[PurHur]

Summary

• When preg_match() / preg_match_all() pattern compilation fails, Zend leaves the $matches out-parameter as an empty array [].
• VM wrappers were calling $target->null() on failure, so maintainer_gap_preg_match_duplicate_named.php failed even though compile rejection and preg_last_error() were already correct.

Root cause

ext/standard/preg_match.php and preg_match_all.php wrote null into the by-ref $matches slot on false return; php-src keeps the caller's empty array unchanged.

php-src reference

• ext/pcre/php_pcre.c — php_pcre_pcre2_compile() duplicate-name handling without PCRE2_DUPNAMES

PHP implementation

• ext/standard/preg_match.php, ext/standard/preg_match_all.php — write empty HashTable on compile failure

Verification

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php test/repro/maintainer_gap_preg_match_duplicate_named.php
php bin/vm.php test/repro/maintainer_gap_preg_match_duplicate_named.php
vendor/bin/phpunit --filter VmPregPatternTest
'

ok
repro:0
OK (9 tests, 18 assertions)

Closes #17584

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