'AbA'
• Array pattern/replacement length mismatch → ValueError like Zend
• String subject unchanged; array-subject overload remains separate (Stdlib: preg_replace() array subject replaces wrong — doubles replacement on non-matching elements (ext/pcre/php_pcre.c) #9363)

Implementation hints (PHP-in-PHP)

• ext/standard / PCRE builtin in ext/ + VM lowering (lib/VM/Builtin/ or dedicated PCRE helper).
• Prefer PHP implementation shared by VM/JIT; shrink any C regex helpers rather than extending runtime/.

Done when

• Repro green on VM.
• Targeted test; JIT/AOT if those paths expose preg_replace.

[PurHur]

claim: cursor-agent-lane-c — starting this run (lane C queue is 100% stdlib/php-in-php; STD Lib automation lane — no competing claim in 48h)

[PurHur]

Merged via #10877

Fix: VM preg_replace() accepts array $pattern / $replacement — sequential multi-pattern replace in VmPreg (PHP-in-PHP, no C runtime).

Verification:

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php test/repro/maintainer_gap_preg_replace_array_pattern.php
php bin/vm.php test/repro/maintainer_gap_preg_replace_array_pattern.php
vendor/bin/phpunit test/unit/ext/PregReplaceArrayPatternTest.php
'

Zend + VM both print AbA / ABA; PHPUnit OK (3 tests).